From 0ea3df5de9583b4201a0c3e664701824f90dc32b Mon Sep 17 00:00:00 2001
From: Nico de Poel <ndepoel@gmail.com>
Date: Fri, 17 Feb 2023 11:54:52 +0100
Subject: [PATCH] Selection between textured/untextured face drawing functions
 moved one abstraction level higher. This eliminates redundant texture window
 swaps when drawing untextured, and is a bit faster overall as well.

---
 world.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/world.c b/world.c
index cd7fb0f..013ed1b 100644
--- a/world.c
+++ b/world.c
@@ -195,9 +195,19 @@ static void world_drawface_textured(const world_t *world, const ps1bsp_face_t *f
     }
 }
 
-static void (*world_drawface)(const world_t*, const ps1bsp_face_t*, u_long *ot) = &world_drawface_fast;
+static void world_drawFacesLit(const world_t *world, const ps1bsp_face_t *firstFace)
+{
+    for (const ps1bsp_face_t *face = firstFace; face != NULL; face = face->nextFace)
+    {
+        // Early primitive buffer check
+        if (!mem_checkprim(sizeof(POLY_G4), face->totalPrimitives))
+            break;
 
-static void world_drawFaces(const world_t *world, const ps1bsp_face_t *firstFace)
+        world_drawface_lit(world, face, curOT);
+    }
+}
+
+static void world_drawFacesTextured(const world_t *world, const ps1bsp_face_t *firstFace)
 {
     // Make sure we set the texture window back to default after drawing the world
     unsigned int prevTexWin = 0xe2000000;
@@ -211,8 +221,8 @@ static void world_drawFaces(const world_t *world, const ps1bsp_face_t *firstFace
         if (!mem_checkprim(sizeof(POLY_GT4) + sizeof(DR_TWIN), face->totalPrimitives))
             break;
 
-        // Texture window commands needs to be placed *after* the draw commands, because the commands are executed in reverse order
         // Set the texture window for the previous face if it changes in-between faces
+        // Texture window commands needs to be placed *after* the draw commands, because the commands are executed in reverse order
         const ps1bsp_texture_t *texture = &world->textures[face->textureId];
         if (prevTexWin != texture->twin)
         {
@@ -220,13 +230,15 @@ static void world_drawFaces(const world_t *world, const ps1bsp_face_t *firstFace
             prevTexWin = texture->twin;
         }
 
-        world_drawface(world, face, curOT);
+        world_drawface_textured(world, face, curOT);
     }
 
     // Set the texture window for the first face to be drawn
     draw_texwindow(prevTexWin, curOT);
 }
 
+static void (*world_drawFaces)(const world_t *world, const ps1bsp_face_t *firstFace) = &world_drawFacesTextured;
+
 // Simplified BSP subtree traversal specifically for sorting faces of brush models.
 // This skips the frustum culling and PVS culling stages, as this will have already been done on the leafs containing the model.
 static ps1bsp_face_t *world_sortModelFaces(const world_t* world, const ps1bsp_model_t* model, u_long frameNum, ps1bsp_face_t **lastFace)
@@ -493,9 +505,9 @@ void world_draw(const world_t *world)
     ps1bsp_face_t *firstFace = world_sortFaces(world, firstLeaf);
 
     if (enableTexturing)
-        world_drawface = &world_drawface_textured;
+        world_drawFaces = &world_drawFacesTextured;
     else
-        world_drawface = &world_drawface_lit;
+        world_drawFaces = &world_drawFacesLit;
 
     world_drawFaces(world, firstFace);
 }