post_shader_ssao.cpp

Go to the documentation of this file.

/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2015-2016 Mario Luzeiro <[email protected]>
 * Copyright (C) 2015-2024 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, you may find one here:
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * or you may search the http://www.gnu.org website for the version 2 license,
 * or you may write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
#include "post_shader_ssao.h"
#include "../3d_fastmath.h"
 
 
POST_SHADER_SSAO::POST_SHADER_SSAO( const CAMERA& aCamera ) :
 POST_SHADER( aCamera ),
 m_shadedBuffer( nullptr ),
 m_isUsingShadows( false )
{
}
 
// There are different sources for this shader on the web
//https://github.com/scanberg/hbao/blob/master/resources/shaders/ssao_frag.glsl
 
//http://www.gamedev.net/topic/556187-the-best-ssao-ive-seen/
//http://www.gamedev.net/topic/556187-the-best-ssao-ive-seen/?view=findpost&p=4632208
 
float POST_SHADER_SSAO::aoFF( const SFVEC2I& aShaderPos, const SFVEC3F& ddiff,
 const SFVEC3F& cnorm, const float aShadowAtSamplePos,
 const float aShadowAtCenterPos, int c1, int c2 ) const
{
 const float shadowGain = 0.60f;
 const float aoGain = 1.0f;
 
 const float shadow_factor_at_sample = ( 1.0f - aShadowAtSamplePos ) * shadowGain;
 const float shadow_factor_at_center = ( 1.0f - aShadowAtCenterPos ) * shadowGain;
 
 float return_value = shadow_factor_at_center;
 
 const float rd = glm::length( ddiff );
 
 // This limits the zero of the function (see below)
 if( rd < 2.0f )
 {
 if( rd > FLT_EPSILON )
 {
 const SFVEC3F vv = glm::normalize( ddiff );
 
 // Calculate an attenuation distance factor, this was get the best
 // results by experimentation
 // Changing this factor will change how much shadow in relation to the
 // distance of the hit it will be in shadow
 
 // http://www.fooplot.com/#W3sidHlwZSI6MCwiZXEiOiIwLjgteCowLjYiLCJjb2xvciI6IiMwMDAwMDAifSx7InR5cGUiOjAsImVxIjoiMS8oeCp4KjAuNSsxKSIsImNvbG9yIjoiIzAwMDAwMCJ9LHsidHlwZSI6MTAwMCwid2luZG93IjpbIi0yLjU5Mjk0NTkyNTA5ODA0MSIsIjQuNTUzODc5NjU1NDQ1OTIzIiwiLTEuNzY3MDMwOTAzMjgxNjgxOCIsIjIuNjMxMDE1NjA3ODIyMjk3Il0sInNpemUiOls2NDksMzk5XX1d
 const float attDistFactor = 1.0f / ( rd * rd * 8.0f + 1.0f );
 
 const SFVEC2I vr = aShaderPos + SFVEC2I( c1, c2 );
 
 float sampledNormalFactor = glm::max( glm::dot( GetNormalAt( vr ), cnorm ), 0.0f );
 
 sampledNormalFactor = glm::max( 1.0f - sampledNormalFactor *
 sampledNormalFactor, 0.0f );
 
 const float shadowAttDistFactor = glm::max( glm::min( rd * 5.0f - 0.25f, 1.0f ), 0.0f );
 
 float shadowAttFactor = glm::min( sampledNormalFactor + shadowAttDistFactor, 1.0f );
 
 const float shadowFactor = glm::mix( shadow_factor_at_sample, shadow_factor_at_center,
 shadowAttFactor );
 
 // This is a dot product threshold factor.
 // it defines after which angle we consider that the point starts to occlude.
 // if the value is high, it will discard low angles point
 const float aDotThreshold = 0.15f;
 
 // This is the dot product between the center pixel normal (the one that is being
 // shaded) and the vector from the center to the sampled point
 const float localNormalFactor = glm::dot( cnorm, vv );
 
 const float localNormalFactorWithThreshold =
 ( glm::max( localNormalFactor, aDotThreshold ) - aDotThreshold ) /
 ( 1.0f - aDotThreshold );
 
 const float aoFactor = localNormalFactorWithThreshold * aoGain * attDistFactor;
 
 return_value = glm::min( aoFactor + shadowFactor, 1.0f );
 }
 }
 
 return return_value;
}
 
 
float POST_SHADER_SSAO::giFF( const SFVEC2I& aShaderPos, const SFVEC3F& ddiff,
 const SFVEC3F& cnorm, const float aShadow, int c1, int c2 ) const
{
 if( ( ddiff.x > FLT_EPSILON ) || ( ddiff.y > FLT_EPSILON ) || ( ddiff.z > FLT_EPSILON ) )
 {
 const SFVEC3F vv = glm::normalize( ddiff );
 const float rd = glm::length( ddiff );
 const SFVEC2I vr = aShaderPos + SFVEC2I( c1, c2 );
 
 const float attDistFactor = 1.0f / ( rd * rd + 1.0f );
 
 return ( glm::clamp( glm::dot( GetNormalAt( vr ), -vv), 0.0f, 1.0f ) *
 glm::clamp( glm::dot( cnorm, vv ), 0.0f, 1.0f ) * attDistFactor ) *
 ( 0.03f + aShadow ) * 3.0f;
 }
 
 return 0.0f;
}
 
 
SFVEC3F POST_SHADER_SSAO::Shade( const SFVEC2I& aShaderPos ) const
{
 float cdepth = GetDepthAt( aShaderPos );
 
 if( cdepth > FLT_EPSILON )
 {
 cdepth = ( 30.0f / ( cdepth * 2.0f + 1.0f ) );
 
 // read current normal, position and color.
 const SFVEC3F n = GetNormalAt( aShaderPos );
 const SFVEC3F p = GetPositionAt( aShaderPos );
 
 const float shadowAt0 = GetShadowFactorAt( aShaderPos );
 
 // initialize variables:
 float ao = 0.0f;
 SFVEC3F gi = SFVEC3F( 0.0f );
 
#define ROUNDS 3
 for( unsigned int i = 0; i < ROUNDS; ++i )
 {
 static const int limit[ROUNDS] = { 0x01, 0x03, 0x03 };
 
 const int pw = Fast_rand() & limit[i];
 const int ph = Fast_rand() & limit[i];
 
 const int npw = (int) ( ( pw + i ) * cdepth ) + ( i + 1 );
 const int nph = (int) ( ( ph + i ) * cdepth ) + ( i + 1 );
 
 const SFVEC3F ddiff = GetPositionAt( aShaderPos + SFVEC2I( npw, nph ) ) - p;
 const SFVEC3F ddiff2 = GetPositionAt( aShaderPos + SFVEC2I( npw, -nph ) ) - p;
 const SFVEC3F ddiff3 = GetPositionAt( aShaderPos + SFVEC2I( -npw, nph ) ) - p;
 const SFVEC3F ddiff4 = GetPositionAt( aShaderPos + SFVEC2I( -npw, -nph ) ) - p;
 const SFVEC3F ddiff5 = GetPositionAt( aShaderPos + SFVEC2I( pw, nph ) ) - p;
 const SFVEC3F ddiff6 = GetPositionAt( aShaderPos + SFVEC2I( pw, -nph ) ) - p;
 const SFVEC3F ddiff7 = GetPositionAt( aShaderPos + SFVEC2I( npw, ph ) ) - p;
 const SFVEC3F ddiff8 = GetPositionAt( aShaderPos + SFVEC2I(-npw, ph ) ) - p;
 
 const float shadowAt1 = GetShadowFactorAt( aShaderPos + SFVEC2I( +npw, nph ) );
 const float shadowAt2 = GetShadowFactorAt( aShaderPos + SFVEC2I( +npw, -nph ) );
 const float shadowAt3 = GetShadowFactorAt( aShaderPos + SFVEC2I( -npw, nph ) );
 const float shadowAt4 = GetShadowFactorAt( aShaderPos + SFVEC2I( -npw, -nph ) );
 const float shadowAt5 = GetShadowFactorAt( aShaderPos + SFVEC2I( +pw, nph ) );
 const float shadowAt6 = GetShadowFactorAt( aShaderPos + SFVEC2I( pw, -nph ) );
 const float shadowAt7 = GetShadowFactorAt( aShaderPos + SFVEC2I( npw, ph ) );
 const float shadowAt8 = GetShadowFactorAt( aShaderPos + SFVEC2I( -npw, ph ) );
 
 ao += aoFF( aShaderPos, ddiff , n, shadowAt1, shadowAt0, npw, nph );
 ao += aoFF( aShaderPos, ddiff2, n, shadowAt2, shadowAt0, npw, -nph );
 ao += aoFF( aShaderPos, ddiff3, n, shadowAt3, shadowAt0, -npw, nph );
 ao += aoFF( aShaderPos, ddiff4, n, shadowAt4, shadowAt0, -npw, -nph );
 ao += aoFF( aShaderPos, ddiff5, n, shadowAt5, shadowAt0, pw, nph );
 ao += aoFF( aShaderPos, ddiff6, n, shadowAt6, shadowAt0, pw, -nph );
 ao += aoFF( aShaderPos, ddiff7, n, shadowAt7, shadowAt0, npw, ph );
 ao += aoFF( aShaderPos, ddiff8, n, shadowAt8, shadowAt0, -npw, ph );
 
 gi += giFF( aShaderPos, ddiff , n, shadowAt1, npw, nph) *
 giColorCurveShade( GetColorAt( aShaderPos + SFVEC2I( npw, nph ) ) );
 gi += giFF( aShaderPos, ddiff2, n, shadowAt2, npw, -nph) *
 giColorCurveShade( GetColorAt( aShaderPos + SFVEC2I( npw,-nph ) ) );
 gi += giFF( aShaderPos, ddiff3, n, shadowAt3, -npw, nph) *
 giColorCurveShade( GetColorAt( aShaderPos + SFVEC2I( -npw, nph ) ) );
 gi += giFF( aShaderPos, ddiff4, n, shadowAt4, -npw, -nph) *
 giColorCurveShade( GetColorAt( aShaderPos + SFVEC2I( -npw,-nph ) ) );
 gi += giFF( aShaderPos, ddiff5, n, shadowAt5 , pw, nph) *
 giColorCurveShade( GetColorAt( aShaderPos + SFVEC2I( pw, nph ) ) );
 gi += giFF( aShaderPos, ddiff6, n, shadowAt6, pw,-nph) *
 giColorCurveShade( GetColorAt( aShaderPos + SFVEC2I( pw,-nph ) ) );
 gi += giFF( aShaderPos, ddiff7, n, shadowAt7, npw, ph) *
 giColorCurveShade( GetColorAt( aShaderPos + SFVEC2I( npw, ph ) ) );
 gi += giFF( aShaderPos, ddiff8, n, shadowAt8, -npw, ph) *
 giColorCurveShade( GetColorAt( aShaderPos + SFVEC2I( -npw, ph ) ) );
 }
 
 // If it received direct light, it shouldn't consider much AO
 // shadowAt0 1.0 when no shadow
 const float reduceAOwhenNoShadow = m_isUsingShadows ? ( 1.0f - shadowAt0 * 0.3f ) : 1.0f;
 
 ao = reduceAOwhenNoShadow * ( ao / ( ROUNDS * 8.0f ) );
 
 ao = ( 1.0f - 1.0f / ( ao * ao * 5.0f + 1.0f ) ) * 1.2f;
 
 gi = ( gi / ( ROUNDS * 8.0f ) );
 
 float giL = glm::min( glm::length( gi ) * 4.0f, 1.0f );
 
 giL = ( 1.0f - 1.0f / ( giL * 4.0f + 1.0f ) ) * 1.5f;
 
 return glm::mix( SFVEC3F( ao ), -gi, giL );
 }
 else
 {
 return SFVEC3F( 0.0f );
 }
}
 
 
SFVEC4F POST_SHADER_SSAO::ApplyShadeColor( const SFVEC2I& aShaderPos, const SFVEC4F& aInputColor,
 const SFVEC3F& aShadeColor ) const
{
 SFVEC4F outColor;
 SFVEC3F inColor( aInputColor );
 
 const SFVEC3F subtracted = inColor - aShadeColor;
 const SFVEC3F mixed = glm::mix( inColor, inColor * 0.50f - aShadeColor * 0.05f,
 glm::min( aShadeColor, 1.0f ) );
 
 outColor.r = ( aShadeColor.r < 0.0f ) ? subtracted.r : mixed.r;
 outColor.g = ( aShadeColor.g < 0.0f ) ? subtracted.g : mixed.g;
 outColor.b = ( aShadeColor.b < 0.0f ) ? subtracted.b : mixed.b;
 outColor.a = std::max( aInputColor.a, ( aShadeColor.r + aShadeColor.g + aShadeColor.b ) / 3 );
 
 return outColor;
}
 
 
SFVEC3F POST_SHADER_SSAO::giColorCurve( const SFVEC3F& aColor ) const
{
 const SFVEC3F vec1 = SFVEC3F( 1.0f );
 
 // This option actually apply a gamma since we are using linear color space
 // and the result shader will be applied after convert back to sRGB
 
 // http://fooplot.com/#W3sidHlwZSI6MCwiZXEiOiIxLjAtKDEuMC8oeCo5LjArMS4wKSkreCowLjEiLCJjb2xvciI6IiMwMDAwMDAifSx7InR5cGUiOjEwMDAsIndpbmRvdyI6WyItMC4wNjIxODQ2MTUzODQ2MTU1MDUiLCIxLjE0Mjk4NDYxNTM4NDYxNDYiLCItMC4xMjcwOTk5OTk5OTk5OTk3NyIsIjEuMTMyNiJdfV0-
 return vec1 - ( vec1 / (aColor * SFVEC3F(9.0f) + vec1) ) + aColor * SFVEC3F(0.10f);
}
 
 
SFVEC4F POST_SHADER_SSAO::giColorCurve( const SFVEC4F& aColor ) const
{
 return SFVEC4F( giColorCurve( SFVEC3F( aColor ) ), aColor.a );
}
 
 
SFVEC3F POST_SHADER_SSAO::giColorCurveShade( const SFVEC4F& aColor ) const
{
 return giColorCurve( SFVEC3F( aColor ) );
}
 
 
SFVEC3F POST_SHADER_SSAO::Blur( const SFVEC2I& aShaderPos ) const
{
 const float dCenter = GetDepthAt( aShaderPos );
 
 SFVEC3F shadedOut = SFVEC3F( 0.0f );
 
 float totalWeight = 1.0f;
 
 for( int y = -3; y < 3; y++ )
 {
 for( int x = -3; x < 3; x++ )
 {
 
 const unsigned int idx = GetIndex( SFVEC2I( aShaderPos.x + x, aShaderPos.y + y ) );
 
 const SFVEC3F s = m_shadedBuffer[idx];
 
 if( !( ( x == 0 ) && ( y == 0 ) ) )
 {
 
 const float d = GetDepthAt( SFVEC2I( aShaderPos.x + x, aShaderPos.y + y ) );
 
 // Increasing the value will get more sharpness effect.
 const float depthAtt = ( dCenter - d ) * dCenter * 25.0f;
 
 const float depthAttSqr = depthAtt * depthAtt;
 
 float weight = ( 1.0f / ( depthAttSqr + 1.0f ) ) - 0.02f * depthAttSqr;
 
 weight = glm::max( weight, 0.0f );
 
 shadedOut += s * weight;
 totalWeight += weight;
 }
 else
 {
 shadedOut += s;
 }
 }
 }
 
 return shadedOut / totalWeight;
}