From 225f806eab24521f2bbf7da91118b14c2ebf6475 Mon Sep 17 00:00:00 2001
From: Samuliak <samuliak77@gmail.com>
Date: Tue, 2 Jul 2024 15:14:50 +0200
Subject: [PATCH] support etc texture formats
---
CMakeLists.txt | 1 +
src/core/renderer_mtl/etc1.cpp | 124 ++++++++++++++++++++++++++++++
src/core/renderer_mtl/texture.cpp | 10 +--
3 files changed, 127 insertions(+), 8 deletions(-)
create mode 100644 src/core/renderer_mtl/etc1.cpp
diff --git a/CMakeLists.txt b/CMakeLists.txt
index c5745d02..a2c704b0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -408,6 +408,7 @@ if(ENABLE_METAL AND APPLE)
set(RENDERER_MTL_SOURCE_FILES src/core/renderer_mtl/metal_cpp_impl.cpp
src/core/renderer_mtl/renderer_mtl.cpp
src/core/renderer_mtl/texture.cpp
+ src/core/renderer_mtl/etc1.cpp
src/host_shaders/metal_shaders.metal
)
diff --git a/src/core/renderer_mtl/etc1.cpp b/src/core/renderer_mtl/etc1.cpp
new file mode 100644
index 00000000..8018c2dc
--- /dev/null
+++ b/src/core/renderer_mtl/etc1.cpp
@@ -0,0 +1,124 @@
+#include <algorithm>
+#include "colour.hpp"
+#include "renderer_mtl/renderer_mtl.hpp"
+#include "renderer_mtl/texture.hpp"
+
+using namespace Helpers;
+
+namespace Metal {
+
+static constexpr u32 signExtend3To32(u32 val) {
+ return (u32)(s32(val) << 29 >> 29);
+}
+
+u32 Texture::getTexelETC(bool hasAlpha, u32 u, u32 v, u32 width, std::span<const u8> data) {
+ // Pixel offset of the 8x8 tile based on u, v and the width of the texture
+ u32 offs = ((u & ~7) * 8) + ((v & ~7) * width);
+ if (!hasAlpha)
+ offs >>= 1;
+
+ // In-tile offsets for u/v
+ u &= 7;
+ v &= 7;
+
+ // ETC1(A4) also subdivide the 8x8 tile to 4 4x4 tiles
+ // Each tile is 8 bytes for ETC1, but since ETC1A4 has 4 alpha bits per pixel, that becomes 16 bytes
+ const u32 subTileSize = hasAlpha ? 16 : 8;
+ const u32 subTileIndex = (u / 4) + 2 * (v / 4); // Which of the 4 subtiles is this texel in?
+
+ // In-subtile offsets for u/v
+ u &= 3;
+ v &= 3;
+ offs += subTileSize * subTileIndex;
+
+ u32 alpha;
+ const u64* ptr = reinterpret_cast<const u64*>(data.data() + offs); // Cast to u64*
+
+ if (hasAlpha) {
+ // First 64 bits of the 4x4 subtile are alpha data
+ const u64 alphaData = *ptr++;
+ alpha = Colour::convert4To8Bit((alphaData >> (4 * (u * 4 + v))) & 0xf);
+ }
+ else {
+ alpha = 0xff; // ETC1 without alpha uses ff for every pixel
+ }
+
+ // Next 64 bits of the subtile are colour data
+ u64 colourData = *ptr;
+ return decodeETC(alpha, u, v, colourData);
+}
+
+u32 Texture::decodeETC(u32 alpha, u32 u, u32 v, u64 colourData) {
+ static constexpr u32 modifiers[8][2] = {
+ { 2, 8 },
+ { 5, 17 },
+ { 9, 29 },
+ { 13, 42 },
+ { 18, 60 },
+ { 24, 80 },
+ { 33, 106 },
+ { 47, 183 },
+ };
+
+ // Parse colour data for 4x4 block
+ const u32 subindices = getBits<0, 16, u32>(colourData);
+ const u32 negationFlags = getBits<16, 16, u32>(colourData);
+ const bool flip = getBit<32>(colourData);
+ const bool diffMode = getBit<33>(colourData);
+
+ // Note: index1 is indeed stored on the higher bits, with index2 in the lower bits
+ const u32 tableIndex1 = getBits<37, 3, u32>(colourData);
+ const u32 tableIndex2 = getBits<34, 3, u32>(colourData);
+ const u32 texelIndex = u * 4 + v; // Index of the texel in the block
+
+ if (flip)
+ std::swap(u, v);
+
+ s32 r, g, b;
+ if (diffMode) {
+ r = getBits<59, 5, s32>(colourData);
+ g = getBits<51, 5, s32>(colourData);
+ b = getBits<43, 5, s32>(colourData);
+
+ if (u >= 2) {
+ r += signExtend3To32(getBits<56, 3, u32>(colourData));
+ g += signExtend3To32(getBits<48, 3, u32>(colourData));
+ b += signExtend3To32(getBits<40, 3, u32>(colourData));
+ }
+
+ // Expand from 5 to 8 bits per channel
+ r = Colour::convert5To8Bit(r);
+ g = Colour::convert5To8Bit(g);
+ b = Colour::convert5To8Bit(b);
+ } else {
+ if (u < 2) {
+ r = getBits<60, 4, s32>(colourData);
+ g = getBits<52, 4, s32>(colourData);
+ b = getBits<44, 4, s32>(colourData);
+ } else {
+ r = getBits<56, 4, s32>(colourData);
+ g = getBits<48, 4, s32>(colourData);
+ b = getBits<40, 4, s32>(colourData);
+ }
+
+ // Expand from 4 to 8 bits per channel
+ r = Colour::convert4To8Bit(r);
+ g = Colour::convert4To8Bit(g);
+ b = Colour::convert4To8Bit(b);
+ }
+
+ const u32 index = (u < 2) ? tableIndex1 : tableIndex2;
+ s32 modifier = modifiers[index][(subindices >> texelIndex) & 1];
+
+ if (((negationFlags >> texelIndex) & 1) != 0) {
+ modifier = -modifier;
+ }
+
+ r = std::clamp(r + modifier, 0, 255);
+ g = std::clamp(g + modifier, 0, 255);
+ b = std::clamp(b + modifier, 0, 255);
+
+ return (alpha << 24) | (u32(b) << 16) | (u32(g) << 8) | u32(r);
+}
+
+} // namespace Metal
diff --git a/src/core/renderer_mtl/texture.cpp b/src/core/renderer_mtl/texture.cpp
index a4c1dd4d..df3866ac 100644
--- a/src/core/renderer_mtl/texture.cpp
+++ b/src/core/renderer_mtl/texture.cpp
@@ -228,14 +228,8 @@ u32 Texture::decodeTexel(u32 u, u32 v, PICA::TextureFmt fmt, std::span<const u8>
return (alpha << 24) | (intensity << 16) | (intensity << 8) | intensity;
}
- case PICA::TextureFmt::ETC1: {
- //return getTexelETC(false, u, v, size.u(), data);
- Helpers::panic("[Texture::DecodeTexel] Unimplemented format = %d", static_cast<int>(fmt));
- }
- case PICA::TextureFmt::ETC1A4: {
- //return getTexelETC(true, u, v, size.u(), data);
- Helpers::panic("[Texture::DecodeTexel] Unimplemented format = %d", static_cast<int>(fmt));
- }
+ case PICA::TextureFmt::ETC1: return getTexelETC(false, u, v, size.u(), data);
+ case PICA::TextureFmt::ETC1A4: return getTexelETC(true, u, v, size.u(), data);
default:
Helpers::panic("[Texture::DecodeTexel] Unimplemented format = %d", static_cast<int>(fmt));