textures: add BC1 and BC3 compressors and recompression setting

src/video_core/textures/bcn.cpp

@@ -0,0 +1,87 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <stb_dxt.h>
+#include <string.h>
+
+#include "common/alignment.h"
+#include "video_core/textures/bcn.h"
+#include "video_core/textures/workers.h"
+
+namespace Tegra::Texture::BCN {
+
+using BCNCompressor = void(u8* block_output, const u8* block_input, bool any_alpha);
+
+template <u32 BytesPerBlock, bool ThresholdAlpha = false>
+void CompressBCN(std::span<const uint8_t> data, uint32_t width, uint32_t height, uint32_t depth,
+                 std::span<uint8_t> output, BCNCompressor f) {
+    constexpr u8 alpha_threshold = 128;
+    constexpr u32 bytes_per_px = 4;
+    const u32 plane_dim = width * height;
+
+    Common::ThreadWorker& workers{GetThreadWorkers()};
+
+    for (u32 z = 0; z < depth; z++) {
+        for (u32 y = 0; y < height; y += 4) {
+            auto compress_row = [z, y, width, height, plane_dim, f, data, output]() {
+                for (u32 x = 0; x < width; x += 4) {
+                    // Gather 4x4 block of RGBA texels
+                    u8 input_colors[4][4][4];
+                    bool any_alpha = false;
+
+                    for (u32 j = 0; j < 4; j++) {
+                        for (u32 i = 0; i < 4; i++) {
+                            const size_t coord =
+                                (z * plane_dim + (y + j) * width + (x + i)) * bytes_per_px;
+
+                            if ((x + i < width) && (y + j < height)) {
+                                if constexpr (ThresholdAlpha) {
+                                    if (data[coord + 3] >= alpha_threshold) {
+                                        input_colors[j][i][0] = data[coord + 0];
+                                        input_colors[j][i][1] = data[coord + 1];
+                                        input_colors[j][i][2] = data[coord + 2];
+                                        input_colors[j][i][3] = 255;
+                                    } else {
+                                        any_alpha = true;
+                                        memset(input_colors[j][i], 0, bytes_per_px);
+                                    }
+                                } else {
+                                    memcpy(input_colors[j][i], &data[coord], bytes_per_px);
+                                }
+                            } else {
+                                memset(input_colors[j][i], 0, bytes_per_px);
+                            }
+                        }
+                    }
+
+                    const u32 bytes_per_row = BytesPerBlock * Common::DivideUp(width, 4U);
+                    const u32 bytes_per_plane = bytes_per_row * Common::DivideUp(height, 4U);
+                    f(output.data() + z * bytes_per_plane + (y / 4) * bytes_per_row +
+                          (x / 4) * BytesPerBlock,
+                      reinterpret_cast<u8*>(input_colors), any_alpha);
+                }
+            };
+            workers.QueueWork(std::move(compress_row));
+        }
+        workers.WaitForRequests();
+    }
+}
+
+void CompressBC1(std::span<const uint8_t> data, uint32_t width, uint32_t height, uint32_t depth,
+                 std::span<uint8_t> output) {
+    CompressBCN<8, true>(data, width, height, depth, output,
+                         [](u8* block_output, const u8* block_input, bool any_alpha) {
+                             stb_compress_bc1_block(block_output, block_input, any_alpha,
+                                                    STB_DXT_NORMAL);
+                         });
+}
+
+void CompressBC3(std::span<const uint8_t> data, uint32_t width, uint32_t height, uint32_t depth,
+                 std::span<uint8_t> output) {
+    CompressBCN<16, false>(data, width, height, depth, output,
+                           [](u8* block_output, const u8* block_input, bool any_alpha) {
+                               stb_compress_bc3_block(block_output, block_input, STB_DXT_NORMAL);
+                           });
+}
+
+} // namespace Tegra::Texture::BCN