Index: cc/resources/texture_compressor_etc1.cc |
diff --git a/cc/resources/texture_compressor_etc1.cc b/cc/resources/texture_compressor_etc1.cc |
deleted file mode 100644 |
index 83c3f9fb034806a29bd86c669f405cae7256ddde..0000000000000000000000000000000000000000 |
--- a/cc/resources/texture_compressor_etc1.cc |
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-// Copyright 2015 The Chromium Authors. All rights reserved. |
-// Use of this source code is governed by a BSD-style license that can be |
-// found in the LICENSE file. |
- |
-// See the following specification for details on the ETC1 format: |
-// https://www.khronos.org/registry/gles/extensions/OES/OES_compressed_ETC1_RGB8_texture.txt |
- |
-#include "cc/resources/texture_compressor_etc1.h" |
- |
-#include <string.h> |
-#include <limits> |
- |
-#include "base/logging.h" |
- |
-// Defining the following macro will cause the error metric function to weigh |
-// each color channel differently depending on how the human eye can perceive |
-// them. This can give a slight improvement in image quality at the cost of a |
-// performance hit. |
-// #define USE_PERCEIVED_ERROR_METRIC |
- |
-namespace cc { |
- |
-namespace { |
- |
-// Constructs a color from a given base color and luminance value. |
-inline Color MakeColor(const Color& base, int16_t lum) { |
- int b = static_cast<int>(base.channels.b) + lum; |
- int g = static_cast<int>(base.channels.g) + lum; |
- int r = static_cast<int>(base.channels.r) + lum; |
- Color color; |
- color.channels.b = static_cast<uint8_t>(clamp(b, 0, 255)); |
- color.channels.g = static_cast<uint8_t>(clamp(g, 0, 255)); |
- color.channels.r = static_cast<uint8_t>(clamp(r, 0, 255)); |
- return color; |
-} |
- |
-// Calculates the error metric for two colors. A small error signals that the |
-// colors are similar to each other, a large error the signals the opposite. |
-inline uint32_t GetColorError(const Color& u, const Color& v) { |
-#ifdef USE_PERCEIVED_ERROR_METRIC |
- float delta_b = static_cast<float>(u.channels.b) - v.channels.b; |
- float delta_g = static_cast<float>(u.channels.g) - v.channels.g; |
- float delta_r = static_cast<float>(u.channels.r) - v.channels.r; |
- return static_cast<uint32_t>(0.299f * delta_b * delta_b + |
- 0.587f * delta_g * delta_g + |
- 0.114f * delta_r * delta_r); |
-#else |
- int delta_b = static_cast<int>(u.channels.b) - v.channels.b; |
- int delta_g = static_cast<int>(u.channels.g) - v.channels.g; |
- int delta_r = static_cast<int>(u.channels.r) - v.channels.r; |
- return delta_b * delta_b + delta_g * delta_g + delta_r * delta_r; |
-#endif |
-} |
- |
-void GetAverageColor(const Color* src, float* avg_color) { |
- uint32_t sum_b = 0, sum_g = 0, sum_r = 0; |
- |
- for (unsigned int i = 0; i < 8; ++i) { |
- sum_b += src[i].channels.b; |
- sum_g += src[i].channels.g; |
- sum_r += src[i].channels.r; |
- } |
- |
- const float kInv8 = 1.0f / 8.0f; |
- avg_color[0] = static_cast<float>(sum_b) * kInv8; |
- avg_color[1] = static_cast<float>(sum_g) * kInv8; |
- avg_color[2] = static_cast<float>(sum_r) * kInv8; |
-} |
- |
-void ComputeLuminance(uint8_t* block, |
- const Color* src, |
- const Color& base, |
- int sub_block_id, |
- const uint8_t* idx_to_num_tab) { |
- uint32_t best_tbl_err = std::numeric_limits<uint32_t>::max(); |
- uint8_t best_tbl_idx = 0; |
- uint8_t best_mod_idx[8][8]; // [table][texel] |
- |
- // Try all codeword tables to find the one giving the best results for this |
- // block. |
- for (unsigned int tbl_idx = 0; tbl_idx < 8; ++tbl_idx) { |
- // Pre-compute all the candidate colors; combinations of the base color and |
- // all available luminance values. |
- Color candidate_color[4]; // [modifier] |
- for (unsigned int mod_idx = 0; mod_idx < 4; ++mod_idx) { |
- int16_t lum = g_codeword_tables[tbl_idx][mod_idx]; |
- candidate_color[mod_idx] = MakeColor(base, lum); |
- } |
- |
- uint32_t tbl_err = 0; |
- |
- for (unsigned int i = 0; i < 8; ++i) { |
- // Try all modifiers in the current table to find which one gives the |
- // smallest error. |
- uint32_t best_mod_err = std::numeric_limits<uint32_t>::max(); |
- for (unsigned int mod_idx = 0; mod_idx < 4; ++mod_idx) { |
- const Color& color = candidate_color[mod_idx]; |
- |
- uint32_t mod_err = GetColorError(src[i], color); |
- if (mod_err < best_mod_err) { |
- best_mod_idx[tbl_idx][i] = mod_idx; |
- best_mod_err = mod_err; |
- |
- if (mod_err == 0) |
- break; // We cannot do any better than this. |
- } |
- } |
- |
- tbl_err += best_mod_err; |
- if (tbl_err > best_tbl_err) |
- break; // We're already doing worse than the best table so skip. |
- } |
- |
- if (tbl_err < best_tbl_err) { |
- best_tbl_err = tbl_err; |
- best_tbl_idx = tbl_idx; |
- |
- if (tbl_err == 0) |
- break; // We cannot do any better than this. |
- } |
- } |
- |
- WriteCodewordTable(block, sub_block_id, best_tbl_idx); |
- |
- uint32_t pix_data = 0; |
- |
- for (unsigned int i = 0; i < 8; ++i) { |
- uint8_t mod_idx = best_mod_idx[best_tbl_idx][i]; |
- uint8_t pix_idx = g_mod_to_pix[mod_idx]; |
- |
- uint32_t lsb = pix_idx & 0x1; |
- uint32_t msb = pix_idx >> 1; |
- |
- // Obtain the texel number as specified in the standard. |
- int texel_num = idx_to_num_tab[i]; |
- pix_data |= msb << (texel_num + 16); |
- pix_data |= lsb << (texel_num); |
- } |
- |
- WritePixelData(block, pix_data); |
-} |
- |
-/** |
- * Tries to compress the block under the assumption that it's a single color |
- * block. If it's not the function will bail out without writing anything to |
- * the destination buffer. |
- */ |
-bool TryCompressSolidBlock(uint8_t* dst, const Color* src) { |
- for (unsigned int i = 1; i < 16; ++i) { |
- if (src[i].bits != src[0].bits) |
- return false; |
- } |
- |
- // Clear destination buffer so that we can "or" in the results. |
- memset(dst, 0, 8); |
- |
- float src_color_float[3] = {static_cast<float>(src->channels.b), |
- static_cast<float>(src->channels.g), |
- static_cast<float>(src->channels.r)}; |
- Color base = MakeColor555(src_color_float); |
- |
- WriteDiff(dst, true); |
- WriteFlip(dst, false); |
- WriteColors555(dst, base, base); |
- |
- uint8_t best_tbl_idx = 0; |
- uint8_t best_mod_idx = 0; |
- uint32_t best_mod_err = std::numeric_limits<uint32_t>::max(); |
- |
- // Try all codeword tables to find the one giving the best results for this |
- // block. |
- for (unsigned int tbl_idx = 0; tbl_idx < 8; ++tbl_idx) { |
- // Try all modifiers in the current table to find which one gives the |
- // smallest error. |
- for (unsigned int mod_idx = 0; mod_idx < 4; ++mod_idx) { |
- int16_t lum = g_codeword_tables[tbl_idx][mod_idx]; |
- const Color& color = MakeColor(base, lum); |
- |
- uint32_t mod_err = GetColorError(*src, color); |
- if (mod_err < best_mod_err) { |
- best_tbl_idx = tbl_idx; |
- best_mod_idx = mod_idx; |
- best_mod_err = mod_err; |
- |
- if (mod_err == 0) |
- break; // We cannot do any better than this. |
- } |
- } |
- |
- if (best_mod_err == 0) |
- break; |
- } |
- |
- WriteCodewordTable(dst, 0, best_tbl_idx); |
- WriteCodewordTable(dst, 1, best_tbl_idx); |
- |
- uint8_t pix_idx = g_mod_to_pix[best_mod_idx]; |
- uint32_t lsb = pix_idx & 0x1; |
- uint32_t msb = pix_idx >> 1; |
- |
- uint32_t pix_data = 0; |
- for (unsigned int i = 0; i < 2; ++i) { |
- for (unsigned int j = 0; j < 8; ++j) { |
- // Obtain the texel number as specified in the standard. |
- int texel_num = g_idx_to_num[i][j]; |
- pix_data |= msb << (texel_num + 16); |
- pix_data |= lsb << (texel_num); |
- } |
- } |
- |
- WritePixelData(dst, pix_data); |
- return true; |
-} |
- |
-void CompressBlock(uint8_t* dst, const Color* ver_src, const Color* hor_src) { |
- if (TryCompressSolidBlock(dst, ver_src)) |
- return; |
- |
- const Color* sub_block_src[4] = {ver_src, ver_src + 8, hor_src, hor_src + 8}; |
- |
- Color sub_block_avg[4]; |
- bool use_differential[2] = {true, true}; |
- |
- // Compute the average color for each sub block and determine if differential |
- // coding can be used. |
- for (unsigned int i = 0, j = 1; i < 4; i += 2, j += 2) { |
- float avg_color_0[3]; |
- GetAverageColor(sub_block_src[i], avg_color_0); |
- Color avg_color_555_0 = MakeColor555(avg_color_0); |
- |
- float avg_color_1[3]; |
- GetAverageColor(sub_block_src[j], avg_color_1); |
- Color avg_color_555_1 = MakeColor555(avg_color_1); |
- |
- for (unsigned int light_idx = 0; light_idx < 3; ++light_idx) { |
- int u = avg_color_555_0.components[light_idx] >> 3; |
- int v = avg_color_555_1.components[light_idx] >> 3; |
- |
- int component_diff = v - u; |
- if (component_diff < -4 || component_diff > 3) { |
- use_differential[i / 2] = false; |
- sub_block_avg[i] = MakeColor444(avg_color_0); |
- sub_block_avg[j] = MakeColor444(avg_color_1); |
- } else { |
- sub_block_avg[i] = avg_color_555_0; |
- sub_block_avg[j] = avg_color_555_1; |
- } |
- } |
- } |
- |
- // Compute the error of each sub block before adjusting for luminance. These |
- // error values are later used for determining if we should flip the sub |
- // block or not. |
- uint32_t sub_block_err[4] = {0}; |
- for (unsigned int i = 0; i < 4; ++i) { |
- for (unsigned int j = 0; j < 8; ++j) { |
- sub_block_err[i] += GetColorError(sub_block_avg[i], sub_block_src[i][j]); |
- } |
- } |
- |
- bool flip = |
- sub_block_err[2] + sub_block_err[3] < sub_block_err[0] + sub_block_err[1]; |
- |
- // Clear destination buffer so that we can "or" in the results. |
- memset(dst, 0, 8); |
- |
- WriteDiff(dst, use_differential[!!flip]); |
- WriteFlip(dst, flip); |
- |
- uint8_t sub_block_off_0 = flip ? 2 : 0; |
- uint8_t sub_block_off_1 = sub_block_off_0 + 1; |
- |
- if (use_differential[!!flip]) { |
- WriteColors555(dst, sub_block_avg[sub_block_off_0], |
- sub_block_avg[sub_block_off_1]); |
- } else { |
- WriteColors444(dst, sub_block_avg[sub_block_off_0], |
- sub_block_avg[sub_block_off_1]); |
- } |
- |
- // Compute luminance for the first sub block. |
- ComputeLuminance(dst, sub_block_src[sub_block_off_0], |
- sub_block_avg[sub_block_off_0], 0, |
- g_idx_to_num[sub_block_off_0]); |
- // Compute luminance for the second sub block. |
- ComputeLuminance(dst, sub_block_src[sub_block_off_1], |
- sub_block_avg[sub_block_off_1], 1, |
- g_idx_to_num[sub_block_off_1]); |
-} |
- |
-} // namespace |
- |
-void TextureCompressorETC1::Compress(const uint8_t* src, |
- uint8_t* dst, |
- int width, |
- int height, |
- Quality quality) { |
- DCHECK_GE(width, 4); |
- DCHECK_EQ((width & 3), 0); |
- DCHECK_GE(height, 4); |
- DCHECK_EQ((height & 3), 0); |
- |
- Color ver_blocks[16]; |
- Color hor_blocks[16]; |
- |
- for (int y = 0; y < height; y += 4, src += width * 4 * 4) { |
- for (int x = 0; x < width; x += 4, dst += 8) { |
- const Color* row0 = reinterpret_cast<const Color*>(src + x * 4); |
- const Color* row1 = row0 + width; |
- const Color* row2 = row1 + width; |
- const Color* row3 = row2 + width; |
- |
- memcpy(ver_blocks, row0, 8); |
- memcpy(ver_blocks + 2, row1, 8); |
- memcpy(ver_blocks + 4, row2, 8); |
- memcpy(ver_blocks + 6, row3, 8); |
- memcpy(ver_blocks + 8, row0 + 2, 8); |
- memcpy(ver_blocks + 10, row1 + 2, 8); |
- memcpy(ver_blocks + 12, row2 + 2, 8); |
- memcpy(ver_blocks + 14, row3 + 2, 8); |
- |
- memcpy(hor_blocks, row0, 16); |
- memcpy(hor_blocks + 4, row1, 16); |
- memcpy(hor_blocks + 8, row2, 16); |
- memcpy(hor_blocks + 12, row3, 16); |
- |
- CompressBlock(dst, ver_blocks, hor_blocks); |
- } |
- } |
-} |
- |
-} // namespace cc |