From e71f6aa80a4d0c01f2ce71850103f9c20bed0bfc Mon Sep 17 00:00:00 2001
From: Connor McLaughlin <stenzek@gmail.com>
Date: Sat, 26 Dec 2020 15:53:19 +1000
Subject: [PATCH] GPU/HW: Improve round-trip accuracy of RGBA5551->RGBA8
Fixes smudging in some games with true colour rendering enabled.
---
src/core/gpu_hw_shadergen.cpp | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)
diff --git a/src/core/gpu_hw_shadergen.cpp b/src/core/gpu_hw_shadergen.cpp
index 808191e5e..7152ef118 100644
--- a/src/core/gpu_hw_shadergen.cpp
+++ b/src/core/gpu_hw_shadergen.cpp
@@ -47,9 +47,9 @@ uint fixYCoord(uint y)
uint RGBA8ToRGBA5551(float4 v)
{
- uint r = uint(roundEven(v.r * 255.0)) >> 3;
- uint g = uint(roundEven(v.g * 255.0)) >> 3;
- uint b = uint(roundEven(v.b * 255.0)) >> 3;
+ uint r = uint(roundEven(v.r * 31.0));
+ uint g = uint(roundEven(v.g * 31.0));
+ uint b = uint(roundEven(v.b * 31.0));
uint a = (v.a != 0.0) ? 1u : 0u;
return (r) | (g << 5) | (b << 10) | (a << 15);
}
@@ -61,12 +61,7 @@ float4 RGBA5551ToRGBA8(uint v)
uint b = ((v >> 10) & 31u);
uint a = ((v >> 15) & 1u);
- // repeat lower bits
- r = (r << 3) | (r & 7u);
- g = (g << 3) | (g & 7u);
- b = (b << 3) | (b & 7u);
-
- return float4(float(r) / 255.0, float(g) / 255.0, float(b) / 255.0, float(a));
+ return float4(float(r) / 31.0, float(g) / 31.0, float(b) / 31.0, float(a));
}
)";
}