Can't Get Spinning Cube To Render In OpenGL - c

Question

I'm trying to get a spinning 3D cube but I can't get it to render. There's no error, but it's just a black screen. Also, there's no checking whether the Fragment shader is working but I can assure you it is I just don't have it included here.
Here's what my code looks like:
#include <glad/glad.h>
#define GLFW_INCLUDE_NONE
#include <GLFW/glfw3.h>
#include <cglm/cglm.h>
#include <cglm/mat4.h>
#include <cglm/vec3.h>
#include <stdio.h>
#include <stdlib.h>
float vertices[] = {
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f};
GLuint elements[] = {
0, 1, 2,
2, 3, 0};
static const char *vertex_shader_text =
"#version 330 core\n"
"layout (location = 0) in vec3 aPos;\n"
"layout (location = 1) in vec2 aTexCoord;\n"
"out vec2 TexCoord;\n"
"uniform mat4 model;\n"
"uniform mat4 view;\n"
"uniform mat4 projection;\n"
"void main()\n"
"{\n"
" gl_Position = projection * view * model * vec4(aPos, 1.0f);\n"
" TexCoord = vec2(aTexCoord.x, aTexCoord.y);\n"
"}";
static const char *fragment_shader_text =
"#version 330 core\n"
"varying vec3 color;\n"
"void main()\n"
"{\n"
" gl_FragColor = vec4(color, 1.0);\n"
"}\n";
static void error_callback(int error, const char *description) {
fprintf(stderr, "Error: %s\n", description);
}
static void key_callback(GLFWwindow *window, int key, int scancode, int action, int mods) {
if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
glfwSetWindowShouldClose(window, GLFW_TRUE);
}
int main(void) {
GLFWwindow *window;
GLuint vbo, vertex_shader, fragment_shader, program;
GLint mvp_location, vpos_location, vcol_location;
glfwSetErrorCallback(error_callback);
if (!glfwInit())
exit(EXIT_FAILURE);
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
window = glfwCreateWindow(640, 480, "Simple example", NULL, NULL);
if (!window) {
glfwTerminate();
exit(EXIT_FAILURE);
}
glfwSetKeyCallback(window, key_callback);
glfwMakeContextCurrent(window);
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
fprintf(stderr, "Could Not Load GLFW\n");
exit(1);
}
glfwSwapInterval(1);
unsigned int VBO, VAO;
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
// position attribute
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void *)0);
glEnableVertexAttribArray(0);
// texture coord attribute
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void *)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
vertex_shader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
glCompileShader(vertex_shader);
fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
glCompileShader(fragment_shader);
GLint status;
glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &status);
if(!status){
char buffer[512];
glGetShaderInfoLog(vertex_shader, 512, NULL, buffer);
puts(buffer);
}
program = glCreateProgram();
glAttachShader(program, vertex_shader);
glAttachShader(program, fragment_shader);
glLinkProgram(program);
while (!glfwWindowShouldClose(window)) {
float ratio;
int width, height;
glfwGetFramebufferSize(window, &width, &height);
ratio = width / (float)height;
glViewport(0, 0, width, height);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
mat4 model = {{1.f, 1.f, 1.f, 1.f}, {1.f, 1.f, 1.f, 1.f}, {1.f, 1.f, 1.f, 1.f}, {1.f, 1.f, 1.f, 1.f}};
mat4 view = {{1.f, 1.f, 1.f, 1.f}, {1.f, 1.f, 1.f, 1.f}, {1.f, 1.f, 1.f, 1.f}, {1.f, 1.f, 1.f, 1.f}};
mat4 projection = {{1.f, 1.f, 1.f, 1.f}, {1.f, 1.f, 1.f, 1.f}, {1.f, 1.f, 1.f, 1.f}, {1.f, 1.f, 1.f, 1.f}};
vec3 axis = {0.5f, 1.0f, 0.0f};
vec3 dist = {0.0f, 0.0f, -3.0f};
glm_rotate(model, glfwGetTime(), axis);
glm_translate(view, dist);
glm_perspective(0.79, width / height, 0.1f, 100.0f, projection);
unsigned int modelLoc = glGetUniformLocation(program, "model");
unsigned int viewLoc = glGetUniformLocation(program, "view");
glUniformMatrix4fv(modelLoc, 1, GL_FALSE, (const GLfloat *)model);
glUniformMatrix4fv(viewLoc, 1, GL_FALSE, (const GLfloat *)view);
unsigned int projectionLoc = glGetUniformLocation(program, "projection");
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwDestroyWindow(window);
glfwTerminate();
exit(EXIT_SUCCESS);
}

Answer 1

You have to initialize the matrices with the Identity matrix:
mat4 model = {
{1.f, 0.f, 0.f, 0.f},
{0.f, 1.f, 0.f, 0.f},
{0.f, 0.f, 1.f, 0.f},
{0.f, 0.f, 0.f, 1.f}};
Also do so for view and projection.
The data types for the arguments of glm_rotate and glm_perspective must be float:
glm_rotate(model, (float)glfwGetTime(), axis);
glm_translate(view, dist);
glm_perspective((float)0.79, (float)width / (float)height, 0.1f, 100.0f, projection);
You also forgot to create the Index buffer:
glBindVertexArray(VAO);
// [...]
unsigned int IBO;
glGenBuffers(1, &IBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, IBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(elements), elements, GL_STATIC_DRAW);
to install the program:
glUseProgram(program);
to set the projection matrix uniform.
unsigned int projectionLoc = glGetUniformLocation(program, "projection");
glUniformMatrix4fv(projectionLoc, 1, GL_FALSE, (const GLfloat *)projection);
Finally you must change the fragment shader. For example:
#version 330 core
in vec2 TexCoord;
void main()
{
gl_FragColor = vec4(TexCoord.xy, 0.5, 1.0);
};