From bc0bf4d3d283bdb979bc0daf2a745d894243c6ce Mon Sep 17 00:00:00 2001
From: GPUCode <47210458+GPUCode@users.noreply.github.com>
Date: Thu, 17 Aug 2023 23:16:28 +0300
Subject: [PATCH] (gl/vk)_shader_gen: Use floor instead of int cast (#6885)

---
 src/video_core/renderer_opengl/gl_shader_gen.cpp     |  4 ++--
 src/video_core/renderer_vulkan/vk_shader_gen.cpp     |  4 ++--
 src/video_core/renderer_vulkan/vk_shader_gen_spv.cpp | 10 ++++++----
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/src/video_core/renderer_opengl/gl_shader_gen.cpp b/src/video_core/renderer_opengl/gl_shader_gen.cpp
index 128137d52..733453158 100644
--- a/src/video_core/renderer_opengl/gl_shader_gen.cpp
+++ b/src/video_core/renderer_opengl/gl_shader_gen.cpp
@@ -1246,13 +1246,13 @@ float LookupLightingLUT(int lut_index, int index, float delta) {
 }
 
 float LookupLightingLUTUnsigned(int lut_index, float pos) {
-    int index = clamp(int(pos * 256.0), 0, 255);
+    int index = int(clamp(floor(pos * 256.0), 0.f, 255.f));
     float delta = pos * 256.0 - float(index);
     return LookupLightingLUT(lut_index, index, delta);
 }
 
 float LookupLightingLUTSigned(int lut_index, float pos) {
-    int index = clamp(int(pos * 128.0), -128, 127);
+    int index = int(clamp(floor(pos * 128.0), -128.f, 127.f));
     float delta = pos * 128.0 - float(index);
     if (index < 0) index += 256;
     return LookupLightingLUT(lut_index, index, delta);
diff --git a/src/video_core/renderer_vulkan/vk_shader_gen.cpp b/src/video_core/renderer_vulkan/vk_shader_gen.cpp
index 555b17b5b..8ad0eb4d8 100644
--- a/src/video_core/renderer_vulkan/vk_shader_gen.cpp
+++ b/src/video_core/renderer_vulkan/vk_shader_gen.cpp
@@ -1247,13 +1247,13 @@ float LookupLightingLUT(int lut_index, int index, float delta) {
 }
 
 float LookupLightingLUTUnsigned(int lut_index, float pos) {
-    int index = clamp(int(pos * 256.0), 0, 255);
+    int index = int(clamp(floor(pos * 256.0), 0.f, 255.f));
     float delta = pos * 256.0 - float(index);
     return LookupLightingLUT(lut_index, index, delta);
 }
 
 float LookupLightingLUTSigned(int lut_index, float pos) {
-    int index = clamp(int(pos * 128.0), -128, 127);
+    int index = int(clamp(floor(pos * 128.0), -128.f, 127.f));
     float delta = pos * 128.0 - float(index);
     if (index < 0) index += 256;
     return LookupLightingLUT(lut_index, index, delta);
diff --git a/src/video_core/renderer_vulkan/vk_shader_gen_spv.cpp b/src/video_core/renderer_vulkan/vk_shader_gen_spv.cpp
index 0b9647e3f..cf26a927f 100644
--- a/src/video_core/renderer_vulkan/vk_shader_gen_spv.cpp
+++ b/src/video_core/renderer_vulkan/vk_shader_gen_spv.cpp
@@ -291,16 +291,18 @@ void FragmentModule::WriteLighting() {
     }
 
     const auto lookup_lighting_lut_unsigned = [this](Id lut_index, Id pos) -> Id {
-        const Id pos_int{OpConvertFToS(i32_id, OpFMul(f32_id, pos, ConstF32(256.f)))};
-        const Id index{OpSClamp(i32_id, pos_int, ConstS32(0), ConstS32(255))};
+        const Id pos_floor{OpFloor(f32_id, OpFMul(f32_id, pos, ConstF32(256.f)))};
+        const Id index_float{OpFClamp(f32_id, pos_floor, ConstF32(0.f), ConstF32(255.f))};
+        const Id index{OpConvertFToS(i32_id, index_float)};
         const Id neg_index{OpFNegate(f32_id, OpConvertSToF(f32_id, index))};
         const Id delta{OpFma(f32_id, pos, ConstF32(256.f), neg_index)};
         return LookupLightingLUT(lut_index, index, delta);
     };
 
     const auto lookup_lighting_lut_signed = [this](Id lut_index, Id pos) -> Id {
-        const Id pos_int{OpConvertFToS(i32_id, OpFMul(f32_id, pos, ConstF32(128.f)))};
-        const Id index{OpSClamp(i32_id, pos_int, ConstS32(-128), ConstS32(127))};
+        const Id pos_floor{OpFloor(f32_id, OpFMul(f32_id, pos, ConstF32(128.f)))};
+        const Id index_float{OpFClamp(f32_id, pos_floor, ConstF32(-128.f), ConstF32(127.f))};
+        const Id index{OpConvertFToS(i32_id, index_float)};
         const Id neg_index{OpFNegate(f32_id, OpConvertSToF(f32_id, index))};
         const Id delta{OpFma(f32_id, pos, ConstF32(128.f), neg_index)};
         const Id increment{