Commentary and TODOs

draw.h

@@ -384,6 +384,8 @@ typedef struct _TMPVERT
     blit32(&(dst).vz, &(v)->vz); \
     blit16(&(dst).u, &(pv)->u);
 
+// Vertex interpolation using GTE macros
+// Interpolates XYZ, RGB and UV separately
 #define lerpVert(dst, src0, src1) \
     gte_ld_intpol_sv1(&(src0).vx); \
     gte_ld_intpol_sv0(&(src1).vx); \
@@ -398,6 +400,9 @@ typedef struct _TMPVERT
     gte_intpl(); \
     gte_stbv(&(dst).u);
 
+// Vertex interpolation using pure assembly
+// Combines UV and R into a single vector, thus requiring only two interpolates
+// Outputs the interpolated light value directly to the R, G and B fields of dst
 #define lerpVert2(dst, src0, src1) __asm__ volatile ( \
 	"lh	$12, 0( %1 );"		\
 	"lh	$13, 2( %1 );"		\
@@ -467,7 +472,6 @@ static INLINE void draw_quadstrip_tess2(const ps1bsp_vertex_t *vertices, const p
     gte_lddp(ONE >> 1);
 
     // Normally a quad strip would have (N-2)/2 quads, but we might end up with a sole triangle at the end which will be drawn as a collapsed quad
-    // NOTE: testing has shown that the PS1 is faster just rendering quads and accepting the odd collapsed quad, rather than being clever with pointer comparisons and drawing a single triangle at the end.
     u_char numQuads = (numVerts - 1) >> 1;
     for (u_char quadIdx = 0; quadIdx < numQuads; ++quadIdx)
     {
@@ -492,6 +496,8 @@ static INLINE void draw_quadstrip_tess2(const ps1bsp_vertex_t *vertices, const p
         copyVertFast(tmp[8], pv3, v3);
 
         // TODO Optimization: start loading vertices into GTE as soon as we're done with them
+        // TODO Even better: make lerpVert also push the resulting XYZ straight to the C2_VXYZn data registers
+        // NOTE: could separate XYZ lerping from UVL lerping, as XYZ needs to be transformed whereas UVL doesn't. UVL lerping might also be faster on CPU.
         lerpVert2(&tmp[1], &tmp[0], &tmp[2]);
         lerpVert2(&tmp[5], &tmp[2], &tmp[8]);    // After this, 0 1 2 are ready for GTE
         lerpVert2(&tmp[3], &tmp[0], &tmp[6]);
@@ -517,7 +523,7 @@ static INLINE void draw_quadstrip_tess2(const ps1bsp_vertex_t *vertices, const p
         gte_stsxy1(&tmp[7].vx);
         gte_stsxy2(&tmp[8].vx);
 
-        // TODO Optimization: interperse quad building instructions while waiting on GTE store/load delays
+        // TODO Optimization: intersperse quad building instructions while waiting on GTE store/load delays
 
         // Draw the first quad
         p0 = (POLY_GT4*)mem_prim(sizeof(POLY_GT4));

world.c

@@ -82,6 +82,7 @@ static INLINE short world_cull_backface(const world_t *world, const ps1bsp_face_
     // Check if the face is behind the camera
     // NOTE: disabling the behind-the-camera check does *not* actually solve the problem of polygons disappearing when too close to the camera!
     // This means that the GPU probably already clips polygons that stretch too far outside the drawing area. Tessellation should solve this.
+    // UPDATE: tessellation does solve this, to an extent. However we must also make sure not to discard faces partially inside the frustum, and force tessellation on those.
     int camDot = m_dot12(&cam_vec, &cam_dir);
     if (camDot < 0)
         return 0;
@@ -322,6 +323,12 @@ static void world_sortModels(const world_t *world)
         ps1bsp_model_t* model = (ps1bsp_model_t*)&world->models[modelIdx];
         ps1bsp_leaf_t* leaf = (ps1bsp_leaf_t*)model->currentLeaf;
 
+        // TODO: skip clip brush-only models (clip and trigger textures)
+        // TODO: frustum culling (may be more expensive than it's worth)
+        // TODO: instead of leaf, refer to a node, i.e. the first one that splits the model's bounding box/sphere (R_FindTopnode in Q2 code)
+        // Q2 distinguishes between models that fall entirely in one leaf (i.e. small ones) and ones split by a node; the latter is clipped by R_DrawSolidClippedSubmodelPolygons
+        // Could probably traverse BSP tree from top node and divide up model faces per leaf, insert them as the leaf faces are sorted
+
         // Update the model's current leaf. This only needs to be done when the model moves.
         if (leaf == NULL)
         {