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#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <SDL2/SDL.h>
#define WINDOW_W 1280
#define WINDOW_H 720
#define WALK_VEL 20
static inline double GetCurrentTimestamp() {
return (double) SDL_GetTicks64() / 1000.0;
}
SDL_Texture *CreateTiledTexture(SDL_Renderer *context, const char *filename, int width, int height) {
SDL_Surface *texture_surface = SDL_LoadBMP(filename);
SDL_Texture *texture_tile = SDL_CreateTextureFromSurface(context, texture_surface);
int tile_w = texture_surface->w;
int tile_h = texture_surface->h;
SDL_FreeSurface(texture_surface);
SDL_Texture *texture = SDL_CreateTexture(context,
SDL_PIXELFORMAT_RGBA8888,
SDL_TEXTUREACCESS_TARGET,
width, height);
SDL_SetRenderTarget(context, texture);
for (int y = 0; y < height; y += tile_h) {
for (int x = 0; x < width; x += tile_w) {
SDL_Rect tile_rect = { x, y, tile_w, tile_h };
SDL_RenderCopy(context, texture_tile, 0, &tile_rect);
}
}
SDL_DestroyTexture(texture_tile);
SDL_SetRenderTarget(context, 0);
return texture;
}
void PaintMask(float *mask, int width, int height, float x, float y, float color, float size) {
for (int j = y - size; j < y + size; j++) {
for (int i = x - size; i < x + size; i++) {
float dj = y - j;
float di = x - i;
if (i > 0 && i < width && j > 0 && j < height
&& dj * dj + di * di <= size * size / 2) {
size_t index = i + j * width;
mask[index] = color;
}
}
}
}
void GameMain(SDL_Renderer *context) {
SDL_Texture *background = CreateTiledTexture(context, "background.bmp", WINDOW_W, WINDOW_H);
SDL_Texture *foreground = CreateTiledTexture(context, "foreground.bmp", WINDOW_W, WINDOW_H);
SDL_SetTextureBlendMode(foreground, SDL_BLENDMODE_MOD);
SDL_Texture *terrain = SDL_CreateTexture(context,
SDL_PIXELFORMAT_RGBA8888,
SDL_TEXTUREACCESS_TARGET,
WINDOW_W, WINDOW_H);
SDL_SetTextureBlendMode(terrain, SDL_BLENDMODE_BLEND);
SDL_Texture *mask_texture = SDL_CreateTexture(context,
SDL_PIXELFORMAT_RGBA8888,
SDL_TEXTUREACCESS_STREAMING,
WINDOW_W, WINDOW_H);
float *mask = calloc(WINDOW_W * WINDOW_H, sizeof(float));
for (int i = 0; i < 100 * WINDOW_W; i++) {
mask[i] = 1.0;
}
float player_x = 100;
float player_y = 500;
float player_vy = 0;
float player_ay = -9.8;
float old_t = 0.0;
int exit = 0;
while (!exit) {
double new_t = GetCurrentTimestamp();
double dt = (new_t - old_t) * 10;
old_t = new_t;
SDL_Event event;
while (SDL_PollEvent(&event)) {
if (event.type == SDL_QUIT) {
exit = 1;
}
}
int mouse_x, mouse_y;
Uint32 mouse_state = SDL_GetMouseState(&mouse_x, &mouse_y);
float size = 20;
if (mouse_state & SDL_BUTTON_LMASK) {
PaintMask(mask, WINDOW_W, WINDOW_H, mouse_x, WINDOW_H - mouse_y, 1.0, size);
} else if (mouse_state & SDL_BUTTON_RMASK) {
PaintMask(mask, WINDOW_W, WINDOW_H, mouse_x, WINDOW_H - mouse_y, 0.0, size);
}
const Uint8 *keys = SDL_GetKeyboardState(0);
if (keys[SDL_SCANCODE_D]) {
player_x += WALK_VEL * dt;
}
if (keys[SDL_SCANCODE_A]) {
player_x -= WALK_VEL * dt;
}
if (player_x < 0) {
player_x += WALK_VEL * dt;
} else if (player_x >= WINDOW_W) {
player_x -= WALK_VEL * dt;
}
if (player_y >= WINDOW_H) {
player_y = WINDOW_H - 1;
player_vy = 0;
}
if (mask[(int)player_x + (int)player_y * WINDOW_W] == 0.0 &&
player_y >= 0) {
player_y += player_vy * dt;
player_vy += player_ay * dt;
while (mask[(int)player_x + (int)player_y * WINDOW_W] != 0.0) {
player_y += 1;
player_vy = 0;
}
}
void *pixels;
int pitch;
SDL_LockTexture(mask_texture, 0, &pixels, &pitch);
Uint32 *p = (Uint32 *) pixels;
for (int j = 0; j < WINDOW_H; j++) {
for (int i = 0; i < WINDOW_W; i++) {
p[i + j * WINDOW_W] = mask[i + (WINDOW_H - j) * WINDOW_W] ? 0xffffffff : 0x00000000;
}
}
SDL_UnlockTexture(mask_texture);
SDL_SetRenderDrawColor(context, 40, 40, 40, 255);
SDL_RenderClear(context);
SDL_RenderCopy(context, background, 0, 0);
SDL_SetRenderTarget(context, terrain);
SDL_SetRenderDrawColor(context, 0, 0, 0, 0);
SDL_RenderClear(context);
SDL_RenderCopy(context, mask_texture, 0, 0);
SDL_RenderCopy(context, foreground, 0, 0);
SDL_SetRenderTarget(context, 0);
SDL_RenderCopy(context, terrain, 0, 0);
SDL_SetRenderDrawColor(context, 255, 0, 0, 255);
SDL_Rect player_rect = {player_x - 5, WINDOW_H - player_y - 10, 10, 10 };
SDL_RenderFillRect(context, &player_rect);
SDL_RenderPresent(context);
SDL_Delay(1);
}
}
int main() {
SDL_Init(SDL_INIT_VIDEO);
SDL_Window *window = SDL_CreateWindow("Cannons",
SDL_WINDOWPOS_UNDEFINED,
SDL_WINDOWPOS_UNDEFINED,
WINDOW_W,
WINDOW_H,
0);
SDL_Renderer *context = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
GameMain(context);
SDL_DestroyRenderer(context);
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}
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