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I have recently started learning opengl on learnopengl.com. I am the chapter about textures. I have managed to load 2 textures however when I tell opengl to render the texture currently bound to GL_TEXTURE0 it instead draws the texture currently bound to GL_TEXTURE1.
My main.c file looks like this:
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include "glad/glad.h"
#include "GLFW/glfw3.h"
#include "stb/stb_image_init.h"
#define WIDTH 1080
#define HEIGHT 720
typedef unsigned int uint;
void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void process_input(GLFWwindow* window);
void check_shader_compilation(GLuint shader_object, GLenum shader_type);
void check_shader_linking(GLuint shader_program);
char* get_shader_code(const char* path);
int main(void) {
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "Triangle", NULL, NULL);
if (window == NULL) {
printf("Unable to create glfw window!\n");
return -1;
}
glfwMakeContextCurrent(window);
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
printf("Couldn't initialize glad!\n");
return -1;
}
glViewport(0, 0, WIDTH, HEIGHT);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
char* vertex_shader_code = get_shader_code("shaders/vertex.glsl");
GLuint vertex_shader_object = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertex_shader_object, 1, &vertex_shader_code, NULL);
glCompileShader(vertex_shader_object);
check_shader_compilation(vertex_shader_object, GL_VERTEX_SHADER);
free(vertex_shader_code);
char* fragment_shader_code = get_shader_code("shaders/fragment.glsl");
GLuint fragment_shader_object = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragment_shader_object, 1, &fragment_shader_code, NULL);
glCompileShader(fragment_shader_object);
check_shader_compilation(fragment_shader_object, GL_FRAGMENT_SHADER);
free(fragment_shader_code);
uint shader_program = glCreateProgram();
glAttachShader(shader_program, vertex_shader_object);
glAttachShader(shader_program, fragment_shader_object);
glLinkProgram(shader_program);
glUseProgram(shader_program);
check_shader_linking(shader_program);
float rectangle_data[] = {
// Coords Colors Texture coords
-0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, // Bottom Left
0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // Bottom Right
-0.5f, 0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, // Top Left
0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, // Top Right
};
unsigned int indicies[] = {
0, 2, 3,
0, 1, 3,
};
uint vao, vbo, ebo;
glGenVertexArrays(1, &vao);
glGenBuffers(1, &vbo);
glGenBuffers(1, &ebo);
glBindVertexArray(vao);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
glBufferData(GL_ARRAY_BUFFER, sizeof(rectangle_data), rectangle_data, GL_STATIC_DRAW);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indicies), indicies, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(float)*8, (void*)0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(float)*8, (void*)(sizeof(float)*3));
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(float)*8, (void*)(sizeof(float)*6));
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
glEnableVertexAttribArray(2);
float border_color[] = { 1.0f, 0.0f, 0.0f, 1.0f };
uint texture_buffer, texture2_buffer;
glGenBuffers(1, &texture_buffer);
glBindTexture(GL_TEXTURE_2D, texture_buffer);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, border_color);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
stbi_set_flip_vertically_on_load(true);
int width = 0, height = 0, n_channels = 0;
unsigned char* texture_image = stbi_load("assets/textures/luffy.jpg", &width, &height, &n_channels, 0);
if (texture_image) {
printf("Loaded texture0!\n");
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, texture_image);
glGenerateMipmap(GL_TEXTURE_2D);
}
else {
printf("Couldn't find the image for the texture\n");
exit(-1);
}
stbi_image_free(texture_image);
glGenBuffers(1, &texture2_buffer);
glBindTexture(GL_TEXTURE_2D, texture2_buffer);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, border_color);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
int t2_width = 0, t2_height = 0, t2_n_channels = 0;
unsigned char* texture2_image = stbi_load("assets/textures/face.png", &t2_width, &t2_height, &t2_n_channels, 0);
if (texture2_image) {
printf("Loaded texture1!\n");
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, t2_width, t2_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, texture2_image);
glGenerateMipmap(GL_TEXTURE_2D);
}
else {
printf("Couldn't find the image for texture2\n");
exit(-1);
}
stbi_image_free(texture2_image);
glUseProgram(shader_program);
glUniform1i(glGetUniformLocation(shader_program, "luffy"), 0);
glUniform1i(glGetUniformLocation(shader_program, "face"), 1);
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
while (!glfwWindowShouldClose(window)) {
process_input(window);
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture_buffer);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, texture2_buffer);
glBindVertexArray(vao);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
glfwPollEvents();
glfwSwapBuffers(window);
}
glDeleteVertexArrays(1, &vao);
glDeleteBuffers(1, &vbo);
glDeleteBuffers(1, &ebo);
glDeleteShader(vertex_shader_object);
glDeleteShader(fragment_shader_object);
glDeleteProgram(shader_program);
glfwTerminate();
return 0;
}
void framebuffer_size_callback(GLFWwindow* window, int width, int height) {
glViewport(0, 0, width, height);
}
void process_input(GLFWwindow* window) {
if (glfwGetKey(window, GLFW_KEY_Q) == true) {
glfwSetWindowShouldClose(window, true);
}
}
void check_shader_compilation(GLuint shader_object, GLenum shader_type) {
char* print_shader_type;
switch (shader_type) {
case GL_VERTEX_SHADER:
print_shader_type = "vertex";
break;
case GL_FRAGMENT_SHADER:
print_shader_type = "fragment";
break;
default:
printf("Cannot check for shader compilation, the shader_type is not GL_VERTEX_SHADER or GL_FRAGMENT_SHADER!\n");
exit(-1);
}
int shader_status;
glGetShaderiv(shader_object, GL_COMPILE_STATUS, &shader_status);
if (!shader_status) {
int message_length;
GLchar error[1024];
glGetShaderInfoLog(shader_object, 1024, &message_length, error);
printf("Could not compile the %s shader: \n %s\n", print_shader_type, error);
exit(-1);
}
else {
printf("Compiled the %s shader!\n", print_shader_type);
}
}
void check_shader_linking(GLuint shader_program) {
int linking_status;
glGetProgramiv(shader_program, GL_LINK_STATUS, &linking_status);
if (!linking_status) {
int message_length;
GLchar error[1024];
glGetProgramInfoLog(shader_program, 1024, &message_length, error);
printf("Could not link the shader program:\n %s\n", error);
exit(-1);
}
else {
printf("Linked the shader program!\n");
}
}
char* get_shader_code(const char* path) {
FILE* shader_file = fopen(path, "rb");
if (!shader_file) {
printf("Incorrect file path for shader: %s\n", path);
exit(-1);
}
fseek(shader_file, 0, SEEK_END);
int file_size = ftell(shader_file);
rewind(shader_file);
char* shader_code = malloc(file_size + 1);
shader_code[file_size] = '\0';
fread(shader_code, sizeof(char), file_size, shader_file);
return shader_code;
}
My Vertex shader is:
#version 330
layout (location = 0) in vec3 pos;
layout (location = 1) in vec3 colors;
layout (location = 2) in vec2 texCoords;
out vec3 vertex_colors;
out vec2 tex_coords;
void main() {
gl_Position = vec4(pos.x, pos.y, pos.z, 1.0);
vertex_colors = colors;
tex_coords = texCoords;
}
And my fragment shader is:
#version 330 core
out vec4 fragColor;
in vec3 vertex_colors;
in vec2 tex_coords;
uniform sampler2D luffy;
uniform sampler2D face;
void main() {
fragColor = texture(luffy, tex_coords);
}
Whenever I run the program, it texture it uses is the image in face.png, whereas I told it to use the image in luffy.jpg.
You never create any texture objects:
glGenBuffers(1, &texture_buffer);
glBindTexture(GL_TEXTURE_2D, texture_buffer);
glGenBuffers is for buffer objects, not for texture objects. You have to use glGenTextures. (Also calling your variable texture_buffer here is very confusing. There are buffer textures in the GL, but you're not using those here).
And since you use a core profile, the glBindTexture() call will just generate a GL error and have no other effect, becuase the object name you try to bind never was generated by glGenTextures. So in effect, you are working with texture object 0 here, and load both images to that texture object, with the latter overwriting the former. In a core profiler, using texture object 0 actually shouldn't work, but many drivers still allow it (as it was allowed in legacy GL), so that you actually see any texture at all is not guaranteed either.
I used matrices from cglm to modify the camera and what I should've seen on the screen is a small square, but nothing shows up. I have this code:
#define GLEW_STATIC
#define STB_IMAGE_IMPLEMENTATION
#include<stdio.h>
#include<stdlib.h>
#include<GL/glew.h>
#include<GLFW/glfw3.h>
#include<stdbool.h>
#include<string.h>
#include<stb/stb_image.h>
#include<cglm/cglm.h>
const unsigned int width = 1054;
const unsigned int height = 1057;
GLint uniColor;
GLint xploc;
GLint yploc;
void key_callback();
int main(){
if(!glfwInit()){
printf("Failed to initialize glfw!\n");
return 1;
}else{
printf("Successfully initialized glfw!\n");
}
//Set up GLFW
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow* window = glfwCreateWindow(width, height, "Title", NULL, NULL);
glfwSetKeyCallback(window, key_callback);
if(!window){
printf("Window creation failed!\n");
return 1;
}else{
printf("Window created successfully!\n");
}
glfwMakeContextCurrent(window);
//Initialize GLEW
glewExperimental = GL_TRUE;
if(glewInit() != GLEW_OK){
printf("Failed to initialize glew!\n");
return 1;
}else{
printf("Successfully initialized glew!\n");
}
//Set the swap interval to 1 millisecond
glfwSwapInterval(1);
//Set the vertices of the square
float Vertices[] = {
-0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f,
0.5f, 0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f,
0.5f, -0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 0.0f
};
//Set indices to make the square work
GLuint indices[] = {
0, 2, 1,
0, 3, 2
};
//Ignore this - it was the original square, but then I realized how I actually needed to make it work
float VerticesSquare[] = {
-0.5f, 0.5f, 0.0f,
0.5f, 0.5f, 0.0f,
0.5f, -0.5f, 0.0f,
-0.5f, -0.5f, 0.0f
};
printf("GLfloat variable called successfully\n");
//Create, compile and link the shaders to the shader program
GLuint ShaderProgram = glCreateProgram();
GLuint ShaderObjv = glCreateShader(GL_VERTEX_SHADER);
GLuint ShaderObjf = glCreateShader(GL_FRAGMENT_SHADER);
const GLchar* pvs[1];
const GLchar* pfs[1];
//Set the shader code
const char* pVertexShaderText = "#version 330 core\n"
"layout(location = 0) in vec3 Position;\n"
"layout(location = 1) in vec3 incolor;\n"
"layout(location = 2) in vec2 Tex;\n"
"out vec3 outcolor;\n"
"out vec2 texcoords;\n"
"uniform uint xp;\n"
"uniform uint yp;\n"
"uniform mat4 model;\n"
"uniform mat4 view;\n"
"uniform mat4 proj;\n"
"void main(){\n"
" gl_Position = proj * view * model * vec4(Position, 1.0f);\n"
"outcolor = incolor;\n"
"texcoords = Tex;\n"
"}";
const char* pFragmentShaderText = "#version 330 core\n"
"uniform vec3 color;\n"
"uniform sampler2D tex0;\n"
"in vec3 outcolor;\n"
"in vec2 texcoords;\n"
"out vec4 FragColor;\n"
"void main(){\n"
" FragColor = vec4(outcolor, 1.0f);\n"
"}";
pvs[0] = pVertexShaderText;
pfs[0] = pFragmentShaderText;
GLint LenghtsVertex[1];
GLint LenghtsFragment[1];
LenghtsVertex[0] = strlen(pVertexShaderText);
LenghtsFragment[0] = strlen(pFragmentShaderText);
glShaderSource(ShaderObjv, 1, pvs, LenghtsVertex);
glShaderSource(ShaderObjf, 1, pfs, LenghtsFragment);
glCompileShader(ShaderObjv);
glCompileShader(ShaderObjf);
//Shader error handling
GLint successvs;
glGetShaderiv(ShaderObjv, GL_COMPILE_STATUS, &successvs);
if(!successvs){
GLchar InfoLog1[1024];
glGetShaderInfoLog(ShaderObjv, sizeof(InfoLog1), NULL, InfoLog1);
fprintf(stderr, "Error compiling shader type %d: '%s'\n", GL_VERTEX_SHADER, InfoLog1);
return 1;
}
GLint successfs;
glGetShaderiv(ShaderObjf, GL_COMPILE_STATUS, &successfs);
if(!successfs){
GLchar InfoLog2[1024];
glGetShaderInfoLog(ShaderObjf, sizeof(InfoLog2), NULL, InfoLog2);
fprintf(stderr, "Error compiling shader type %d: '%s'\n", GL_FRAGMENT_SHADER, InfoLog2);
return 1;
}
glAttachShader(ShaderProgram, ShaderObjv);
glAttachShader(ShaderProgram, ShaderObjf);
glLinkProgram(ShaderProgram);
GLint success;
glGetProgramiv(ShaderProgram, GL_LINK_STATUS, &success);
if(!success){
GLchar InfoLog3[1024];
glGetProgramInfoLog(ShaderProgram, sizeof(InfoLog3), NULL, InfoLog3);
fprintf(stderr, "Error linking shader program: '%s'\n", InfoLog3);
return 1;
}
glValidateProgram(ShaderProgram);
GLint successl;
glGetProgramiv(ShaderProgram, GL_VALIDATE_STATUS, &successl);
if(!successl){
GLchar InfoLog4[1024];
glGetProgramInfoLog(ShaderProgram, sizeof(InfoLog4), NULL, InfoLog4);
fprintf(stderr, "Error validating shader program: '%s'\n", InfoLog4);
return 1;
}
glUseProgram(ShaderProgram);
//Set the vectors for the camera location
vec3 camerapos = {0.0f, 0.0f, -4.0f};
vec3 center = {0.0f, 0.0f, 0.0f};
vec3 yup = {0.0f, 1.0f, 0.0f};
//Create the matrices and make them be identity matrices
mat4 model;
mat4 view;
mat4 proj;
glm_mat4_identity(model);
glm_mat4_identity(view);
glm_mat4_identity(proj);
//Create the camera
glm_lookat(camerapos, center, yup, view);
glm_perspective(glm_rad(45.0f), (float)(width/height), 0.1f, 100.0f, proj);
//Set the uniform locations
GLint uniColor = glGetUniformLocation(ShaderProgram, "color");
GLint tex0uni = glGetUniformLocation(ShaderProgram, "tex0");
GLint xploc = glGetUniformLocation(ShaderProgram, "xp");
GLint yploc = glGetUniformLocation(ShaderProgram, "yp");
GLint modelloc = glGetUniformLocation(ShaderProgram, "model");
GLint viewloc = glGetUniformLocation(ShaderProgram, "view");
GLint projloc = glGetUniformLocation(ShaderProgram, "proj");
//Set the uniforms
glUniform3f(uniColor, 1.0f, 0.0f, 0.0f);
glUniform1i(tex0uni, 0);
glUniform1ui(xploc, 1);
glUniform1ui(yploc, 1);
glUniformMatrix4fv(modelloc, 1, GL_FALSE, (float*)model);
glUniformMatrix4fv(viewloc, 1, GL_FALSE, (float*)view);
glUniformMatrix4fv(projloc, 1, GL_FALSE, (float*)proj);
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
//Create the buffers
GLuint VBO;
GLuint VAO = 0;
GLuint EBO;
glGenBuffers(1, &VBO);
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &EBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBindVertexArray(VAO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
printf("Buffer created successfully\n");
glBufferData(GL_ARRAY_BUFFER, sizeof(Vertices), Vertices, GL_STATIC_DRAW);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
printf("Buffer data set up successfully\n");
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
glEnableVertexAttribArray(2);
printf("Enabling buffer successfull\n");
//Set the texture (I won't be using it for now)
int texwidth, texheight, texnum;
stbi_set_flip_vertically_on_load(true);
unsigned char* bytes = stbi_load("image.png", &texwidth, &texheight, &texnum, 0);
GLuint texture;
glGenTextures(1, &texture);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
float flatcolor[] = {1.0f, 1.0f, 1.0f, 1.0f};
glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, flatcolor);
printf("Set parameters successfully\n");
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, texwidth, texheight, 0, GL_RGB, GL_UNSIGNED_BYTE, bytes);
glGenerateMipmap(GL_TEXTURE_2D);
printf("Texture set successfully\n");
//Set the VertexAttribPointers at locations 0, 1 and 2
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
printf("First pointer succeeded\n");
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
printf("Second pointer succeeded\n");
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
printf("Third pointer succeeded\n");
printf("Setting up VectexAttribPointer successfull\n");
while(!glfwWindowShouldClose(window)){
glfwPollEvents();
glClear(GL_COLOR_BUFFER_BIT);
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
//glDrawArrays(GL_TRIANGLES, 0, 3);
//Draw the elements
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
GLenum err;
if((err = glGetError()) != GL_NO_ERROR){
printf("OpenGL error: %d\n", err);
}
glfwSwapBuffers(window);
}
return 0;
}
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
if(key == GLFW_KEY_R && action == GLFW_PRESS){
glUniform3f(uniColor, 1.0f, 0.0f, 0.0f);
}else if(key == GLFW_KEY_G && action == GLFW_PRESS){
glUniform3f(uniColor, 0.0f, 1.0f, 0.0f);
}else if(key == GLFW_KEY_B && action == GLFW_PRESS){
glUniform3f(uniColor, 0.0f, 0.0f, 1.0f);
}else if(key == GLFW_KEY_D && action == GLFW_PRESS){
glUniform1ui(xploc, 2);
}else if(key == GLFW_KEY_A && action == GLFW_PRESS){
glUniform1ui(xploc, 1);
}
}
I searched cglm's documentation, but didn't find a fix. There were some old stackoverflow questions on similar topics, but none actually solved my problem. I figured it has something to do with how I supply information to cglm's functions. I added comments, so it is easier to read.
As it turns out (float)(width/height) was supposed to be (float)width/(float)height as the first example was actually outputting 0 or 1, rather than 0.99716177861.
I am following the tutorials on learnopengl.com and I have come across an issues. I am writing my program in C rather than C++ and am using the linmath library for my matrix transformation and I have the files shader.c and texture.c. I believe that the issue is with my matrix transformation but I can't figure out where I've gone wrong. The program runs and it compiles, the window is created and the background colour is correct however the object does not show.
Here is the source:
#include <stdio.h>
#include <stdlib.h>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include "linmath.h"
#include "shader.h"
#include "texture.h"
void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow *window);
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
int main(){
// glfw: initialize and configure
// ------------------------------
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // uncomment this statement to fix compilation on OS X
// glfw window creation
// --------------------
GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
if (window == NULL){
printf("Failed to create GLFW window");
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
printf("Failed to initialize GLAD");
return -1;
}
Shader ourShader;
ourShader.ID = loadShader("3.3.shader.vs", "3.3.shader.fs");
// set up vertex data (and buffer(s)) and configure vertex attributes
// ------------------------------------------------------------------
float vertices[] = {
// positions // colors // texture coords
0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // top right
0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // bottom right
-0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, // bottom left
-0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f // top left
};
unsigned int indices[] = {
0, 1, 3, // first triangle
1, 2, 3 // second triangle
};
unsigned int VBO, VAO, EBO;
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
glGenBuffers(1, &EBO);
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
// position attribute
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
// color attribute
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
// texture coord attribute
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
glEnableVertexAttribArray(2);
Texture tex1 = loadTexture("container.jpg");
Texture tex2 = loadTexture("awesomeface.png");
// tell opengl for each sampler to which texture unit it belongs to (only has to be done once)
// -------------------------------------------------------------------------------------------
useShader(ourShader.ID);
setIntShader("texture1", 0, ourShader.ID);
setIntShader("texture2", 1, ourShader.ID);
// render loop
// -----------
while (!glfwWindowShouldClose(window))
{
// input
// -----
processInput(window);
// render
// ------
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
// bind textures on corresponding texture units
bindTexture(tex1, GL_TEXTURE0);
bindTexture(tex2, GL_TEXTURE1);
// activate shader
useShader(ourShader.ID);
// create transformations
mat4x4 model;
mat4x4 m;
mat4x4 view;
mat4x4 projection;
mat4x4_rotate(model, m, 1.0f, 0.0f, 0.0f, -0.95993f);
mat4x4_translate(view, 0.0f, 0.0f, -3.0f);
mat4x4_perspective(projection, 0.785f, (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
// pass them to the shaders
setMat4Shader("model", model, ourShader.ID);
setMat4Shader("view", view, ourShader.ID);
setMat4Shader("projection", projection, ourShader.ID);
// render container
glBindVertexArray(VAO);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
// glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
// -------------------------------------------------------------------------------
glfwSwapBuffers(window);
glfwPollEvents();
}
// optional: de-allocate all resources once they've outlived their purpose:
// ------------------------------------------------------------------------
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
glDeleteBuffers(1, &EBO);
// glfw: terminate, clearing all previously allocated GLFW resources.
// ------------------------------------------------------------------
glfwTerminate();
return 0;
}
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
glViewport(0, 0, width, height);
}
void processInput(GLFWwindow *window)
{
if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, GL_TRUE);
}
shader.c
#include "shader.h"
GLuint loadShader(const char * vertex_file_path,const char * fragment_file_path){
// Create the shaders
GLuint VertexShaderID = glCreateShader(GL_VERTEX_SHADER);
GLuint FragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);
// Read the Vertex Shader code from the file
char* VertexShaderCode;
FILE * vertexFile = fopen(vertex_file_path, "r");
if( vertexFile == NULL ){
printf("Impossible to open the file !\n");
return LOAD_FAILURE;
}
long vertex_file_size;
fseek(vertexFile, 0, SEEK_END);
vertex_file_size = ftell(vertexFile);
rewind(vertexFile);
VertexShaderCode = malloc((vertex_file_size + 1) * (sizeof(char)));
fread(VertexShaderCode, sizeof(char), vertex_file_size, vertexFile);
fclose(vertexFile);
VertexShaderCode[vertex_file_size] = 0;
// Read the Fragment Shader code from the file
char* FragmentShaderCode;
FILE * fragmentFile = fopen(fragment_file_path, "r");
if( fragmentFile == NULL ){
printf("Impossible to open the file !\n");
return LOAD_FAILURE;
}
long fragment_file_size;
fseek(fragmentFile, 0, SEEK_END);
fragment_file_size = ftell(fragmentFile);
rewind(fragmentFile);
FragmentShaderCode = malloc((fragment_file_size + 1) * (sizeof(char)));
fread(FragmentShaderCode, sizeof(char), fragment_file_size, fragmentFile);
fclose(fragmentFile);
FragmentShaderCode[fragment_file_size] = 0;
const char* vsCode = VertexShaderCode;
const char* fsCode = FragmentShaderCode;
// 2. compile shaders
unsigned int vertex, fragment;
int success;
char infoLog[512];
// vertex shader
vertex = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertex, 1, &vsCode, NULL);
glCompileShader(vertex);
checkCompileErrors(vertex, "VERTEX");
// fragment Shader
fragment = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragment, 1, &fsCode, NULL);
glCompileShader(fragment);
checkCompileErrors(fragment, "FRAGMENT");
// shader Program
GLuint ID = glCreateProgram();
glAttachShader(ID, vertex);
glAttachShader(ID, fragment);
glLinkProgram(ID);
checkCompileErrors(ID, "PROGRAM");
// delete the shaders as they're linked into our program now and no longer necessery
glDeleteShader(vertex);
glDeleteShader(fragment);
return ID;
}
void useShader(unsigned int ID){
glUseProgram(ID);
}
void setBoolShader(const char * name, int value, unsigned int ID)
{
glUniform1i(glGetUniformLocation(ID, name), value);
}
void setIntShader(const char * name, int value, unsigned int ID)
{
glUniform1i(glGetUniformLocation(ID, name), value);
}
void setFloatShader(const char * name, float value, unsigned int ID)
{
glUniform1f(glGetUniformLocation(ID, name), value);
}
void setMat4Shader(const char * name, mat4x4 mat, unsigned int ID)
{
glUniformMatrix4fv(glGetUniformLocation(ID, name), 1, GL_FALSE, *mat);
}
void checkCompileErrors(GLuint shader, char type[])
{
GLint success;
GLchar infoLog[1024];
if(strncmp(type, "PROGRAM", 7) != 0)
{
glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
if(!success)
{
glGetShaderInfoLog(shader, 1024, NULL, infoLog);
printf("ERROR::SHADER_COMPILATION_ERROR of type: %s \n %s \n", type, infoLog);
}
}
else
{
glGetProgramiv(shader, GL_LINK_STATUS, &success);
if(!success)
{
glGetProgramInfoLog(shader, 1024, NULL, infoLog);
printf("ERROR::SHADER_COMPILATION_ERROR of type: %s \n %s \n", type, infoLog);
}
}
}
texture.c
#include "texture.h"
Texture loadTexture(const char* path){
unsigned int texture;
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
// set the texture wrapping/filtering options (on the currently bound texture object)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
//load texture
int width, height, nrChannels;
unsigned char *data = SOIL_load_image(path, &width, &height, &nrChannels, SOIL_LOAD_RGB);
if(data){
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
} else{
printf("Failed to load Image");
}
SOIL_free_image_data(data);
Texture t;
t.ID = texture;
t.path = path;
return t;
}
void bindTexture(Texture texture, GLenum unit){
// bind textures on corresponding texture units
glActiveTexture(unit);
glBindTexture(GL_TEXTURE_2D, texture.ID);
}
vertex shader
#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec2 aTexCoord;
out vec2 TexCoord;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main()
{
gl_Position = projection * view * model * vec4(aPos, 1.0);
TexCoord = vec2(aTexCoord.x, aTexCoord.y);
}
Fragment Shader
#version 330 core
out vec4 FragColor;
in vec2 TexCoord;
// texture samplers
uniform sampler2D texture1;
uniform sampler2D texture2;
void main()
{
// linearly interpolate between both textures (80% container, 20% awesomeface)
FragColor = mix(texture(texture1, TexCoord), texture(texture2, TexCoord), 0.2);
}
It's second day I'm trying to draw a triangle using OpenGL 3.3 with shaders, but I can't get it to work. No error messages are printed out. I also stepped through every line with debugger and GL_GetError() stays 0 (no error) all the time except immediately after glewInit() call, but folks say it's OK. I have no idea what is wrong with the code or my computer. I use lubuntu 15.04 and glxinfo | grep "OpenGL" prints
OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) Bay Trail
OpenGL core profile version string: 3.3 (Core Profile) Mesa 10.5.9
OpenGL core profile shading language version string: 3.30
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:
OpenGL version string: 3.0 Mesa 10.5.9
OpenGL shading language version string: 1.30
OpenGL context flags: (none)
OpenGL extensions:
OpenGL ES profile version string: OpenGL ES 3.0 Mesa 10.5.9
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.00
OpenGL ES profile extensions:
This is my program, mere 100 LOC without any external dependencies:
#include <GL/glew.h>
#include <GL/freeglut.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
GLuint VBO;
GLuint prog;
const GLchar *vert_shader_src =
"#version 330\n"
"layout (location = 0) in vec3 Position;\n"
"void main() {\n"
"gl_Position = vec4(0.5*Position.x, 0.5*Position.y, Position.z, 1.0); }\n";
const GLchar *frag_shader_src =
"#version 330\n"
"out vec4 FragColor;\n"
"void main() {\n"
"FragColor = vec4(1.0, 0.0, 0.0, 1.0); }";
void render(void) {
glClear(GL_COLOR_BUFFER_BIT);
glUseProgram(prog);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
glDrawArrays(GL_TRIANGLES, 0, 3);
glDisableVertexAttribArray(0);
glutSwapBuffers(); }
void initGlut(int *argc_ptr, char **argv, void (*renderCallback)(void)) {
glutInit(argc_ptr, argv);
glutInitContextVersion(3, 3);
glutInitWindowSize(600, 600);
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE);
glutCreateWindow("minigl");
glutDisplayFunc(renderCallback); }
void initVBO(void) {
float pts[9] = {-1.0f, -1.0f, 0.0f, 1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f};
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(pts), pts, GL_STATIC_DRAW); }
int initProg(void) {
prog = glCreateProgram();
GLuint vshade = glCreateShader(GL_VERTEX_SHADER);
GLuint fshade = glCreateShader(GL_FRAGMENT_SHADER);
const GLchar **v_src = &vert_shader_src;
const GLchar **f_src = &frag_shader_src;
int v_src_len_ptr[1] = { strlen(vert_shader_src) };
int f_src_len_ptr[1] = { strlen(frag_shader_src) };
glShaderSource(vshade, 1, v_src, v_src_len_ptr);
glShaderSource(fshade, 1, f_src, f_src_len_ptr);
glCompileShader(vshade);
glCompileShader(fshade);
GLint success;
glGetShaderiv(vshade, GL_COMPILE_STATUS, &success);
if (!success) {
GLchar infolog[1024];
glGetShaderInfoLog(vshade, sizeof(infolog), NULL, infolog);
fprintf(stderr, "Err compiling shader: '%s'\n", infolog); }
glGetShaderiv(fshade, GL_COMPILE_STATUS, &success);
if (!success) {
GLchar infolog[1024];
glGetShaderInfoLog(fshade, sizeof(infolog), NULL, infolog);
fprintf(stderr, "Err compiling shader: '%s'\n", infolog); }
glAttachShader(prog, vshade);
glAttachShader(prog, fshade);
glLinkProgram(prog);
glGetProgramiv(prog, GL_LINK_STATUS, &success);
if (!success) {
GLchar infolog[1024];
glGetProgramInfoLog(prog, sizeof(infolog), NULL, infolog);
fprintf(stderr, "Error linking shader program: '%s'\n", infolog); }
glValidateProgram(prog);
glGetProgramiv(prog, GL_VALIDATE_STATUS, &success);
if (!success) {
GLchar infolog[1024];
glGetProgramInfoLog(prog, sizeof(infolog), NULL, infolog);
fprintf(stderr, "Error validating shader program: '%s'\n", infolog); }
glDeleteShader(vshade);
glDeleteShader(fshade);
return 1; }
int main(int argc, char **argv) {
initGlut(&argc, argv, render);
// GL_GetError throws 1280 (invalid enum) after glewInit but all say it's OK
if(glewInit() != GLEW_OK) {
puts("GLEW failed to initialize!");
return EXIT_FAILURE; }
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
initProg();
glutMainLoop();
glDeleteProgram(prog);
glDeleteBuffers(1, &VBO);
return EXIT_SUCCESS; }
By the way, I've downloaded this Github repo of minimal OpenGL 3.3 example and it works just fine. The only major difference I saw there was the use of VAO in addition to VBO.
EDIT: added VAO, ported to GLFW - still same issue.
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
GLuint VBO;
GLuint VAO;
GLuint prog;
const GLchar *vert_shader_src =
"#version 330\n"
"layout (location = 0) in vec3 Position;\n"
"void main() {\n"
"gl_Position = vec4(0.5*Position.x, 0.5*Position.y, Position.z, 1.0); }\n";
const GLchar *frag_shader_src =
"#version 330\n"
"out vec4 FragColor;\n"
"void main() {\n"
"FragColor = vec4(1.0, 0.0, 0.0, 1.0); }";
void render(GLFWwindow *window) {
glClear(GL_COLOR_BUFFER_BIT);
glUseProgram(prog);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
glDrawArrays(GL_TRIANGLES, 0, 3);
glDisableVertexAttribArray(0);
glfwSwapBuffers(window); }
void initVBO(void) {
float pts[9] = {-1.0f, -1.0f, 0.0f, 1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f};
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(pts), pts, GL_STATIC_DRAW); }
int initProg(void) {
prog = glCreateProgram();
GLuint vshade = glCreateShader(GL_VERTEX_SHADER);
GLuint fshade = glCreateShader(GL_FRAGMENT_SHADER);
const GLchar **v_src = &vert_shader_src;
const GLchar **f_src = &frag_shader_src;
int v_src_len_ptr[1] = { strlen(vert_shader_src) };
int f_src_len_ptr[1] = { strlen(frag_shader_src) };
glShaderSource(vshade, 1, v_src, v_src_len_ptr);
glShaderSource(fshade, 1, f_src, f_src_len_ptr);
glCompileShader(vshade);
glCompileShader(fshade);
GLint success;
glGetShaderiv(vshade, GL_COMPILE_STATUS, &success);
if (!success) {
GLchar infolog[1024];
glGetShaderInfoLog(vshade, sizeof(infolog), NULL, infolog);
fprintf(stderr, "Err compiling shader: '%s'\n", infolog); }
glGetShaderiv(fshade, GL_COMPILE_STATUS, &success);
if (!success) {
GLchar infolog[1024];
glGetShaderInfoLog(fshade, sizeof(infolog), NULL, infolog);
fprintf(stderr, "Err compiling shader: '%s'\n", infolog); }
glAttachShader(prog, vshade);
glAttachShader(prog, fshade);
glLinkProgram(prog);
glGetProgramiv(prog, GL_LINK_STATUS, &success);
if (!success) {
GLchar infolog[1024];
glGetProgramInfoLog(prog, sizeof(infolog), NULL, infolog);
fprintf(stderr, "Error linking shader program: '%s'\n", infolog); }
glValidateProgram(prog);
glGetProgramiv(prog, GL_VALIDATE_STATUS, &success);
if (!success) {
GLchar infolog[1024];
glGetProgramInfoLog(prog, sizeof(infolog), NULL, infolog);
fprintf(stderr, "Error validating shader program: '%s'\n", infolog); }
glDeleteShader(vshade);
glDeleteShader(fshade);
return 1; }
int main() {
if(!glfwInit()) {
puts("GLFW failed to initialize!");
return EXIT_FAILURE; }
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow *window = glfwCreateWindow(640, 480, "My Title", NULL, NULL);
if(window == NULL) {
puts("Failed to create window!");
glfwTerminate();
return EXIT_FAILURE; }
glfwMakeContextCurrent(window);
if(glewInit() != GLEW_OK) {
puts("GLEW failed to initialize!");
glfwDestroyWindow(window);
glfwTerminate();
return EXIT_FAILURE; }
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
initProg();
while(!glfwWindowShouldClose(window)) {
render(window); }
glDeleteProgram(prog);
glDeleteBuffers(1, &VBO);
glfwDestroyWindow(window);
glfwTerminate();
return EXIT_SUCCESS; }
It turns out I created a function to initialize VBO and VAO... but forgot to call it. For two days.
I'm learning OpenGL from this tutorial: http://openglbook.com/the-book/ . I have problem with shaders. I'm getting error during compiling/linking shaders but I don't know what I'm doing wrong.
Error:
Symbol ex_Color is defined with 2 different types in vertex and
fragment shaders.
Shaders (I modified them a bit because of GLSL version):
const GLchar* VertexShader =
{
"#version 130\n"\
"in vec4 in_Position;\n"\
"in vec4 in_Color;\n"\
"out vec4 ex_Color;\n"\
"void main(void)\n"\
"{\n"\
" gl_Position = in_Position;\n"\
" ex_Color = in_Color;\n"\
"}\n"
};
const GLchar* FragmentShader =
{
"#version 130\n"\
"precision mediump float;\n"\
"in vec4 ex_Color;\n"\
"out vec4 out_Color;\n"\
"void main(void)\n"\
"{\n"\
" out_Color = ex_Color;\n"\
"}\n"
};
Source code:
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <GL/glew.h>
#include <GL/freeglut.h>
#define WINDOW_TITLE_PREFIX "Chapter 2"
int CurrentWidth = 800,
CurrentHeight = 600,
WindowHandle = 0;
unsigned FrameCount = 0;
GLuint
VertexShaderId,
FragmentShaderId,
ProgramId,
VaoId,
VboId,
ColorBufferId;
const GLchar* VertexShader =
{
"#version 130\n"\
"in vec4 in_Position;\n"\
"in vec4 in_Color;\n"\
"out vec4 ex_Color;\n"\
"void main(void)\n"\
"{\n"\
" gl_Position = in_Position;\n"\
" ex_Color = in_Color;\n"\
"}\n"
};
const GLchar* FragmentShader =
{
"#version 130\n"\
"precision mediump float;\n"\
"in vec4 ex_Color;\n"\
"out vec4 out_Color;\n"\
"void main(void)\n"\
"{\n"\
" out_Color = ex_Color;\n"\
"}\n"
};
void Initialize(int, char*[]);
void InitWindow(int, char*[]);
void ResizeFunction(int, int);
void RenderFunction(void);
void TimerFunction(int);
void IdleFunction(void);
void Cleanup(void);
void CreateVBO(void);
void DestroyVBO(void);
void CreateShaders(void);
void DestroyShaders(void);
int main(int argc, char* argv[])
{
Initialize(argc, argv);
glutMainLoop();
exit(EXIT_SUCCESS);
}
void Initialize(int argc, char* argv[])
{
GLenum GlewInitResult;
InitWindow(argc, argv);
glewExperimental = GL_TRUE;
GlewInitResult = glewInit();
if (GLEW_OK != GlewInitResult) {
fprintf(
stderr,
"ERROR: %s\n",
glewGetErrorString(GlewInitResult)
);
exit(EXIT_FAILURE);
}
fprintf(
stdout,
"INFO: OpenGL Version: %s (GLSL = %s)\n",
glGetString(GL_VERSION),
glGetString(GL_SHADING_LANGUAGE_VERSION)
);
CreateShaders();
CreateVBO();
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
}
void InitWindow(int argc, char* argv[])
{
glutInit(&argc, argv);
glutInitContextVersion(3, 1);
glutInitContextFlags(GLUT_FORWARD_COMPATIBLE);
glutInitContextProfile(GLUT_CORE_PROFILE);
glutSetOption(
GLUT_ACTION_ON_WINDOW_CLOSE,
GLUT_ACTION_GLUTMAINLOOP_RETURNS
);
glutInitWindowSize(CurrentWidth, CurrentHeight);
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
WindowHandle = glutCreateWindow(WINDOW_TITLE_PREFIX);
if(WindowHandle < 1) {
fprintf(
stderr,
"ERROR: Could not create a new rendering window.\n"
);
exit(EXIT_FAILURE);
}
glutReshapeFunc(ResizeFunction);
glutDisplayFunc(RenderFunction);
glutIdleFunc(IdleFunction);
glutTimerFunc(0, TimerFunction, 0);
glutCloseFunc(Cleanup);
}
void ResizeFunction(int Width, int Height)
{
CurrentWidth = Width;
CurrentHeight = Height;
glViewport(0, 0, CurrentWidth, CurrentHeight);
}
void RenderFunction(void)
{
++FrameCount;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0, 3);
glutSwapBuffers();
glutPostRedisplay();
}
void IdleFunction(void)
{
glutPostRedisplay();
}
void TimerFunction(int Value)
{
if (0 != Value) {
char* TempString = (char*)
malloc(512 + strlen(WINDOW_TITLE_PREFIX));
sprintf(
TempString,
"%s: %d Frames Per Second # %d x %d",
WINDOW_TITLE_PREFIX,
FrameCount * 4,
CurrentWidth,
CurrentHeight
);
glutSetWindowTitle(TempString);
free(TempString);
}
FrameCount = 0;
glutTimerFunc(250, TimerFunction, 1);
}
void Cleanup(void)
{
DestroyShaders();
DestroyVBO();
}
void CreateVBO(void)
{
GLfloat Vertices[] = {
-0.8f, -0.8f, 0.0f, 1.0f,
0.0f, 0.8f, 0.0f, 1.0f,
0.8f, -0.8f, 0.0f, 1.0f
};
GLfloat Colors[] = {
1.0f, 0.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
0.0f, 0.0f, 1.0f, 1.0f
};
GLenum ErrorCheckValue = glGetError();
glGenVertexArrays(1, &VaoId);
glBindVertexArray(VaoId);
glGenBuffers(1, &VboId);
glBindBuffer(GL_ARRAY_BUFFER, VboId);
glBufferData(GL_ARRAY_BUFFER, sizeof(Vertices), Vertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0);
glEnableVertexAttribArray(0);
glGenBuffers(1, &ColorBufferId);
glBindBuffer(GL_ARRAY_BUFFER, ColorBufferId);
glBufferData(GL_ARRAY_BUFFER, sizeof(Colors), Colors, GL_STATIC_DRAW);
glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 0, 0);
glEnableVertexAttribArray(1);
ErrorCheckValue = glGetError();
if (ErrorCheckValue != GL_NO_ERROR)
{
fprintf(
stderr,
"ERROR: Could not create a VBO: %s \n",
gluErrorString(ErrorCheckValue)
);
exit(-1);
}
}
void DestroyVBO(void)
{
GLenum ErrorCheckValue = glGetError();
glDisableVertexAttribArray(1);
glDisableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glDeleteBuffers(1, &ColorBufferId);
glDeleteBuffers(1, &VboId);
glBindVertexArray(0);
glDeleteVertexArrays(1, &VaoId);
ErrorCheckValue = glGetError();
if (ErrorCheckValue != GL_NO_ERROR)
{
fprintf(
stderr,
"ERROR: Could not destroy the VBO: %s \n",
gluErrorString(ErrorCheckValue)
);
exit(-1);
}
}
void CreateShaders(void)
{
GLenum ErrorCheckValue = glGetError();
VertexShaderId = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(VertexShaderId, 1, &VertexShader, NULL);
glCompileShader(VertexShaderId);
GLint vertex_shader_status;
glGetShaderiv(FragmentShaderId, GL_COMPILE_STATUS, &vertex_shader_status);
if (vertex_shader_status == 0)
{
GLint logLength;
glGetShaderiv(FragmentShaderId, GL_INFO_LOG_LENGTH, &logLength);
if (logLength > 0)
{
GLchar *log = (GLchar *)malloc(logLength);
glGetShaderInfoLog(FragmentShaderId, logLength, &logLength, log);
fprintf(
stderr,
"ERROR: Could not create the vertex shader: %s \n",
log
);
free(log);
}
glDeleteShader(FragmentShaderId);
}
FragmentShaderId = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(FragmentShaderId, 1, &FragmentShader, NULL);
glCompileShader(FragmentShaderId);
ProgramId = glCreateProgram();
glAttachShader(ProgramId, VertexShaderId);
glAttachShader(ProgramId, FragmentShaderId);
glBindAttribLocation(ProgramId, 0, "in_Position");
glBindAttribLocation(ProgramId, 1, "in_Color");
glLinkProgram(ProgramId);
glUseProgram(ProgramId);
GLint logLength, status;
glValidateProgram(ProgramId);
glGetProgramiv(ProgramId, GL_INFO_LOG_LENGTH, &logLength);
if (logLength > 0)
{
GLchar *log = (GLchar *)malloc(logLength);
glGetProgramInfoLog(ProgramId, logLength, &logLength, log);
fprintf(
stderr,
"ERROR: Could not create the program: %s \n",
log
);
free(log);
}
glGetProgramiv(ProgramId, GL_VALIDATE_STATUS, &status);
if (status == 0) {
fprintf(
stderr,
"ERROR: Could not create the program: \n"
);
}
ErrorCheckValue = glGetError();
if (ErrorCheckValue != GL_NO_ERROR)
{
fprintf(
stderr,
"ERROR: Could not create the shaders: %s \n",
gluErrorString(ErrorCheckValue)
);
exit(-1);
}
}
void DestroyShaders(void)
{
GLenum ErrorCheckValue = glGetError();
glUseProgram(0);
glDetachShader(ProgramId, VertexShaderId);
glDetachShader(ProgramId, FragmentShaderId);
glDeleteShader(FragmentShaderId);
glDeleteShader(VertexShaderId);
glDeleteProgram(ProgramId);
ErrorCheckValue = glGetError();
if (ErrorCheckValue != GL_NO_ERROR)
{
fprintf(
stderr,
"ERROR: Could not destroy the shaders: %s \n",
gluErrorString(ErrorCheckValue)
);
exit(-1);
}
}
I have Mobility Radeon HD4570 graphics card (OpenGL 3.1, GLSL 1.30).
"precision mediump float;" changes the type of all floats defined in that shader. Is there a reason you're using that declaration? Note that GLSL per specification attaches no meaning to it at all. It was added for compatibility with GLES.
If I'm not mistaken then floats by default have highp precision in vertex shader. Add mediump to out vec ex_Color in vertex shader.