Start implementing drawing order

include/rasteriser/rasteriser.h

@@ -31,7 +31,8 @@ MAKE_LIST_TYPE(scene_triangle_t);
 
 typedef enum {
   RASTERISER_RENDER_WIREFRAME,
-  RASTERISER_RENDER_SOLID,
+  RASTERISER_RENDER_FILLED,
+  RASTERISER_RENDER_SHADED,
 } render_type_t;
 
 typedef struct {
@@ -46,6 +47,9 @@ typedef struct {
   f32 h0;
   f32 h1;
   f32 h2;
+  f32 z0;
+  f32 z1;
+  f32 z2;
   colour_t colour;
 } triangle_t;