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-rw-r--r--src/video_core/host_shaders/CMakeLists.txt1
-rw-r--r--src/video_core/host_shaders/opengl_copy_bc4.comp70
2 files changed, 71 insertions, 0 deletions
diff --git a/src/video_core/host_shaders/CMakeLists.txt b/src/video_core/host_shaders/CMakeLists.txt
index 5770c4761..338bf9eec 100644
--- a/src/video_core/host_shaders/CMakeLists.txt
+++ b/src/video_core/host_shaders/CMakeLists.txt
@@ -2,6 +2,7 @@ set(SHADER_FILES
block_linear_unswizzle_2d.comp
block_linear_unswizzle_3d.comp
full_screen_triangle.vert
+ opengl_copy_bc4.comp
opengl_present.frag
opengl_present.vert
pitch_unswizzle.comp
diff --git a/src/video_core/host_shaders/opengl_copy_bc4.comp b/src/video_core/host_shaders/opengl_copy_bc4.comp
new file mode 100644
index 000000000..7b8e20fbe
--- /dev/null
+++ b/src/video_core/host_shaders/opengl_copy_bc4.comp
@@ -0,0 +1,70 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#version 430 core
+#extension GL_ARB_gpu_shader_int64 : require
+
+layout (local_size_x = 4, local_size_y = 4) in;
+
+layout(binding = 0, rg32ui) readonly uniform uimage3D bc4_input;
+layout(binding = 1, rgba8ui) writeonly uniform uimage3D bc4_output;
+
+layout(location = 0) uniform uvec3 src_offset;
+layout(location = 1) uniform uvec3 dst_offset;
+
+// https://www.khronos.org/registry/OpenGL/extensions/ARB/ARB_texture_compression_rgtc.txt
+uint DecompressBlock(uint64_t bits, uvec2 coord) {
+ const uint code_offset = 16 + 3 * (4 * coord.y + coord.x);
+ const uint code = uint(bits >> code_offset) & 7;
+ const uint red0 = uint(bits >> 0) & 0xff;
+ const uint red1 = uint(bits >> 8) & 0xff;
+ if (red0 > red1) {
+ switch (code) {
+ case 0:
+ return red0;
+ case 1:
+ return red1;
+ case 2:
+ return (6 * red0 + 1 * red1) / 7;
+ case 3:
+ return (5 * red0 + 2 * red1) / 7;
+ case 4:
+ return (4 * red0 + 3 * red1) / 7;
+ case 5:
+ return (3 * red0 + 4 * red1) / 7;
+ case 6:
+ return (2 * red0 + 5 * red1) / 7;
+ case 7:
+ return (1 * red0 + 6 * red1) / 7;
+ }
+ } else {
+ switch (code) {
+ case 0:
+ return red0;
+ case 1:
+ return red1;
+ case 2:
+ return (4 * red0 + 1 * red1) / 5;
+ case 3:
+ return (3 * red0 + 2 * red1) / 5;
+ case 4:
+ return (2 * red0 + 3 * red1) / 5;
+ case 5:
+ return (1 * red0 + 4 * red1) / 5;
+ case 6:
+ return 0;
+ case 7:
+ return 0xff;
+ }
+ }
+ return 0;
+}
+
+void main() {
+ uvec2 packed_bits = imageLoad(bc4_input, ivec3(gl_WorkGroupID + src_offset)).rg;
+ uint64_t bits = packUint2x32(packed_bits);
+ uint red = DecompressBlock(bits, gl_LocalInvocationID.xy);
+ uvec4 color = uvec4(red & 0xff, 0, 0, 0xff);
+ imageStore(bc4_output, ivec3(gl_GlobalInvocationID + dst_offset), color);
+}