Implement shaders (#1)

Reviewed-on: #1

	* Start implementing shaders and move vector code to dedicated files
	* Extract shader into its own header
	* Ensure pixel coordinates are within bounds
	* Refactor shader code and implement fragment shaders
	* Create shaders
	* Reorganise code
Co-authored-by: Abdelrahman <said.abdelrahman89@gmail.com>
Co-committed-by: Abdelrahman <said.abdelrahman89@gmail.com>

src/img/img.h

@@ -0,0 +1,43 @@
+#ifndef IMG_H
+#define IMG_H
+
+#include "aliases.h"
+#include "mem_arena.h"
+#include <stdbool.h>
+
+#define BUF_TYPE(TYPE, NAME)                                                   \
+  typedef struct NAME {                                                        \
+    u64 width;                                                                 \
+    u64 height;                                                                \
+    TYPE *buf;                                                                 \
+  } NAME
+
+typedef struct colour Colour;
+struct colour {
+  u8 r;
+  u8 g;
+  u8 b;
+  u8 a;
+};
+
+BUF_TYPE(void, Buffer);
+BUF_TYPE(Colour, Image);
+BUF_TYPE(f32, Depth);
+
+#define init_buffer(ARENA, BUF)                                                \
+  _init_buffer(ARENA, (Buffer *)BUF, sizeof(*((BUF)->buf)))
+#define get_pixel(TYPE, BUF, X, Y)                                             \
+  (*((TYPE *)(_get_pixel((Buffer *)BUF, X, Y, sizeof(*((BUF)->buf))))))
+#define set_pixel(BUF, X, Y, VAL_PTR)                                          \
+  _set_pixel((Buffer *)BUF, X, Y, VAL_PTR, sizeof(*((BUF)->buf)))
+#define clear_buffer(BUF, VAL_PTR)                                             \
+  _clear_buffer((Buffer *)BUF, VAL_PTR, sizeof(*((BUF)->buf)))
+
+bool _init_buffer(Arena *arena, Buffer *buffer, u64 base_size);
+u8 *_get_pixel(Buffer *buffer, u64 x, u64 y, u64 base_size);
+void _set_pixel(Buffer *buffer, u64 x, u64 y, void *value, u64 base_size);
+void _clear_buffer(Buffer *buffer, void *value, u64 base_size);
+void draw_line(Image *img, u64 x0, u64 y0, u64 x1, u64 y1, Colour colour);
+void save_image(const Image *img, const char *filename);
+
+#endif // IMG_H