1 files changed, 98 insertions, 0 deletions
diff --git a/src/video_core/transform_feedback.cpp b/src/video_core/transform_feedback.cpp
new file mode 100644
index 000000000..db52fff93
--- /dev/null
+++ b/src/video_core/transform_feedback.cpp
@@ -0,0 +1,98 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <algorithm>
+#include <array>
+#include <vector>
+
+#include "common/alignment.h"
+#include "common/assert.h"
+#include "shader_recompiler/shader_info.h"
+#include "video_core/transform_feedback.h"
+
+namespace VideoCommon {
+
+std::vector<Shader::TransformFeedbackVarying> MakeTransformFeedbackVaryings(
+    const TransformFeedbackState& state) {
+    static constexpr std::array VECTORS{
+        28,  // gl_Position
+        32,  // Generic 0
+        36,  // Generic 1
+        40,  // Generic 2
+        44,  // Generic 3
+        48,  // Generic 4
+        52,  // Generic 5
+        56,  // Generic 6
+        60,  // Generic 7
+        64,  // Generic 8
+        68,  // Generic 9
+        72,  // Generic 10
+        76,  // Generic 11
+        80,  // Generic 12
+        84,  // Generic 13
+        88,  // Generic 14
+        92,  // Generic 15
+        96,  // Generic 16
+        100, // Generic 17
+        104, // Generic 18
+        108, // Generic 19
+        112, // Generic 20
+        116, // Generic 21
+        120, // Generic 22
+        124, // Generic 23
+        128, // Generic 24
+        132, // Generic 25
+        136, // Generic 26
+        140, // Generic 27
+        144, // Generic 28
+        148, // Generic 29
+        152, // Generic 30
+        156, // Generic 31
+        160, // gl_FrontColor
+        164, // gl_FrontSecondaryColor
+        160, // gl_BackColor
+        164, // gl_BackSecondaryColor
+        192, // gl_TexCoord[0]
+        196, // gl_TexCoord[1]
+        200, // gl_TexCoord[2]
+        204, // gl_TexCoord[3]
+        208, // gl_TexCoord[4]
+        212, // gl_TexCoord[5]
+        216, // gl_TexCoord[6]
+        220, // gl_TexCoord[7]
+    };
+    std::vector<Shader::TransformFeedbackVarying> xfb(256);
+    for (size_t buffer = 0; buffer < state.layouts.size(); ++buffer) {
+        const auto& locations = state.varyings[buffer];
+        const auto& layout = state.layouts[buffer];
+        const u32 varying_count = layout.varying_count;
+        u32 highest = 0;
+        for (u32 offset = 0; offset < varying_count; ++offset) {
+            const u32 base_offset = offset;
+            const u8 location = locations[offset];
+
+            Shader::TransformFeedbackVarying varying{
+                .buffer = layout.stream,
+                .stride = layout.stride,
+                .offset = offset * 4,
+                .components = 1,
+            };
+            if (std::ranges::find(VECTORS, Common::AlignDown(location, 4)) != VECTORS.end()) {
+                UNIMPLEMENTED_IF_MSG(location % 4 != 0, "Unaligned TFB");
+
+                const u8 base_index = location / 4;
+                while (offset + 1 < varying_count && base_index == locations[offset + 1] / 4) {
+                    ++offset;
+                    ++varying.components;
+                }
+            }
+            xfb[location] = varying;
+            highest = std::max(highest, (base_offset + varying.components) * 4);
+        }
+        UNIMPLEMENTED_IF(highest != layout.stride);
+    }
+    return xfb;
+}
+
+} // namespace VideoCommon