Can someone help me to increase the length of the snake and make it follow the head ?
I tried to develop a simple snake game without videos or help and did almost great but cannot figure out how to increase the size of the snake and move it properly.
I'd be very thankful
#include <SDL2/SDL.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>
#include <time.h>
#define LOG(x) printf("%s\n", x)
#define LOG_ERROR(x) fprintf(stderr, "Error: %s\n", x)
#define LOG_SDL_ERROR(x) fprintf(stderr, "%s: %s\n", x, SDL_GetError())
#define global_variable static
#define internal_function static
#define SCREEN_WIDTH 640
#define SCREEN_HEIGHT 480
#define HEAD_SIZE 30
#define APPLE_SIZE 25
#define MAX_LENGHT 10
typedef const char* string;
typedef float realNum;
typedef struct Snake
{
SDL_Rect body[MAX_LENGHT];
int xSpeed;
int ySpeed;
int site;
realNum xPos;
realNum yPos;
} Snake;
typedef struct Apple
{
int xPos;
int yPos;
int size;
} Apple;
void checkColissions(Apple *apple, Snake *snake );
bool initGame(void);
void update(realNum);
void handleEvent(SDL_Event);
void renderGame(void);
void gameOver(void);
void shutdownGame(void);
Snake makeSnake(void);
void renderSnake(Snake *snake);
void updateSnake(Snake *, realNum);
Apple makeApple();
void renderApple(Apple *);
global_variable bool Running;
global_variable SDL_Window *g_pWindow;
global_variable SDL_Renderer *g_pRenderer;
Snake *g_pSnake = NULL;
Apple *g_pApple = NULL;
int
main(int argc, char const *argv[])
{
srand((unsigned int)time(NULL));
atexit(shutdownGame);
if (!initGame())
{
LOG_ERROR("Failed Initialization");
exit(1);
}
else
{
Running = true;
int fps = 330;
int desiredDelta = 1000/fps;
SDL_Event event;
while (Running)
{
renderGame();
update(desiredDelta);
handleEvent(event);
SDL_Delay(rand() % 30);
}
}
return (EXIT_SUCCESS);
}
bool
initGame()
{
if (SDL_Init(SDL_INIT_VIDEO) != 0)
{
LOG_SDL_ERROR("Failed initialization: ");
return (false);
}
else
{
g_pWindow =
SDL_CreateWindow("Snake", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
g_pRenderer =
SDL_CreateRenderer(g_pWindow, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
g_pSnake = (Snake*)malloc(sizeof(Snake));
g_pApple = (Apple*)malloc(sizeof(Apple));
*g_pSnake = makeSnake();
*g_pApple = makeApple();
if ((g_pApple || g_pSnake || g_pRenderer || g_pWindow) == NULL)
{
return (false);
}
g_pWindow == NULL ? LOG_ERROR("Window failed") : LOG("Succes Window");
g_pRenderer == NULL ? LOG_ERROR("Renderer failed") : LOG("Succes Renderer");
g_pApple == NULL ? LOG_ERROR("Apple failed") : LOG("Succes Apple");
g_pSnake == NULL ? LOG_ERROR("Snake failed") : LOG("Succes Snake");
LOG("Game initialized");
}
return true;
}
void
renderGame()
{
SDL_SetRenderDrawColor(g_pRenderer, 0, 80, 0, 255);
SDL_RenderClear(g_pRenderer);
renderSnake(g_pSnake);
renderApple(g_pApple);
SDL_RenderPresent(g_pRenderer);
}
void update(realNum elapsed)
{
updateSnake(g_pSnake, elapsed);
checkColissions(g_pApple, g_pSnake);
}
void
handleEvent(SDL_Event event)
{
SDL_PollEvent(&event);
switch (event.type)
{
case SDL_QUIT:
{
Running = false;
} break;
default:
break;
}
}
void
shutdownGame()
{
if (g_pWindow)
{
SDL_DestroyWindow(g_pWindow);
}
if (g_pRenderer)
{
SDL_DestroyRenderer(g_pRenderer);
}
if (g_pApple)
{
free(g_pApple);
}
if (g_pSnake)
{
free(g_pSnake);
}
SDL_Quit();
LOG("Game shutdowned");
}
Snake makeSnake(void)
{
const int speed = 0;
Snake snake = {
.xSpeed = speed,
.ySpeed = speed,
.xPos = SCREEN_WIDTH / 2,
.yPos = SCREEN_HEIGHT / 2,
.site = HEAD_SIZE
};
SDL_Rect SnakeRect = {
.h = snake.site,
.w = snake.site,
.x = snake.xPos,
.y = snake.yPos
};
snake.body[0] = SnakeRect;
return (snake);
}
void renderSnake(Snake *snake)
{
for (int i = 0; i < MAX_LENGHT; i++)
{
SDL_SetRenderDrawColor(g_pRenderer, 0, 0, 100, 255);
SDL_RenderFillRect(g_pRenderer, &snake->body[i]);
}
}
void updateSnake(Snake *snake, realNum elapsed)
{
const Uint8 *keyboardState = SDL_GetKeyboardState(NULL);
for (int i = 0; i < MAX_LENGHT; i++)
{
/* code */
snake->body[i].y += snake->ySpeed * elapsed;
snake->body[i].x += snake->xSpeed * elapsed;
}
/* code */
/* code */
/* code */
if (keyboardState[SDL_SCANCODE_W])
{
snake->ySpeed = -1;
snake->xSpeed = 0;
}
if (keyboardState[SDL_SCANCODE_D])
{
snake->ySpeed = 0;
snake->xSpeed = 1;
}
if (keyboardState[SDL_SCANCODE_A])
{
snake->ySpeed = 0;
snake->xSpeed = -1;
}
if (keyboardState[SDL_SCANCODE_S])
{
snake->ySpeed = 1;
snake->xSpeed = 0;
}
if (snake->body->x < 0 - HEAD_SIZE)
{
snake->body->x = SCREEN_WIDTH + HEAD_SIZE;
}
if (snake->body->x > SCREEN_WIDTH + HEAD_SIZE)
{
snake->body->x = 0 - HEAD_SIZE;
}
if (snake->body->y < 0 - HEAD_SIZE)
{
snake->body->y = SCREEN_HEIGHT + HEAD_SIZE;
}
if (snake->body->y > SCREEN_HEIGHT + HEAD_SIZE)
{
snake->body->y = 0 - HEAD_SIZE;
}
}
void
checkColissions(Apple *apple, Snake *snake )
{
SDL_Rect appleRect = {
.h = APPLE_SIZE,
.w = APPLE_SIZE,
.x = apple->xPos,
.y = apple->yPos
};
if (SDL_HasIntersection(&appleRect, snake->body))
{
*g_pApple = makeApple();
};
}
Can someone help me to increase the length of the snake and make it follow the head ?
Snake is defined by an array of coordinates, not just one (x,y). You need some kind of circular buffer, that can change capacity. Or you can just use an array, and then change every element of the array with every snake's move. And then you would realize that circular buffer is a really neat idea.
Once you have your buffer, be it an array or circular buffer, the question becomes how to move and enlarge the snake in it. It is simple. To move the snake you add one coordinate to the head, and remove one from the tail of the buffer. When the snake should become bigger you just don't remove the last element in the buffer. Add to the head, but don't remove the tail. This is how circular buffer would be handled. In case of a plain array moving means overwriting everything, and enlarging means adding to the beginning, and moving everything else by one place.
Related
I am working on an object of SDL Tetris. When I ran my code, it first worked fine. But it automatically stopped displaying my text a few minutes later. I guessed there must be some problem on the memory management and I proved that I was right via Task Manager.
I look over my source code but found nothing wrong. (at least I didn't find it) Every heap object I delcared was freed and textures were destroyed. So, what can be the problem?
Here's my source code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <time.h>
#include <stdbool.h>
#define SDL_MAIN_HANDLED
#include <SDL2/SDL.h>
#include <SDL2/SDL_ttf.h>
SDL_Window * window;
SDL_Renderer * renderer;
SDL_Surface * text;
TTF_Font* font;
bool running = true;
#define ScreenWidth 60
#define ScreenHeight 30
#define CharWidth 14
#define CharHeight 24
char screen[ScreenHeight][ScreenWidth + 1];
SDL_Color color = {192, 192, 192};
SDL_Rect rect;
int score = 0;
char shapes[7][17];
typedef struct Block {
int type;
char shape[17];
int x, y;
int width, height;
} Block;
Block * newBlock(int type) {
Block * block = malloc(sizeof(Block));
return block;
}
void CheckEvents() {
SDL_Event event;
while (SDL_PollEvent(&event)) {
if (event.type == SDL_QUIT) {
running = false;
} else if (event.type == SDL_KEYDOWN) {
switch (event.key.keysym.sym) {
case SDLK_w:
;
break;
case SDLK_a:
;
break;
case SDLK_d:
;
break;
case SDLK_s:
;
break;
case SDLK_SPACE:
;
break;
default:
break;
}
}
}
free(&event);
}
void UpdateBoard() {
for (int i = 0; i < ScreenHeight; ++i) {
for (int j = 0; j < ScreenWidth; ++j) {
screen[i][j] = ' ';
}
}
for (int i = 0; i != 20; ++i) {
screen[i + 2][1] = '#';
screen[i + 2][1 + 10 + 1] = '#';
}
for (int i = 0; i != 10 + 2; ++i) {
screen[22][i + 1] = '#';
}
sprintf(&(screen[0][1]), "Score: %d", score);
for (int i = 0; i != ScreenHeight; i++) {
for (int j = 0; j != ScreenWidth; j++) {
if (screen[i][j] == '\0') {
screen[i][j] = ' ';
}
}
}
}
void UpdateScreen() {
SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
SDL_RenderClear(renderer);
for (int i = 0; i < ScreenHeight; ++i) {
text = TTF_RenderText_Solid(font, screen[i], color);
SDL_Texture * texture;
texture = SDL_CreateTextureFromSurface(renderer, text);
rect.x = 0;
rect.y = i * CharHeight;
rect.w = strlen(screen[i]) * CharWidth;
rect.h = CharHeight;
SDL_RenderCopy(renderer, texture, NULL, &rect);
free(texture);
SDL_DestroyTexture(texture);
}
SDL_RenderPresent(renderer);
}
void Init() {
SDL_Init(SDL_INIT_EVERYTHING);
TTF_Init();
window = SDL_CreateWindow("Tetris", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
ScreenWidth * CharWidth, ScreenHeight * CharHeight, 0);
renderer = SDL_CreateRenderer(window, -1, 0);
font = TTF_OpenFont("s8514oem.fon", 0);
sprintf(shapes[0], "OOOO............");
sprintf(shapes[1], "OO...OO.........");
sprintf(shapes[2], ".OO.OO..........");
sprintf(shapes[3], "O...OOO.........");
sprintf(shapes[4], "..O.OOO.........");
sprintf(shapes[5], "OO..OO..........");
sprintf(shapes[6], "OOO..O..........");
}
int main(int argc, char ** argv) {
Init();
while (running) {
CheckEvents();
UpdateBoard();
UpdateScreen();
SDL_Delay(1000/16);
}
TTF_Quit();
SDL_Quit();
return 0;
}
My Makefile:
tetris:
gcc -std=c99 -Wall -Isrc/include -Lsrc/lib -o Tetris main.c -lSDL2main -lSDL2 -lSDL2_ttf
Several things:
Don't try to free() stack-allocated variables like event:
//free(&event);
text needs to be freed with SDL_FreeSurface() before replacing its pointer value with a new one from TTF_RenderText_Solid():
if(text) {
SDL_FreeSurface(text);
}
text = TTF_RenderText_Solid(font, screen[i], color);
Don't use free() on the textures returned by SDL_CreateTextureFromSurface(), only use SDL_DestroyTexture():
texture = SDL_CreateTextureFromSurface(renderer, text);
...
//free(texture);
SDL_DestroyTexture(texture);
I'm trying to create a simple camera for my SDL2 platformer with C. However, whenever the player reaches the screen edges, it seems to be cut off by the background. Here is what the player looks like normally:
And here is what the player looks like when it reaches the screen edges:
To make the camera follow the player, I'm just creating a SDL_Rect called camera, setting it to the player x and y positions, and setting the viewport with SDL_RenderSetViewport to the camera rectangle.
Here's the code for that:
void handle_camera() {
SDL_Rect camera = {
.x = WIDTH/2 - player.x - BLOCK_SIZE/2,
.y = HEIGHT/2 - player.y - BLOCK_SIZE/2,
.w = WIDTH,
.h = HEIGHT
};
SDL_RenderSetViewport(game.renderer, &camera);
}
Therefore, I was wondering: what's wrong with my camera function and why is the player being cut off when it gets near the screen edges?
Here is the full code if needed (I organized in functions so I hope it's not too hard to understand):
#include <stdio.h>
#include <stdbool.h>
#include <SDL2/SDL.h>
#define WIDTH 1200
#define HEIGHT 800
#define BLOCK_SIZE 50
#define PLATFORM_AMOUNT 11 //This makes sure there are enough iterations of the loop, and also allocates enough memory for the 2D array of platforms.
#define LAVA_AMOUNT 2
#define TRAMPOLINE_AMOUNT 1
//Prototyping Functions
int initialize();
void handle_input();
void draw_player();
void player_moveX();
void player_moveY();
void checkCollisionsX();
void checkCollisionsY();
int rectCollide();
void drawLevel();
void resetPlayer();
void handle_camera();
typedef struct {
SDL_Renderer *renderer;
SDL_Window *window;
SDL_Surface *surface;
bool running;
int FPS;
bool close_requested;
int input[256];
} Game;
Game game = {
.running = true,
.FPS = 80,
.close_requested = false,
.input = {},
};
typedef struct {
int x;
int y;
double x_vel;
double y_vel;
double x_acc;
double y_acc;
int width;
int height;
double accSpeed;
int maxVel;
double gravity;
double friction;
double jumpForce;
double canJump;
} Player;
Player player = {
.y = HEIGHT-(BLOCK_SIZE*2),
.x = BLOCK_SIZE,
.x_vel = 0,
.y_vel = 0,
.x_acc = 0,
.y_acc = 0,
.width = BLOCK_SIZE,
.height = BLOCK_SIZE,
.accSpeed = 0.15,
.maxVel = 7,
.gravity = 0.5,
.friction = 0.15,
.jumpForce = 15,
.canJump = true,
};
int platforms[PLATFORM_AMOUNT][4] = {
{0, 0, BLOCK_SIZE, HEIGHT}, //WALLS
{0, HEIGHT-BLOCK_SIZE, WIDTH, BLOCK_SIZE},
{400-BLOCK_SIZE, HEIGHT-(BLOCK_SIZE*2), BLOCK_SIZE, BLOCK_SIZE}, //RAMP TO LAVA
{400-BLOCK_SIZE, HEIGHT-(BLOCK_SIZE*3), BLOCK_SIZE, BLOCK_SIZE},
{300, HEIGHT-(BLOCK_SIZE*2), BLOCK_SIZE, BLOCK_SIZE},
{800, HEIGHT-(BLOCK_SIZE*2), BLOCK_SIZE, BLOCK_SIZE},
{800, HEIGHT-(BLOCK_SIZE*3), BLOCK_SIZE, BLOCK_SIZE},
{800+BLOCK_SIZE, HEIGHT-(BLOCK_SIZE*2), BLOCK_SIZE, BLOCK_SIZE},
{WIDTH-BLOCK_SIZE*10, HEIGHT-(BLOCK_SIZE*8), BLOCK_SIZE, BLOCK_SIZE}, //Blocks above lava
{WIDTH-BLOCK_SIZE*8, HEIGHT-(BLOCK_SIZE*10), BLOCK_SIZE, BLOCK_SIZE},
{BLOCK_SIZE, BLOCK_SIZE*3, BLOCK_SIZE*9, BLOCK_SIZE}, //Top platform
};
int lava[LAVA_AMOUNT][4] = {
{400, HEIGHT-(BLOCK_SIZE*3), 400, BLOCK_SIZE*2},
{BLOCK_SIZE*4, BLOCK_SIZE*2, BLOCK_SIZE*3, BLOCK_SIZE},
};
int trampoline[TRAMPOLINE_AMOUNT][4] = {
{WIDTH/2-(BLOCK_SIZE/2), HEIGHT-(BLOCK_SIZE*5), BLOCK_SIZE, BLOCK_SIZE}
};
int main() {
initialize();
while(game.running && !game.close_requested) { //Game loop
SDL_SetRenderDrawColor(game.renderer, 181, 247, 255, 255);
SDL_RenderClear(game.renderer);
handle_input();
handle_camera();
//Collisions only work in this order: playerMoveX, checkCollisionsX, playerMoveY, checkCollisionsY. Then you can draw the platforms and the player.
player_moveX();
checkCollisionsX();
player_moveY();
checkCollisionsY();
drawLevel();
draw_player();
SDL_RenderPresent(game.renderer);
SDL_Delay(1000/game.FPS);
} //End of game loop
SDL_DestroyRenderer(game.renderer);
SDL_DestroyWindow(game.window);
SDL_Quit();
return 0;
}
int initialize() {
if (SDL_Init(SDL_INIT_VIDEO|SDL_INIT_TIMER) != 0) { //return 0 on success
printf("error initializing SDL: %s\n", SDL_GetError());
return 1;
}
game.window = SDL_CreateWindow("Sam's Platformer", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, WIDTH, HEIGHT, SDL_WINDOW_RESIZABLE); //creates window
if (!game.window) {
printf("error creating window: %s\n", SDL_GetError());
SDL_Quit();
return 1;
}
Uint32 render_flags = SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC; //creates a renderer
game.renderer = SDL_CreateRenderer(game.window, -1, render_flags);
if (!game.renderer) {
printf("error creating renderer: %s\n", SDL_GetError());
SDL_DestroyWindow(game.window);
SDL_Quit();
return 1;
}
return 0;
}
void handle_input() {
SDL_Event event;
while (SDL_PollEvent(&event)) {
if (event.type == SDL_QUIT) {
game.close_requested = true;
game.running = false;
}
//printf("input: %p code: %i\n", game.input, event.key.keysym.scancode);
if (event.type == SDL_KEYDOWN) {
game.input[event.key.keysym.scancode] = true;
//printf("True");
}
if (event.type == SDL_KEYUP) {
game.input[event.key.keysym.scancode] = false;
//printf("False");
}
}
if (game.input[SDL_SCANCODE_R]) {
resetPlayer();
}
}
void draw_player() {
SDL_Rect playerRect = {
.x = player.x,
.y = player.y,
.w = player.width,
.h = player.height
};
SDL_SetRenderDrawColor(game.renderer, 0, 200, 50, 255);
SDL_RenderFillRect(game.renderer, &playerRect);
}
void resetPlayer() {
player.y = HEIGHT-(BLOCK_SIZE*2);
player.x = BLOCK_SIZE;
player.x_vel = 0;
player.y_vel = 0;
}
void player_moveX() {
if (game.input[SDL_SCANCODE_LEFT] && player.x_vel > -player.maxVel) {
player.x_acc = -player.accSpeed;
} else if (game.input[SDL_SCANCODE_RIGHT] && player.x_vel < player.maxVel) {
player.x_acc = player.accSpeed;
} else if (abs(player.x_vel) > 0.2) {
if (player.x_vel < 0) {
player.x_acc = player.friction;
} else {
player.x_acc = -player.friction;
}
} else {
player.x_vel = 0;
player.x_acc = 0;
}
player.x_vel += player.x_acc;
player.x += player.x_vel;
}
void player_moveY() {
if (game.input[SDL_SCANCODE_UP] && player.y_vel == 0 && player.y_acc == 0 && player.canJump) {
player.canJump = false;
player.y_vel = -player.jumpForce;
}
player.y_acc += player.gravity;
player.y_vel += player.y_acc;
player.y += player.y_vel;
player.y_acc = 0;
}
void checkCollisionsX() {
for (int i = 0; i < PLATFORM_AMOUNT; i++) {
if (rectCollide(player.x, player.y, BLOCK_SIZE, BLOCK_SIZE, platforms[i][0], platforms[i][1], platforms[i][2], platforms[i][3])) {
if (player.x_vel < 0) { // If the player moved left and collided with the right side of block
player.x = platforms[i][0] + platforms[i][2];
} else { // If the player moved right and collided with the left side of block
player.x = platforms[i][0] - player.width;
}
player.x_vel = 0;
}
}
/*if (player.x >= WIDTH - player.width) {
player.x = WIDTH - player.width;
player.x_vel = 0;
}*/
for (int i = 0; i < LAVA_AMOUNT; i++) {
if (rectCollide(player.x, player.y, BLOCK_SIZE, BLOCK_SIZE, lava[i][0], lava[i][1], lava[i][2], lava[i][3])) {
resetPlayer();
}
}
for (int i = 0; i < TRAMPOLINE_AMOUNT; i++) {
if (rectCollide(player.x, player.y, BLOCK_SIZE, BLOCK_SIZE, trampoline[i][0], trampoline[i][1], trampoline[i][2], trampoline[i][3])) {
if (player.x_vel < 0) { // If the player moved left and collided with the right side of block
player.x = trampoline[i][0] + trampoline[i][2];
} else { // If the player moved right and collided with the left side of block
player.x = trampoline[i][0] - player.width;
}
player.x_vel = 0;
}
}
}
void checkCollisionsY() {
for (int i = 0; i < PLATFORM_AMOUNT; i++) {
if (rectCollide(player.x, player.y, player.width, player.height, platforms[i][0], platforms[i][1], platforms[i][2], platforms[i][3])) {
if (player.y_vel < 0) { // If the player hit their head
player.y = platforms[i][1] + platforms[i][3];
player.y_vel *= -0.5; // Not -1 because collisions are not perfectly elastic
} else {
player.y = platforms[i][1] - player.height;
player.y_vel = 0;
player.y_acc = 0;
player.canJump = true;
}
}
if (player.y >= HEIGHT - player.height) {
player.y_vel = 0;
player.y = HEIGHT - player.height;
if (!game.input[SDL_SCANCODE_UP]) {
player.canJump = true;
}
}
}
for (int i = 0; i < LAVA_AMOUNT; i++) {
if (rectCollide(player.x, player.y, BLOCK_SIZE, BLOCK_SIZE, lava[i][0], lava[i][1], lava[i][2], lava[i][3])) {
resetPlayer();
}
}
for (int i = 0; i < TRAMPOLINE_AMOUNT; i++) {
if (rectCollide(player.x, player.y, BLOCK_SIZE, BLOCK_SIZE, trampoline[i][0], trampoline[i][1], trampoline[i][2], trampoline[i][3])) {
if (player.y_vel < 0) { // If the player hit their head
player.y = trampoline[i][1] + trampoline[i][3];
player.y_vel *= -0.5; // Not -1 because collisions are not perfectly elastic
} else {
player.y = trampoline[i][1] - trampoline[i][3];
player.y_vel = -player.y_vel;
}
}
}
}
int rectCollide(int x1, int y1, int w1, int h1, int x2,int y2, int w2, int h2) {
return x1 + w1 > x2 && x1 < x2 + w2 && y1 + h1 > y2 && y1 < y2 + h2;
}
void drawLevel() {
for (int i = 0; i < PLATFORM_AMOUNT; i++) {
SDL_Rect platform = {platforms[i][0], platforms[i][1], platforms[i][2], platforms[i][3]};
SDL_SetRenderDrawColor(game.renderer, 156, 104, 0, 255);
SDL_RenderFillRect(game.renderer, &platform);
}
for (int i = 0; i < LAVA_AMOUNT; i++) {
int lavaRedColor = 255;
SDL_Rect lavaBlock = {lava[i][0], lava[i][1], lava[i][2], lava[i][3]};
SDL_SetRenderDrawColor(game.renderer, lavaRedColor, 0, 0, 255);
SDL_RenderFillRect(game.renderer, &lavaBlock);
}
for (int i = 0; i < TRAMPOLINE_AMOUNT; i++) {
SDL_Rect trampolineBlock = {trampoline[i][0], trampoline[i][1], trampoline[i][2], trampoline[i][3]};
SDL_SetRenderDrawColor(game.renderer, 235, 52, 229, 255);
SDL_RenderFillRect(game.renderer, &trampolineBlock);
}
}
void handle_camera() {
SDL_Rect camera = {
.x = WIDTH/2 - player.x - BLOCK_SIZE/2,
.y = HEIGHT/2 - player.y - BLOCK_SIZE/2,
.w = WIDTH, //Screen width
.h = HEIGHT //Screen height
};
SDL_RenderSetViewport(game.renderer, &camera);
}
Thanks for any help.
https://gamedev.stackexchange.com/questions/121421/how-to-use-the-sdl-viewport-properly
See this related post. Essentially changing the SDL viewport is not the way you'd typically handle an in game camera. You need to consider drawing your in game entities (level objects etc.) relative to the camera.
I've been working on a game with SDL2 and C, and this is my code so far:
#include <stdio.h>
#include <stdbool.h>
#include <SDL2/SDL.h>
#define BLOCK_SIZE 50
#define SPEED 5
int initialize();
void handle_input();
void draw_player();
typedef struct {
SDL_Renderer *renderer;
SDL_Window *window;
bool running;
int FPS;
int width;
int height;
bool close_requested;
int input[256];
} Game;
Game game = {
.running = true,
.FPS = 60,
.width = 600,
.height = 600,
.close_requested = false,
.input = {},
};
SDL_Rect player = {
.x = 300,
.y = 300,
.w = BLOCK_SIZE,
.h = BLOCK_SIZE
};
int main(int argc, char* argv[]) {
initialize();
while(game.running && !game.close_requested) { //Game loop
SDL_SetRenderDrawColor(game.renderer, 0, 0, 0, 255);
SDL_RenderClear(game.renderer);
handle_input();
draw_player();
SDL_RenderPresent(game.renderer);
SDL_Delay(1000/game.FPS);
} //End of game loop
SDL_DestroyRenderer(game.renderer);
SDL_DestroyWindow(game.window);
SDL_Quit();
return 0;
}
int initialize() {
if (SDL_Init(SDL_INIT_VIDEO|SDL_INIT_TIMER) != 0) { //return 0 on success
printf("error initializing SDL: %s\n", SDL_GetError());
return 1;
}
game.window = SDL_CreateWindow("Window", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, game.width, game.height, 0); //creates window
if (!game.window) {
printf("error creating window: %s\n", SDL_GetError());
SDL_Quit();
return 1;
}
Uint32 render_flags = SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC; //creates a renderer
game.renderer = SDL_CreateRenderer(game.window, -1, render_flags);
if (!game.renderer) {
printf("error creating renderer: %s\n", SDL_GetError());
SDL_DestroyWindow(game.window);
SDL_Quit();
return 1;
}
return 0;
}
void handle_input() {
SDL_Event event;
while (SDL_PollEvent(&event)) {
if (event.type == SDL_QUIT) {
game.close_requested = true;
game.running = false;
}
//printf("input: %p code: %i\n", game.input, event.key.keysym.scancode);
if (event.type == SDL_KEYDOWN) {
game.input[event.key.keysym.scancode] = true;
//printf("True");
}
if (event.type == SDL_KEYUP) {
game.input[event.key.keysym.scancode] = false;
//printf("False");
}
if (game.input[SDL_SCANCODE_UP]) {
player.y -= SPEED;
} else if (game.input[SDL_SCANCODE_DOWN]) {
player.y += SPEED;
} else if (game.input[SDL_SCANCODE_LEFT]) {
player.x -= SPEED;
} else if (game.input[SDL_SCANCODE_RIGHT]) {
player.x += SPEED;
}
}
}
void draw_player() {
SDL_SetRenderDrawColor(game.renderer, 0, 200, 50, 255);
SDL_RenderFillRect(game.renderer, &player);
}
I'm using an array called int input[] within the typedef struct, and within the handle_input() function, I'm using the array like this:
if (event.type == SDL_KEYDOWN) {
game.input[event.key.keysym.scancode] = true;
}
if (event.type == SDL_KEYUP) {
game.input[event.key.keysym.scancode] = false;
}
So that I can easily check if a key is pressed like this:
if (game.input[SDL_SCANCODE_UP]) {
//do something
}
However, when this code is run, the movement is broken up and choppy, and there is a slight delay when you press the key down. I've set the SDL_Delay to 60 FPS, so this shouldn't be an issue with that. The issue must be with the way I'm handling the inputs. Why isn't the input code firing at a consistent and fast rate?
I was working in a University C project (first sem), in which our group wanted to make a simple pong game, we decided to use raylib, as it seemed easy. But here is the problem, in the following code:
void UpdatePad(Pad* pad)
{
int height = GetScreenHeight();
if (IsKeyDown(pad->Scheme.DownButton)) {
printf("Down = %d\n", pad->Scheme.DownButton);
pad->Position.y += GetFrameTime() * pad->Speed;
if ( pad->Position.y + pad->Size.y/2 > height ) {
pad->Position.y = height - pad->Size.y /2;
}
}
if (IsKeyDown(pad->Scheme.UpButton)) {
printf("Up = %d\n", pad->Scheme.UpButton);
pad->Position.y -= GetFrameTime() * pad -> Speed;
if (pad->Position.y - pad->Size.y/2 < 0 ) {
pad->Position.y = pad->Size.y /2;
}
}
}
The function IsKeyDown of raylib always returns true, whatever I do. Even if I replace pad->Scheme.DownButton to KEY_UP or something, it always returns true and executes the code block, Is there any solution for this?
Full script is:
#include <raylib.h>
#include <stdio.h>
#include "pad.h"
#include "main.h"
void DrawPad(Pad* pad);
void UpdatePad(Pad* pad);
void Update();
void DrawUpdate();
void Loop();
int main()
{
int screenWidth = 800;
int screenHeight = 450;
InitWindow(screenWidth, screenHeight, "Table Tennis");
SetTargetFPS(12);
Loop();
return 0;
}
void Loop()
{
while (!WindowShouldClose()) {
DrawUpdate();
}
}
void UpdatePad(Pad* pad)
{
int height = GetScreenHeight();
if (IsKeyDown(pad->Scheme.DownButton)) {
printf("Down = %d\n", pad->Scheme.DownButton);
pad->Position.y += GetFrameTime() * pad->Speed;
if ( pad->Position.y + pad->Size.y/2 > height ) {
pad->Position.y = height - pad->Size.y /2;
}
}
if (IsKeyDown(pad->Scheme.UpButton)) {
printf("Up = %d\n", pad->Scheme.UpButton);
pad->Position.y -= GetFrameTime() * pad -> Speed;
if (pad->Position.y - pad->Size.y/2 < 0 ) {
pad->Position.y = pad->Size.y /2;
}
}
}
void DrawPad(Pad* pad)
{
DrawRectangle(pad->Position.x, pad->Position.y - (pad->Size.y /2), pad->Size.x, pad->Size.y, WHITE);
}
void DrawUpdate()
{
const char* scoreLeft = TextFormat("%d", 10);
int scoreSizeLeft = MeasureText(scoreLeft, 20);
InputScheme Input = { .DownButton = KEY_S, .UpButton = KEY_W };
Vector2 paddySize = { .x = 5, .y = 50 };
Vector2 paddyPos = { .x = GetScreenWidth() - paddySize.x , .y = GetScreenHeight() - paddySize.y };
Pad pad = { .Size = paddySize, .Speed = 50, .Scheme = Input , .Position = paddyPos };
Vector2 from = {.x = (GetScreenWidth() / (float) 2), .y = 5};
Vector2 to = { .x = (GetScreenWidth() / (float) 2), .y = ( GetScreenHeight() - (float) 5 ) };
UpdatePad(&pad);
BeginDrawing();
ClearBackground(BLACK);
DrawLineEx(from, to, 2, LIGHTGRAY);
DrawText(scoreLeft, (GetScreenWidth()/2) - 10 -scoreSizeLeft, 10, 20, LIGHTGRAY);
DrawPad(&pad);
EndDrawing();
}
The pad is:-
#include <raylib.h>
typedef struct {
int UpButton;
int DownButton;
} InputScheme;
typedef struct {
InputScheme Scheme;
int Score;
float Speed;
Vector2 Position;
Vector2 Size;
} Pad;
It's my Code, it's a very simple tank games, I have 2 problems:
use WSAD to move with speed 4, when I pressing and holding shift, the speed change to 8, when I release shift, speed back to 4. But, with my code, when I press shift after holding WSAD, the tank stop, I must repress the key to move it.
When I press WSAD, the tank just change the direction, but not move,so when I holding d, the tank first change it's direction to right for about 0.5 second, then start to move. How to get it move smoothly?
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <stdio.h>
const int WINDOW_WIDTH = 960; //窗体宽度
const int WINDOW_HEIGHT = 640; //窗体高度
//使用旋转角度定义方向
const int UP = 0;
const int DOWN = 180;
const int LEFT = 270;
const int RIGHT = 90;
//-------------------
typedef struct {
int x;
int y;
int width;
int height;
int direction;
SDL_Texture *texture;
} Player;
void RenderPlayer(Player player, SDL_Renderer *renderer) {
SDL_Rect srcRect = {.x = 0, .y = 0, .w = player.width, .h = player.height};
SDL_Rect destRect = {.x = player.x, .y = player.y, .w = player.width / 2, .h = player.height / 2};
SDL_RenderCopyEx(renderer, player.texture, &srcRect, &destRect, player.direction, NULL, SDL_FLIP_NONE);
}
int main(int argc, char *argv[]) {
SDL_Window *window;
SDL_Renderer *renderer;
if (SDL_Init(SDL_INIT_EVERYTHING)) {
printf("SDL对象初始化失败！\n");
return -1;
}
if (!(window = SDL_CreateWindow("坦克大战", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, WINDOW_WIDTH, WINDOW_HEIGHT, SDL_WINDOW_OPENGL))) {
printf("窗体创建失败！\n");
return -1;
}
if (!(renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_TARGETTEXTURE))) {
printf("渲染器创建失败！\n");
return -1;
}
SDL_SetRenderDrawColor(renderer, 76, 110, 150, 255);
SDL_RenderClear(renderer);
SDL_RenderPresent(renderer);
SDL_Surface *surface = IMG_Load("Tank01.png");
if (!surface) {
printf("像素集创建失败：%s\n", IMG_GetError());
return -1;
}
printf("宽度：%d\n高度：%d\n", surface->w, surface->h);
Player player1 = {(WINDOW_WIDTH - surface->w) / 2, WINDOW_HEIGHT - surface->h, surface->w, surface->h, UP, SDL_CreateTextureFromSurface(renderer, surface)};
int speed;
const Uint8 *state = SDL_GetKeyboardState(NULL);
SDL_Event sdlEvent;
while (1) {
int flag1 = 0;
while (SDL_PollEvent(&sdlEvent)) {
speed = 4;
switch (sdlEvent.type) {
case SDL_KEYDOWN:
if (state[SDL_SCANCODE_LSHIFT] && (state[SDL_SCANCODE_W] || state[SDL_SCANCODE_S] || state[SDL_SCANCODE_A] || state[SDL_SCANCODE_D])) {
speed = 8;
}
switch (sdlEvent.key.keysym.sym) {
case SDLK_w:
if (player1.y > 0) {
player1.y -= speed;
}
player1.direction = UP;
break;
case SDLK_s:
if (player1.y < WINDOW_HEIGHT - player1.height / 2) {
player1.y += speed;
}
player1.direction = DOWN;
break;
case SDLK_a:
if (player1.x > 0) {
player1.x -= speed;
}
player1.direction = LEFT;
break;
case SDLK_d:
if (player1.x < WINDOW_WIDTH - player1.width / 2) {
player1.x += speed;
}
player1.direction = RIGHT;
break;
case SDLK_ESCAPE:
SDL_Quit();
flag1 = 1;
break;
}
break;
case SDL_QUIT:
SDL_Quit();
flag1 = 1;
break;
}
}
SDL_RenderClear(renderer);
RenderPlayer(player1, renderer);
SDL_RenderPresent(renderer); //使用渲染器更新窗体
if (flag1) {
break;
}
}
return 0;
}
I couldn't reproduce your first problem with the code you provided, if I hold any of wasd and press shift the tank keeps moving.
The problem here is a bit hard to understand, but you're basically moving the tank only on SDL_Pressed events, meaning that the only reason your tank is moving at all is because SDL repeats the same events over and over, and because it doesn't do this very fast (polling events is kinda slow), your movement is choppy/laggy/steppy whatever you want to call it.
A fix for this is to remove the actual movement step outside your SDL_Event loop, also you should filter out repeat events since you've already checked them.
Meaning your code should look should be something like this
while (1) {
while (SDL_Event(e)) {
if (event is repeated)
skip event
if (UP Key is pressed)
up_state = 1;
if (UP key is released)
up_state = 0;
// etc..
}
// Outside the event loop
if (up_state == 1) // if its 0 we don't add anything
player.x -= speed;
// and so on..
}
For this to work properly you'll also need to read about how to implement a delta time in your loop, because this will run as fast as your processor can meaning that your speed wont be regular, it might add more or less speed depending on how fast is running, which is bad.
Here is your code with these problems fixed, except the delta time, since I actually don't which platform you're on and I was too lazy to do it in C, I capped the framerate at 60fps with a sleep at the end, which is a very bad idea.
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
// I don't know if you're on windows or linux
#ifdef _WIN32
#include <Windows.h>
#else
#include <unistd.h>
#endif
const int WINDOW_WIDTH = 960; //窗体宽度
const int WINDOW_HEIGHT = 640; //窗体高度
//使用旋转角度定义方向
const int UP = 0;
const int DOWN = 180;
const int LEFT = 270;
const int RIGHT = 90;
//-------------------
typedef struct {
int x;
int y;
int width;
int height;
int direction;
SDL_Texture *texture;
} Player;
int m_up = 0;
int m_down = 0;
int m_left = 0;
int m_right = 0;
void RenderPlayer(Player player, SDL_Renderer *renderer) {
SDL_Rect srcRect = {.x = 0, .y = 0, .w = player.width, .h = player.height};
SDL_Rect destRect = {.x = player.x,
.y = player.y,
.w = player.width / 2,
.h = player.height / 2};
SDL_RenderCopyEx(renderer, player.texture, &srcRect, &destRect,
player.direction, NULL, SDL_FLIP_NONE);
}
int main(int argc, char *argv[]) {
SDL_Window *window;
SDL_Renderer *renderer;
if (SDL_Init(SDL_INIT_EVERYTHING)) {
return -1;
}
if (!(window = SDL_CreateWindow("Game", SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED, WINDOW_WIDTH,
WINDOW_HEIGHT, SDL_WINDOW_OPENGL))) {
return -1;
}
if (!(renderer = SDL_CreateRenderer(window, -1,
SDL_RENDERER_ACCELERATED |
SDL_RENDERER_TARGETTEXTURE))) {
return -1;
}
SDL_SetRenderDrawColor(renderer, 76, 110, 150, 255);
SDL_RenderClear(renderer);
SDL_RenderPresent(renderer);
SDL_Surface *surface = IMG_Load("tank.png");
if (!surface) {
return -1;
}
Player player1 = {(WINDOW_WIDTH - surface->w) / 2,
WINDOW_HEIGHT - surface->h,
surface->w,
surface->h,
UP,
SDL_CreateTextureFromSurface(renderer, surface)};
int speed = 4;
SDL_Event sdlEvent;
int run = 1;
while (run) {
while (SDL_PollEvent(&sdlEvent)) {
// Now we skip over repeat events
if ((sdlEvent.type == SDL_KEYDOWN || sdlEvent.type == SDL_KEYUP) &&
sdlEvent.key.repeat == 0) {
SDL_Keycode key = sdlEvent.key.keysym.sym;
int is_pressed = sdlEvent.key.state == SDL_PRESSED;
if (key == SDLK_LSHIFT && is_pressed) {
speed = 8;
} else if (key == SDLK_LSHIFT && !is_pressed) {
speed = 4;
}
if (key == SDLK_w && is_pressed) {
m_up = 1;
} else if (key == SDLK_w) {
m_up = 0;
}
if (key == SDLK_s && is_pressed) {
m_down = 1;
} else if (key == SDLK_s) {
m_down = 0;
}
if (key == SDLK_a && is_pressed) {
m_left = 1;
} else if (key == SDLK_a) {
m_left = 0;
}
if (key == SDLK_d && is_pressed) {
m_right = 1;
} else if (key == SDLK_d) {
m_right = 0;
}
if (key == SDLK_ESCAPE) {
run = 0;
}
if (sdlEvent.type == SDL_QUIT) {
run = 0;
}
}
}
// Handle the movement outside the event loop
if (m_up && player1.y > 0)
player1.y -= speed;
if (m_down && player1.y < WINDOW_HEIGHT - player1.height / 2)
player1.y += speed;
if (m_left && player1.x > 0)
player1.x -= speed;
if (m_right && player1.x < WINDOW_WIDTH - player1.width / 2)
player1.x += speed;
SDL_RenderClear(renderer);
RenderPlayer(player1, renderer);
SDL_RenderPresent(renderer);
#ifdef _WIN32
sleep(0.016); // asume 60 fps, horrible idea
#else
usleep(16000);
#endif
}
SDL_Quit();
return 0;
}
the test image I was using as 'tank.png' https://i.imgur.com/qlUagLp.png