From cc71f7f9647ecec22926c3c0e848e0ee838e0308 Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Wed, 29 May 2019 12:58:59 -0700
Subject: [PATCH] GBA Video: Use interpolation not extrapolation for first few
scanlines (fixes #1431)
---
src/gba/renderers/gl.c | 61 +++++++++++++-----------------------------
1 file changed, 18 insertions(+), 43 deletions(-)
diff --git a/src/gba/renderers/gl.c b/src/gba/renderers/gl.c
index 56984b3bc..97acc8e02 100644
--- a/src/gba/renderers/gl.c
+++ b/src/gba/renderers/gl.c
@@ -214,7 +214,6 @@ static const char* const _interpolate =
"void loadAffine(int y, out ivec2 mat[4], out ivec2 aff[4]) {\n"
" int start = max(range.x, y - 3);\n"
-
" mat[0] = transform[start + 0].xy;\n"
" aff[0] = transform[start + 0].zw;\n"
" mat[1] = transform[start + 1].xy;\n"
@@ -223,45 +222,6 @@ static const char* const _interpolate =
" aff[2] = transform[start + 2].zw;\n"
" mat[3] = transform[start + 3].xy;\n"
" aff[3] = transform[start + 3].zw;\n"
-
- " if (y - 3 < range.x) {\n"
- " ivec2 tempMat[3];\n"
- " ivec2 tempAff[3];\n"
- " tempMat[0] = ivec2(interpolate(mat, -0.75));\n"
- " tempMat[1] = ivec2(interpolate(mat, -0.5));\n"
- " tempMat[2] = ivec2(interpolate(mat, -0.25));\n"
- " tempAff[0] = ivec2(interpolate(aff, -0.75));\n"
- " tempAff[1] = ivec2(interpolate(aff, -0.5));\n"
- " tempAff[2] = ivec2(interpolate(aff, -0.25));\n"
- " if (range.x == y) {\n"
- " mat[3] = mat[0];\n"
- " mat[2] = tempMat[2];\n"
- " mat[1] = tempMat[1];\n"
- " mat[0] = tempMat[0];\n"
- " aff[3] = aff[0];\n"
- " aff[2] = tempAff[2];\n"
- " aff[1] = tempAff[1];\n"
- " aff[0] = tempAff[0];\n"
- " } else if (range.x == y - 1) {\n"
- " mat[3] = mat[1];\n"
- " mat[2] = mat[0];\n"
- " mat[1] = tempMat[2];\n"
- " mat[0] = tempMat[1];\n"
- " aff[3] = aff[1];\n"
- " aff[2] = aff[0];\n"
- " aff[1] = tempAff[2];\n"
- " aff[0] = tempAff[1];\n"
- " } else if (range.x == y - 2) {\n"
- " mat[3] = mat[2];\n"
- " mat[2] = mat[1];\n"
- " mat[1] = mat[0];\n"
- " mat[0] = tempMat[0];\n"
- " aff[3] = aff[2];\n"
- " aff[2] = aff[1];\n"
- " aff[1] = aff[0];\n"
- " aff[0] = tempAff[0];\n"
- " }\n"
- " }\n"
"}\n";
static const char* const _renderMode2 =
@@ -311,7 +271,12 @@ static const char* const _renderMode2 =
" }\n"
" loadAffine(int(incoord.y), mat, offset);\n"
" float y = fract(incoord.y);\n"
- " float lin = 0.75 + y * 0.25;\n"
+ " float start = 0.75;\n"
+ " if (int(incoord.y) - range.x < 4) {\n"
+ " y = incoord.y - float(range.x);\n"
+ " start = 0.;\n"
+ " }\n"
+ " float lin = start + y * 0.25;\n"
" vec2 mixedTransform = interpolate(mat, lin);\n"
" vec2 mixedOffset = interpolate(offset, lin);\n"
" color = fetchTile(ivec2(mixedTransform * incoord.x + mixedOffset));\n"
@@ -359,7 +324,12 @@ static const char* const _renderMode35 =
" }\n"
" loadAffine(int(incoord.y), mat, offset);\n"
" float y = fract(incoord.y);\n"
- " float lin = 0.75 + y * 0.25;\n"
+ " float start = 0.75;\n"
+ " if (int(incoord.y) - range.x < 4) {\n"
+ " y = incoord.y - float(range.x);\n"
+ " start = 0.;\n"
+ " }\n"
+ " float lin = start + y * 0.25;\n"
" vec2 mixedTransform = interpolate(mat, lin);\n"
" vec2 mixedOffset = interpolate(offset, lin);\n"
" ivec2 coord = ivec2(mixedTransform * incoord.x + mixedOffset);\n"
@@ -419,7 +389,12 @@ static const char* const _renderMode4 =
" }\n"
" loadAffine(int(incoord.y), mat, offset);\n"
" float y = fract(incoord.y);\n"
- " float lin = 0.75 + y * 0.25;\n"
+ " float start = 0.75;\n"
+ " if (int(incoord.y) - range.x < 4) {\n"
+ " y = incoord.y - float(range.x);\n"
+ " start = 0.;\n"
+ " }\n"
+ " float lin = start + y * 0.25;\n"
" vec2 mixedTransform = interpolate(mat, lin);\n"
" vec2 mixedOffset = interpolate(offset, lin);\n"
" ivec2 coord = ivec2(mixedTransform * incoord.x + mixedOffset);\n"