From eb3de1b6244bab588c1506a57693e1a7db8efded Mon Sep 17 00:00:00 2001
From: Nico de Poel <ndepoel@gmail.com>
Date: Tue, 14 Feb 2023 13:18:49 +0100
Subject: [PATCH] Pack repeatable textures first, followed by other textures in
 the remaining space. This is actually producing more efficient textures
 atlases. The hell.

---
 texture.cpp | 42 ++++++++++++++++++++++++++++++++++++------
 1 file changed, 36 insertions(+), 6 deletions(-)

diff --git a/texture.cpp b/texture.cpp
index e6ab4ef..d0fe71b 100644
--- a/texture.cpp
+++ b/texture.cpp
@@ -253,12 +253,11 @@ bool process_textures(const world_t* world, TextureList& outTextures)
 	outTim.clutYoffs = 0;
 	generate_clut(palette, &outTim);
 
-	const auto max_bin = rectpack2D::rect_wh(1024, 256);	// 8-bit textures take up half the horizontal space so this is 512x256 in practice, or a quarter of the PS1's VRAM allocation.
+	auto max_bin = rectpack2D::rect_wh(1024, 256);	// 8-bit textures take up half the horizontal space so this is 512x256 in practice, or a quarter of the PS1's VRAM allocation.
 	
 	printf("Finding best texture packing...\n");
 
-	std::map<int, miptex_t*> textures;
-	std::vector<rect_type> rectangles;
+	std::map<int, miptex_t*> textures, repeatables;
 
 	// Try some texture packing and see if we fit inside the PS1's VRAM
 	for (int texNum = 0; texNum < world->mipheader.numtex; ++texNum)
@@ -269,10 +268,41 @@ bool process_textures(const world_t* world, TextureList& outTextures)
 
 		//printf("Texture %d (%dx%d): %.16s\n", texNum, miptex->width, miptex->height, miptex->name);
 
-		textures[texNum] = miptex;
+		if (texture_isRepeatable(miptex))
+			repeatables[texNum] = miptex;
+		else
+			textures[texNum] = miptex;
 	}
 
-	const auto result_size = pack_textures(textures, max_bin, rectangles);
+	// Pack the repeatable textures first, so that they get placed at predictable locations
+	// rectpack2D is set up to pack larger textures first, so this actually works out with power-of-two textures
+	std::vector<rect_type> rRects;
+	const auto rSize = pack_textures(repeatables, max_bin, rRects);
+
+	max_bin.w -= rSize.w;
+
+	// Pack the remaining textures into the remaining space
+	std::vector<rect_type> tRects;
+	const auto tSize = pack_textures(textures, max_bin, tRects);
+
+	auto result_size = rectpack2D::rect_wh(rSize.w + tSize.w, max(rSize.h, tSize.h));
+
+	// Collect all of the texture rectangles back into a single in-order list again
+	std::vector<rect_type> rectangles;
+	auto rIter = rRects.begin();
+	auto tIter = tRects.begin();
+	for (int texNum = 0; texNum < world->mipheader.numtex; ++texNum)
+	{
+		if (repeatables.find(texNum) != repeatables.end())
+		{
+			rectangles.push_back(*rIter++);
+			continue;
+		}
+		
+		auto rect = *tIter++;
+		rect.x += rSize.w;
+		rectangles.push_back(rect);
+	}
 
 	printf("%d textures. Packed texture atlas size: %d x %d\n", world->mipheader.numtex, result_size.w, result_size.h);
 	
@@ -320,7 +350,7 @@ bool process_textures(const world_t* world, TextureList& outTextures)
 				tex.ps1tex.tpage = getTPage(outTim.format, 0, x, y);
 				tex.uoffs = (u_char)((x % 64) << (2 - outTim.format));
 				tex.voffs = (u_char)(y & 0xFF);
-				tex.ps1tex.twin = getTexWindow(tex.uoffs, tex.voffs, tex.w, tex.h);	// TODO: figure out the right offsets that are multiples of w and h
+				tex.ps1tex.twin = getTexWindow(tex.uoffs, tex.voffs, tex.w, tex.h);	// TODO: figure out the right offsets that are multiples of w and h; NOTE: if uoffs has to >> 1, then w probably has to as well
 			}
 		}