init

.gitignore

@@ -0,0 +1,2 @@
+*.swp
+bin/

cat_api.h

@@ -0,0 +1,155 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <SDL2/SDL.h>
+
+enum cat_events
+{
+	QUIT,
+	KEYDOWN,
+	KEYUP,
+	MOUSEMOVE,
+	MOUSEDOWN,
+	MOUSEUP
+};
+
+struct cat_event
+{
+	enum cat_events type;
+	char key;
+	unsigned char mouse_button;
+	int mousex;
+	int mousey;
+};
+
+/* SDL stuff */
+static unsigned int* fg_framebuffer = NULL;
+static unsigned int* bg_framebuffer = NULL;
+static unsigned int* comp_framebuffer = NULL;
+static SDL_Window* window = NULL;
+static SDL_Renderer* renderer = NULL;
+static SDL_Texture* texture = NULL;
+static int screen_width = 0;
+static int screen_height = 0;
+
+void cat_pixel(int layer, int visible, int x, int y, unsigned char r, unsigned char g, unsigned char b)
+{
+	if (comp_framebuffer == NULL)
+	{
+		printf("Warning: tried to write a pixel while screen uninitialized\n");
+		return;
+	}
+	if (x >= screen_width || y >= screen_height)
+	{
+		printf("Warning: (%u, %u): coordinate off screen\n", x, y);
+		return;
+	}
+	unsigned int draw_color = (r << 16) + (g << 8) + b;
+	if (visible) draw_color += 0xff000000;
+	if (layer) fg_framebuffer[y * screen_width + x] = draw_color;
+	else bg_framebuffer[y * screen_width + x] = draw_color;
+}
+
+void cat_de_init_screen(void)
+{
+	if (window != NULL) SDL_DestroyWindow(window);
+	window = NULL;
+	renderer = NULL;
+	texture = NULL;
+	free(fg_framebuffer);
+	free(bg_framebuffer);
+	free(comp_framebuffer);
+	fg_framebuffer = NULL; /* this might be redundant */
+	bg_framebuffer = NULL;
+	comp_framebuffer = NULL;
+}
+
+void cat_create_window(int w, int h)
+{
+	screen_width = w;
+	screen_height = h;
+	if (window != NULL || renderer != NULL || texture != NULL) cat_de_init_screen();
+	fg_framebuffer = malloc(screen_width * screen_height * sizeof(unsigned int));
+	bg_framebuffer = malloc(screen_width * screen_height * sizeof(unsigned int));
+	comp_framebuffer = malloc(screen_width * screen_height * sizeof(unsigned int));
+	window = SDL_CreateWindow("cfhfg", SDL_WINDOWPOS_CENTERED,
+		SDL_WINDOWPOS_CENTERED, screen_width, screen_height, SDL_WINDOW_RESIZABLE);
+	renderer = SDL_CreateRenderer(window, -1, 0);
+	texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_ARGB8888,
+		SDL_TEXTUREACCESS_STREAMING, screen_width, screen_height);
+	SDL_ShowCursor(SDL_DISABLE);
+}
+
+void comp_buffers(void)
+{
+	int x, y; for (y = 0; y < screen_height; y++)
+	{
+		for (x = 0; x < screen_width; x++)
+		{
+			if (fg_framebuffer[y * screen_width + x] & 0xff000000)
+				comp_framebuffer[y * screen_width + x] = fg_framebuffer[y * screen_width + x];
+			else comp_framebuffer[y * screen_width + x] = bg_framebuffer[y * screen_width + x] | 0xff000000;
+											/* TODO decide if this should be left
+											   as 0 if "erasing", to make a black
+											   pixel, ignoring other color info */
+		}
+	}
+}
+
+void cat_render(void)
+{
+	comp_buffers();
+	SDL_UpdateTexture(texture, NULL, (const void*)comp_framebuffer, screen_width * sizeof(unsigned int));
+	SDL_RenderCopy(renderer, texture, NULL, NULL);
+	SDL_RenderPresent(renderer);
+}
+
+void cat_init(void)
+{
+	SDL_Init(SDL_INIT_EVERYTHING);
+}
+
+void cat_fill(int layer, int visible, int x, int y, int w, int h, unsigned char r, unsigned char g, unsigned char b)
+{
+	int cy, cx;
+	for (cy = 0; cy < h; cy++)
+		for (cx = 0; cx < w; cx++)
+			cat_pixel(layer, visible, cx + x, cy + y, r, g, b);
+}
+
+/* TODO: cat bresenham */
+
+struct cat_event* cat_get_event(void)
+{
+	struct cat_event* out = malloc(sizeof(struct cat_event));
+	SDL_Event e;
+	(void)SDL_PollEvent(&e);
+	if (e.type == SDL_QUIT) out->type = QUIT;
+	else if (e.type == SDL_KEYDOWN)
+	{
+		out->type = KEYDOWN;
+		out->key = (e.key.keysym.sym);
+	}
+	else if (e.type == SDL_KEYUP)
+	{
+		out->type = KEYUP;
+		out->key = (e.key.keysym.sym);
+	}
+	else if (e.type == SDL_MOUSEMOTION)
+	{
+		out->type = MOUSEMOVE;
+		out->mousex = e.motion.x;
+		out->mousey = e.motion.y;
+	}
+	else if (e.type == SDL_MOUSEBUTTONDOWN)
+	{
+		out->type = MOUSEDOWN;
+		out->mouse_button = e.button.button;
+	}
+	else if (e.type == SDL_MOUSEBUTTONUP)
+	{
+		out->type = MOUSEUP;
+		out->mouse_button = e.button.button;
+	}
+	else return NULL;
+	return out;
+}

main.c

@@ -0,0 +1,54 @@
+#include "cat_api.h"
+#include <time.h>
+
+#define NS_PER_TICK 30000000
+
+void bye(void)
+{
+	printf("bye!\n");
+	exit(0);
+}
+
+void process_input(void)
+{
+	struct cat_event* e = cat_get_event();
+	if (e == NULL) return;
+	if (e->type == QUIT) bye();
+	else if (e->type == KEYDOWN) printf("keypress! %c\n", e->key);
+	else if (e->type == KEYUP) printf("key up! %c\n", e->key);
+	else if (e->type == MOUSEMOVE) printf("mouse move! (%d, %d)\n", e->mousex, e->mousey);
+	else if (e->type == MOUSEDOWN) printf("mouse down! %02x\n", e->mouse_button);
+	else if (e->type == MOUSEUP) printf("mouse up! %02x\n", e->mouse_button);
+}
+
+static long last_sec = 0;
+static long last_nsec = 0;
+
+void tick(void)
+{
+	/* run every N milliseconds... nanoseconds? idk */
+	struct timespec t;
+	clock_gettime(CLOCK_REALTIME, &t);
+	if (last_sec == 0) goto yes;
+	else if ((t.tv_sec - last_sec) > 0) goto yes;
+	else if ((t.tv_nsec - last_nsec) > NS_PER_TICK) goto yes;
+	else return;
+	yes:	last_sec = t.tv_sec;
+		last_nsec = t.tv_nsec;
+}
+
+void game_loop(void)
+{
+	process_input();
+	tick();
+	cat_render();
+}
+
+int main(int argc, char** argv)
+{
+	cat_init();
+	cat_create_window(1920, 1080);
+	cat_fill(0, 1, 0, 0, screen_width - 1, screen_height - 1, 132, 155, 132);
+	while (1) game_loop();
+	return 0;
+}

makefile

@@ -0,0 +1,6 @@
+all:
+	if ! [ -d bin ]; then mkdir bin; fi
+	cc -o bin/cfhfg main.c -lSDL2
+
+run: all
+	bin/cfhfg