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authorGravatar Yuri Kunde Schlesner <yuriks@yuriks.net>2015-07-21 01:24:27 -0300
committerGravatar Yuri Kunde Schlesner <yuriks@yuriks.net>2015-07-23 16:51:24 -0300
commit4e092022267e4f232429013653ba1bd4ac8b0a05 (patch)
parentcea45af64d30e144f71dc98125755758fa7302a0 (diff)
VideoCore: Saturate vertex colors before interpolating
During testing, it was discovered that hardware does not interpolate colors output by the vertex shader as-is. Rather, it drops the sign and saturates the value to 1.0. This is done before interpolation, such that (e.g.) interpolating outputs 1.5 and -0.5 is equivalent to as if the shader had output the values 1.0 and 0.5 instead, with the interpolated value never crossing 0.0. This change has been tested against hardware.
1 files changed, 6 insertions, 0 deletions
diff --git a/src/video_core/vertex_shader.cpp b/src/video_core/vertex_shader.cpp
index b7750380..ff114fc3 100644
--- a/src/video_core/vertex_shader.cpp
+++ b/src/video_core/vertex_shader.cpp
@@ -610,6 +610,12 @@ OutputVertex RunShader(const InputVertex& input, int num_attributes, const Regs:
+ // The hardware takes the absolute and saturates vertex colors like this, *before* doing interpolation
+ for (int i = 0; i < 4; ++i) {
+ ret.color[i] = float24::FromFloat32(
+ std::fmin(std::fabs(ret.color[i].ToFloat32()), 1.0f));
+ }
LOG_TRACE(Render_Software, "Output vertex: pos (%.2f, %.2f, %.2f, %.2f), col(%.2f, %.2f, %.2f, %.2f), tc0(%.2f, %.2f)",
ret.pos.x.ToFloat32(), ret.pos.y.ToFloat32(), ret.pos.z.ToFloat32(), ret.pos.w.ToFloat32(),
ret.color.x.ToFloat32(), ret.color.y.ToFloat32(), ret.color.z.ToFloat32(), ret.color.w.ToFloat32(),