mirror of https://github.com/axmolengine/axmol.git
287 lines
11 KiB
C++
287 lines
11 KiB
C++
// ----------------------------------------------------------------------------
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// This confidential and proprietary software may be used only as authorised
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// by a licensing agreement from Arm Limited.
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// (C) COPYRIGHT 2011-2019 Arm Limited, ALL RIGHTS RESERVED
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// The entire notice above must be reproduced on all authorised copies and
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// copies may only be made to the extent permitted by a licensing agreement
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// from Arm Limited.
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// ----------------------------------------------------------------------------
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/**
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* @brief Functions for finding color error post-compression.
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*
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* We assume there are two independent sources of error in any given partition.
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* - encoding choice errors
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* - quantization errors
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*
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* Encoding choice errors are caused by encoder decisions, such as:
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* - using luminance rather than RGB.
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* - using RGB+scale instead of two full RGB endpoints.
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* - dropping the alpha channel.
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*
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* Quantization errors occur due to the limited precision we use for storage.
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* These errors generally scale with quantization level, but are not actually
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* independent of color encoding. In particular:
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* - if we can use offset encoding then quantization error is halved.
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* - if we can use blue-contraction, quantization error for RG is halved.
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* - quantization error is higher for the HDR endpoint modes.
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* Other than these errors, quantization error is assumed to be proportional to
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* the quantization step.
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*/
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#include "astc_codec_internals.h"
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#ifdef DEBUG_PRINT_DIAGNOSTICS
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#include <stdio.h>
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#endif
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// helper function to merge two endpoint-colors
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void merge_endpoints(const endpoints * ep1, // contains three of the color components
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const endpoints * ep2, // contains the remaining color component
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int separate_component, endpoints * res)
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{
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int i;
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int partition_count = ep1->partition_count;
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res->partition_count = partition_count;
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for (i = 0; i < partition_count; i++)
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{
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res->endpt0[i] = ep1->endpt0[i];
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res->endpt1[i] = ep1->endpt1[i];
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}
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switch (separate_component)
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{
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case 0:
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for (i = 0; i < partition_count; i++)
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{
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res->endpt0[i].x = ep2->endpt0[i].x;
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res->endpt1[i].x = ep2->endpt1[i].x;
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}
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break;
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case 1:
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for (i = 0; i < partition_count; i++)
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{
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res->endpt0[i].y = ep2->endpt0[i].y;
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res->endpt1[i].y = ep2->endpt1[i].y;
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}
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break;
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case 2:
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for (i = 0; i < partition_count; i++)
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{
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res->endpt0[i].z = ep2->endpt0[i].z;
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res->endpt1[i].z = ep2->endpt1[i].z;
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}
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break;
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case 3:
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for (i = 0; i < partition_count; i++)
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{
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res->endpt0[i].w = ep2->endpt0[i].w;
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res->endpt1[i].w = ep2->endpt1[i].w;
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}
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break;
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}
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}
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/*
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for a given set of input colors and a given partitioning, determine: color error that results
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from RGB-scale encoding (relevant for LDR only) color error that results from RGB-lumashift encoding
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(relevant for HDR only) color error that results from luminance-encoding color error that results
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form dropping alpha. whether we are eligible for offset encoding whether we are eligible for
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blue-contraction
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The input data are: color data partitioning error-weight data
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*/
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void compute_encoding_choice_errors(int xdim, int ydim, int zdim, const imageblock * pb, const partition_info * pi, const error_weight_block * ewb,
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int separate_component, // component that is separated out in 2-plane mode, -1 in 1-plane mode
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encoding_choice_errors * eci)
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{
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int i;
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int partition_count = pi->partition_count;
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int texels_per_block = xdim * ydim * zdim;
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#ifdef DEBUG_PRINT_DIAGNOSTICS
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if (print_diagnostics)
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{
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printf("%s : texels-per-block=%dx%dx%d, separate_component=%d, partition-count=%d\n", __func__, xdim, ydim, zdim, separate_component, partition_count);
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}
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#endif
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float3 averages[4];
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float3 directions_rgb[4];
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float2 directions_rg[4];
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float2 directions_rb[4];
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float2 directions_gb[4];
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float4 error_weightings[4];
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float4 color_scalefactors[4];
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float4 inverse_color_scalefactors[4];
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compute_partition_error_color_weightings(xdim, ydim, zdim, ewb, pi, error_weightings, color_scalefactors);
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compute_averages_and_directions_rgb(pi, pb, ewb, color_scalefactors, averages, directions_rgb, directions_rg, directions_rb, directions_gb);
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line3 uncorr_rgb_lines[4];
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line3 samechroma_rgb_lines[4]; // for LDR-RGB-scale
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line3 rgb_luma_lines[4]; // for HDR-RGB-scale
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line3 luminance_lines[4];
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processed_line3 proc_uncorr_rgb_lines[4];
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processed_line3 proc_samechroma_rgb_lines[4]; // for LDR-RGB-scale
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processed_line3 proc_rgb_luma_lines[4]; // for HDR-RGB-scale
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processed_line3 proc_luminance_lines[4];
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for (i = 0; i < partition_count; i++)
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{
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inverse_color_scalefactors[i].x = 1.0f / MAX(color_scalefactors[i].x, 1e-7f);
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inverse_color_scalefactors[i].y = 1.0f / MAX(color_scalefactors[i].y, 1e-7f);
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inverse_color_scalefactors[i].z = 1.0f / MAX(color_scalefactors[i].z, 1e-7f);
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inverse_color_scalefactors[i].w = 1.0f / MAX(color_scalefactors[i].w, 1e-7f);
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uncorr_rgb_lines[i].a = averages[i];
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if (dot(directions_rgb[i], directions_rgb[i]) == 0.0f)
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uncorr_rgb_lines[i].b = normalize(float3(color_scalefactors[i].xyz));
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else
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uncorr_rgb_lines[i].b = normalize(directions_rgb[i]);
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samechroma_rgb_lines[i].a = float3(0, 0, 0);
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if (dot(averages[i], averages[i]) < 1e-20)
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samechroma_rgb_lines[i].b = normalize(float3(color_scalefactors[i].xyz));
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else
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samechroma_rgb_lines[i].b = normalize(averages[i]);
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rgb_luma_lines[i].a = averages[i];
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rgb_luma_lines[i].b = normalize(color_scalefactors[i].xyz);
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luminance_lines[i].a = float3(0, 0, 0);
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luminance_lines[i].b = normalize(color_scalefactors[i].xyz);
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#ifdef DEBUG_PRINT_DIAGNOSTICS
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if (print_diagnostics)
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{
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printf("Partition %d\n", i);
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printf("Average = <%g %g %g>\n", averages[i].x, averages[i].y, averages[i].z);
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printf("Uncorr-rgb-line = <%g %g %g> + t<%g %g %g>\n",
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uncorr_rgb_lines[i].a.x, uncorr_rgb_lines[i].a.y, uncorr_rgb_lines[i].a.z, uncorr_rgb_lines[i].b.x, uncorr_rgb_lines[i].b.y, uncorr_rgb_lines[i].b.z);
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printf("Samechroma-line = t<%g %g %g>\n", samechroma_rgb_lines[i].b.x, samechroma_rgb_lines[i].b.y, samechroma_rgb_lines[i].b.z);
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}
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#endif
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proc_uncorr_rgb_lines[i].amod = (uncorr_rgb_lines[i].a - uncorr_rgb_lines[i].b * dot(uncorr_rgb_lines[i].a, uncorr_rgb_lines[i].b)) * inverse_color_scalefactors[i].xyz;
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proc_uncorr_rgb_lines[i].bs = uncorr_rgb_lines[i].b * color_scalefactors[i].xyz;
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proc_uncorr_rgb_lines[i].bis = uncorr_rgb_lines[i].b * inverse_color_scalefactors[i].xyz;
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proc_samechroma_rgb_lines[i].amod = (samechroma_rgb_lines[i].a - samechroma_rgb_lines[i].b * dot(samechroma_rgb_lines[i].a, samechroma_rgb_lines[i].b)) * inverse_color_scalefactors[i].xyz;
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proc_samechroma_rgb_lines[i].bs = samechroma_rgb_lines[i].b * color_scalefactors[i].xyz;
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proc_samechroma_rgb_lines[i].bis = samechroma_rgb_lines[i].b * inverse_color_scalefactors[i].xyz;
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proc_rgb_luma_lines[i].amod = (rgb_luma_lines[i].a - rgb_luma_lines[i].b * dot(rgb_luma_lines[i].a, rgb_luma_lines[i].b)) * inverse_color_scalefactors[i].xyz;
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proc_rgb_luma_lines[i].bs = rgb_luma_lines[i].b * color_scalefactors[i].xyz;
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proc_rgb_luma_lines[i].bis = rgb_luma_lines[i].b * inverse_color_scalefactors[i].xyz;
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proc_luminance_lines[i].amod = (luminance_lines[i].a - luminance_lines[i].b * dot(luminance_lines[i].a, luminance_lines[i].b)) * inverse_color_scalefactors[i].xyz;
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proc_luminance_lines[i].bs = luminance_lines[i].b * color_scalefactors[i].xyz;
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proc_luminance_lines[i].bis = luminance_lines[i].b * inverse_color_scalefactors[i].xyz;
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}
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float uncorr_rgb_error[4];
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float samechroma_rgb_error[4];
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float rgb_luma_error[4];
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float luminance_rgb_error[4];
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for (i = 0; i < partition_count; i++)
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{
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uncorr_rgb_error[i] = compute_error_squared_rgb_single_partition(i, xdim, ydim, zdim, pi, pb, ewb, &(proc_uncorr_rgb_lines[i]));
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samechroma_rgb_error[i] = compute_error_squared_rgb_single_partition(i, xdim, ydim, zdim, pi, pb, ewb, &(proc_samechroma_rgb_lines[i]));
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rgb_luma_error[i] = compute_error_squared_rgb_single_partition(i, xdim, ydim, zdim, pi, pb, ewb, &(proc_rgb_luma_lines[i]));
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luminance_rgb_error[i] = compute_error_squared_rgb_single_partition(i, xdim, ydim, zdim, pi, pb, ewb, &(proc_luminance_lines[i]));
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#ifdef DEBUG_PRINT_DIAGNOSTICS
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if (print_diagnostics)
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{
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printf("Partition %d : uncorr-error=%g samechroma-error=%g rgb-luma-error=%g lum-error=%g\n",
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i, uncorr_rgb_error[i], samechroma_rgb_error[i], rgb_luma_error[i], luminance_rgb_error[i]);
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}
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#endif
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}
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// compute the error that arises from just ditching alpha and RGB
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float alpha_drop_error[4];
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float rgb_drop_error[4];
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for (i = 0; i < partition_count; i++)
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{
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alpha_drop_error[i] = 0;
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rgb_drop_error[i] = 0;
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}
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for (i = 0; i < texels_per_block; i++)
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{
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int partition = pi->partition_of_texel[i];
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float alpha = pb->work_data[4 * i + 3];
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float default_alpha = pb->alpha_lns[i] ? (float)0x7800 : (float)0xFFFF;
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float omalpha = alpha - default_alpha;
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alpha_drop_error[partition] += omalpha * omalpha * ewb->error_weights[i].w;
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float red = pb->work_data[4 * i];
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float green = pb->work_data[4 * i + 1];
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float blue = pb->work_data[4 * i + 2];
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rgb_drop_error[partition] += red * red * ewb->error_weights[i].x + green * green * ewb->error_weights[i].y + blue * blue * ewb->error_weights[i].z;
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}
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// check if we are eligible for blue-contraction and offset-encoding
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endpoints ep;
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if (separate_component == -1)
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{
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endpoints_and_weights ei;
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compute_endpoints_and_ideal_weights_1_plane(xdim, ydim, zdim, pi, pb, ewb, &ei);
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ep = ei.ep;
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}
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else
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{
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endpoints_and_weights ei1, ei2;
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compute_endpoints_and_ideal_weights_2_planes(xdim, ydim, zdim, pi, pb, ewb, separate_component, &ei1, &ei2);
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merge_endpoints(&(ei1.ep), &(ei2.ep), separate_component, &ep);
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}
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int eligible_for_offset_encode[4];
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int eligible_for_blue_contraction[4];
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for (i = 0; i < partition_count; i++)
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{
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float4 endpt0 = ep.endpt0[i];
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float4 endpt1 = ep.endpt1[i];
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float4 endpt_dif = endpt1 - endpt0;
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if (fabs(endpt_dif.x) < (0.12 * 65535.0f) && fabs(endpt_dif.y) < (0.12 * 65535.0f) && fabs(endpt_dif.z) < (0.12 * 65535.0f))
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eligible_for_offset_encode[i] = 1;
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else
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eligible_for_offset_encode[i] = 0;
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endpt0.x += (endpt0.x - endpt0.z);
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endpt0.y += (endpt0.y - endpt0.z);
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endpt1.x += (endpt1.x - endpt1.z);
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endpt1.y += (endpt1.y - endpt1.z);
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if (endpt0.x > (0.01f * 65535.0f) && endpt0.x < (0.99f * 65535.0f)
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&& endpt1.x > (0.01f * 65535.0f) && endpt1.x < (0.99f * 65535.0f)
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&& endpt0.y > (0.01f * 65535.0f) && endpt0.y < (0.99f * 65535.0f) && endpt1.y > (0.01f * 65535.0f) && endpt1.y < (0.99f * 65535.0f))
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eligible_for_blue_contraction[i] = 1;
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else
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eligible_for_blue_contraction[i] = 0;
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}
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// finally, gather up our results
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for (i = 0; i < partition_count; i++)
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{
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eci[i].rgb_scale_error = (samechroma_rgb_error[i] - uncorr_rgb_error[i]) * 0.7f; // empirical
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eci[i].rgb_luma_error = (rgb_luma_error[i] - uncorr_rgb_error[i]) * 1.5f; // wild guess
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eci[i].luminance_error = (luminance_rgb_error[i] - uncorr_rgb_error[i]) * 3.0f; // empirical
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eci[i].alpha_drop_error = alpha_drop_error[i] * 3.0f;
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eci[i].rgb_drop_error = rgb_drop_error[i] * 3.0f;
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eci[i].can_offset_encode = eligible_for_offset_encode[i];
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eci[i].can_blue_contract = eligible_for_blue_contraction[i];
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}
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}
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