Fix indirect textures when format is not ITF_8

1 files changed, 20 insertions, 15 deletions

diff --git a/Source/Core/VideoCommon/PixelShaderGen.cpp b/Source/Core/VideoCommon/PixelShaderGen.cpp
index ed3733d035..4413c6d9b6 100644
--- a/Source/Core/VideoCommon/PixelShaderGen.cpp
+++ b/Source/Core/VideoCommon/PixelShaderGen.cpp
@@ -1006,17 +1006,22 @@ static void WriteStage(ShaderCode& out, const pixel_shader_uid_data* uid_data, i
           "z",
       };
 
-      // 0b11111000, 0b11100000, 0b11110000, 0b11111000
-      static constexpr std::array<const char*, 4> tev_ind_alpha_mask{
-          "248",
-          "224",
-          "240",
-          "248",
+      // According to libogc, the bump alpha value is 5 bits, and comes from the bottom bits of the
+      // component byte, except in the case of ITF_8, which presumably uses the top bits with a
+      // mask.
+      // https://github.com/devkitPro/libogc/blob/bd24a9b3f59502f9b30d6bac0ae35fc485045f78/gc/ogc/gx.h#L3038-L3041
+      // https://github.com/devkitPro/libogc/blob/bd24a9b3f59502f9b30d6bac0ae35fc485045f78/gc/ogc/gx.h#L790-L800
+
+      static constexpr std::array<char, 4> tev_ind_alpha_shift{
+          '0',  // ITF_8: 0bXXXXXYYY -> 0bXXXXX000? No shift?
+          '5',  // ITF_5: 0bIIIIIAAA -> 0bAAA00000, shift of 5
+          '4',  // ITF_4: 0bIIIIAAAA -> 0bAAAA0000, shift of 4
+          '3',  // ITF_3: 0bIIIAAAAA -> 0bAAAAA000, shift of 3
       };
 
-      out.Write("alphabump = iindtex{}.{} & {};\n", tevind.bt.Value(),
+      out.Write("alphabump = (iindtex{}.{} << {}) & 248;\n", tevind.bt.Value(),
                 tev_ind_alpha_sel[u32(tevind.bs.Value())],
-                tev_ind_alpha_mask[u32(tevind.fmt.Value())]);
+                tev_ind_alpha_shift[u32(tevind.fmt.Value())]);
     }
     else
     {
@@ -1026,14 +1031,14 @@ static void WriteStage(ShaderCode& out, const pixel_shader_uid_data* uid_data, i
     if (has_ind_stage && tevind.matrix_index != IndMtxIndex::Off)
     {
       // format
-      static constexpr std::array<const char*, 4> tev_ind_fmt_mask{
-          "255",
-          "31",
-          "15",
-          "7",
+      static constexpr std::array<char, 4> tev_ind_fmt_shift{
+          '0',  // ITF_8: 0bXXXXXXXX -> 0bXXXXXXXX, no shift
+          '3',  // ITF_5: 0bIIIIIAAA -> 0b000IIIII, shift of 3
+          '4',  // ITF_4: 0bIIIIAAAA -> 0b0000IIII, shift of 4
+          '5',  // ITF_3: 0bIIIAAAAA -> 0b00000III, shift of 5
       };
-      out.Write("\tint3 iindtevcrd{} = iindtex{} & {};\n", n, tevind.bt.Value(),
-                tev_ind_fmt_mask[u32(tevind.fmt.Value())]);
+      out.Write("\tint3 iindtevcrd{} = iindtex{} >> {};\n", n, tevind.bt.Value(),
+                tev_ind_fmt_shift[u32(tevind.fmt.Value())]);
 
       // bias - TODO: Check if this needs to be this complicated...
       // indexed by bias