Added rect draw api

Added some new maths types
Updated shaders to use new D_Rect structure
Added rect buffers to frames
Misc cleanup

code/draw/core.h

@@ -0,0 +1,85 @@
+#if !defined(LD_DRAW_CORE_H_)
+#define LD_DRAW_CORE_H_
+
+#define D_MAX_RECTS 1024
+
+typedef struct D_Image D_Image;
+struct D_Image {
+	Str8     name;
+	Vk_Image image;
+};
+
+typedef struct D_Rect D_Rect;
+struct D_Rect {
+	U32 texture;
+
+	U32  c[4]; // per-vertex colours
+	F32 uv[4];
+
+	F32 angle;
+	F32 x, y;
+	F32 w, h;
+
+	U32 p0, p1;
+};
+
+StaticAssert(sizeof(D_Rect) == 64);
+
+struct G_Camera;
+
+typedef struct D_Context D_Context;
+struct D_Context {
+	Vk_Buffer *rbo;
+
+	U32 n_pipelines;
+	Vk_Pipeline *pipelines;
+
+	U32 n_images;
+	D_Image *images;
+
+	U32 max_rects;
+	U32 n_rects;
+	D_Rect *rects;
+
+	U32 window_width;
+	U32 window_height;
+
+	struct G_Camera *camera;
+};
+
+typedef U32 D_RectFlags;
+enum D_RectFlags {
+	D_RECT_IGNORE_ASPECT     = (1 << 0), // by default only width is used as a "dimension"
+	D_RECT_PER_VERTEX_COLOUR = (1 << 1), // split colours per vertex
+};
+
+typedef struct D_RectOpts D_RectOpts;
+struct D_RectOpts {
+	D_RectFlags flags;
+
+	U32 texture;
+
+	R2f uv;
+	V2f p;
+
+	F32 angle;
+
+	union {
+		F32 w, h;
+		F32 scale, _h;
+		V2f dim;
+	};
+
+	union {
+		V4f c;
+		V4f vtxc[4];
+	};
+};
+
+function void D_Begin(D_Context *draw, Vk_Frame *frame, U32 max_rects);
+function void D_End(D_Context *draw, Vk_Frame *frame);
+
+function void _D_Rect(D_Context *draw, D_RectOpts *opts);
+#define D_Rect(draw, x, y, ...) _D_Rect(draw, &(D_RectOpts) { .p = V2F(x, y), .uv = R2F(V2F(0, 0), V2F(1, 1)), .scale = 1, .c = V4F(1, 1, 1, 1), ##__VA_ARGS__ })
+
+#endif  // LD_DRAW_CORE_H_