qgsphongtexturedmaterialsettings.cpp

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/***************************************************************************
  qgsphongtexturedmaterialsettings.cpp
  --------------------------------------
  Date                 : August 2020
  Copyright            : (C) 2020 by Nyall Dawson
  Email                : nyall dot dawson at gmail dot com
 ***************************************************************************
 *                                                                         *
 *   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.                                   *
 *                                                                         *
 ***************************************************************************/
 
#include "qgsphongtexturedmaterialsettings.h"
 
#include "qgsapplication.h"
#include "qgscolorutils.h"
#include "qgsimagecache.h"
#include "qgsphongmaterialsettings.h"
 
#include <QImage>
#include <QMap>
#include <QString>
 
using namespace Qt::StringLiterals;
 
QString QgsPhongTexturedMaterialSettings::type() const
{
  return u"phongtextured"_s;
}
 
bool QgsPhongTexturedMaterialSettings::supportsTechnique( Qgis::MaterialRenderingTechnique technique )
{
  switch ( technique )
  {
    case Qgis::MaterialRenderingTechnique::Triangles:
    case Qgis::MaterialRenderingTechnique::TrianglesDataDefined: //technique is supported but color can't be datadefined
      return true;
 
    case Qgis::MaterialRenderingTechnique::Points:
    case Qgis::MaterialRenderingTechnique::TrianglesWithFixedTexture:
    case Qgis::MaterialRenderingTechnique::TrianglesFromModel:
    case Qgis::MaterialRenderingTechnique::InstancedPoints:
    case Qgis::MaterialRenderingTechnique::Lines:
    case Qgis::MaterialRenderingTechnique::Billboards:
      return false;
  }
  return false;
}
 
QgsAbstractMaterialSettings *QgsPhongTexturedMaterialSettings::create()
{
  return new QgsPhongTexturedMaterialSettings();
}
 
QgsPhongTexturedMaterialSettings *QgsPhongTexturedMaterialSettings::clone() const
{
  return new QgsPhongTexturedMaterialSettings( *this );
}
 
bool QgsPhongTexturedMaterialSettings::equals( const QgsAbstractMaterialSettings *other ) const
{
  const QgsPhongTexturedMaterialSettings *otherPhong = dynamic_cast<const QgsPhongTexturedMaterialSettings *>( other );
  if ( !otherPhong )
    return false;
 
  return *this == *otherPhong;
}
 
bool QgsPhongTexturedMaterialSettings::requiresTextureCoordinates() const
{
  return !mDiffuseTexturePath.isEmpty();
}
 
double QgsPhongTexturedMaterialSettings::textureRotation() const
{
  return mTextureRotation;
}
 
QColor QgsPhongTexturedMaterialSettings::averageColor() const
{
  const double avgDiffuseFactor = 0.3;
  const double avgSpecularFactor = 0.2;
 
  const double kAmbient = 0.2;
  const double kDiffuse = 0.6;
  const double kSpecular = 0.2;
 
  const QColor diffuse = textureAverageColor();
 
  double red = kAmbient * mAmbient.redF() + kDiffuse * avgDiffuseFactor * diffuse.redF() + kSpecular * avgSpecularFactor * mSpecular.redF();
 
  double green = kAmbient * mAmbient.greenF() + kDiffuse * avgDiffuseFactor * diffuse.greenF() + kSpecular * avgSpecularFactor * mSpecular.greenF();
 
  double blue = kAmbient * mAmbient.blueF() + kDiffuse * avgDiffuseFactor * diffuse.blueF() + kSpecular * avgSpecularFactor * mSpecular.blueF();
 
  red = std::clamp( red, 0.0, 1.0 );
  green = std::clamp( green, 0.0, 1.0 );
  blue = std::clamp( blue, 0.0, 1.0 );
 
  return QColor::fromRgbF( static_cast<float>( red ), static_cast<float>( green ), static_cast<float>( blue ), static_cast<float>( mOpacity ) );
}
 
 
QColor QgsPhongTexturedMaterialSettings::textureAverageColor() const
{
  if ( mTextureAverageColor.has_value() )
  {
    return *mTextureAverageColor;
  }
 
  bool fitsInCache = false;
  QImage texture = QgsApplication::imageCache()->pathAsImage( mDiffuseTexturePath, QSize(), true, 1.0, fitsInCache );
  if ( texture.isNull() )
  {
    mTextureAverageColor = QColor( 127, 127, 127 );
    return *mTextureAverageColor;
  }
 
  if ( texture.format() != QImage::Format_ARGB32 )
  {
    texture = texture.convertToFormat( QImage::Format_ARGB32 );
  }
 
  unsigned long long red = 0;
  unsigned long long green = 0;
  unsigned long long blue = 0;
  unsigned long long pixelCount = 0;
 
  // downsampling to ensure a fast computation
  const int sampleStep = std::min( texture.width() / 5, texture.height() / 5 );
  const int width = texture.width();
  const int height = texture.height();
  for ( int y = 0; y < height; y += sampleStep )
  {
    const QRgb *line = reinterpret_cast< const QRgb * >( texture.constScanLine( y ) );
    for ( int x = 0; x < width; x += sampleStep )
    {
      const QRgb pixel = line[x];
      red += qRed( pixel );
      green += qGreen( pixel );
      blue += qBlue( pixel );
      pixelCount++;
    }
  }
 
  mTextureAverageColor = QColor( static_cast<int>( red / pixelCount ), static_cast<int>( green / pixelCount ), static_cast<int>( blue / pixelCount ) );
  return *mTextureAverageColor;
}
 
void QgsPhongTexturedMaterialSettings::setColorsFromBase( const QColor &baseColor, float metallic )
{
  metallic = std::clamp( metallic, 0.0f, 1.0f );
 
  const float baseR = baseColor.redF();
  const float baseG = baseColor.greenF();
  const float baseB = baseColor.blueF();
 
  // ambient: stable, non-directional lighting
  constexpr float AMBIENT_FACTOR = 0.2f;
  mAmbient = QColor::fromRgbF( baseR * AMBIENT_FACTOR, baseG * AMBIENT_FACTOR, baseB * AMBIENT_FACTOR );
 
  // F0: Fresnel reflectance at normal incidence
  constexpr float F0_DIELECTRIC = 0.04f;
 
  // specular
  // * Non-metallic surfaces: Independent of base color
  // * Metallic surfaces:
  //   - Reflect their own color
  //   - Linear interpolation from white to base color as metallic increases
  mSpecular = QColor::fromRgbF( ( 1.0f - metallic ) * F0_DIELECTRIC + metallic * baseR, ( 1.0f - metallic ) * F0_DIELECTRIC + metallic * baseG, ( 1.0f - metallic ) * F0_DIELECTRIC + metallic * baseB );
 
  constexpr float MIN_SHININESS = 32.0f;
  constexpr float MAX_SHININESS = 200.0f;
  mShininess = MIN_SHININESS + metallic * ( MAX_SHININESS - MIN_SHININESS );
}
 
void QgsPhongTexturedMaterialSettings::setColorsFromBase( const QColor &baseColor )
{
  setColorsFromBase( baseColor, 0.0f );
}
 
void QgsPhongTexturedMaterialSettings::readXml( const QDomElement &elem, const QgsReadWriteContext &context )
{
  mAmbient = QgsColorUtils::colorFromString( elem.attribute( u"ambient"_s, u"25,25,25"_s ) );
  mSpecular = QgsColorUtils::colorFromString( elem.attribute( u"specular"_s, u"255,255,255"_s ) );
  mShininess = elem.attribute( u"shininess"_s ).toDouble();
  mOpacity = elem.attribute( u"opacity"_s, u"1.0"_s ).toDouble();
  mDiffuseTexturePath = elem.attribute( u"diffuse_texture_path"_s, QString() );
  mTextureScale = elem.attribute( u"texture_scale"_s, QString( "1.0" ) ).toDouble();
  mTextureRotation = elem.attribute( u"texture-rotation"_s, QString( "0.0" ) ).toDouble();
 
  QgsAbstractMaterialSettings::readXml( elem, context );
}
 
void QgsPhongTexturedMaterialSettings::writeXml( QDomElement &elem, const QgsReadWriteContext &context ) const
{
  elem.setAttribute( u"ambient"_s, QgsColorUtils::colorToString( mAmbient ) );
  elem.setAttribute( u"specular"_s, QgsColorUtils::colorToString( mSpecular ) );
  elem.setAttribute( u"shininess"_s, mShininess );
  elem.setAttribute( u"opacity"_s, mOpacity );
  elem.setAttribute( u"diffuse_texture_path"_s, mDiffuseTexturePath );
  elem.setAttribute( u"texture_scale"_s, mTextureScale );
  elem.setAttribute( u"texture-rotation"_s, mTextureRotation );
 
  QgsAbstractMaterialSettings::writeXml( elem, context );
}