Add API to control coefficients (strength) of ambient/diffuse/specular

contributions to phong shader

python/3d/auto_generated/materials/qgsphongmaterialsettings.sip.in

@@ -72,6 +72,45 @@ Returns shininess of the surface
 Returns the opacity of the surface
 
 .. versionadded:: 3.26
+%End
+
+    float ambientCoefficient() const;
+%Docstring
+Returns the coefficient for the ambient color contribution (ie strength factor of the ambient color).
+
+.. seealso:: :py:func:`setAmbientCoefficient`
+
+.. seealso:: :py:func:`diffuseCoefficient`
+
+.. seealso:: :py:func:`specularCoefficient`
+
+.. versionadded:: 3.36
+%End
+
+    float diffuseCoefficient() const;
+%Docstring
+Returns the coefficient for the diffuse color contribution (ie strength factor of the diffuse color).
+
+.. seealso:: :py:func:`setDiffuseCoefficient`
+
+.. seealso:: :py:func:`ambientCoefficient`
+
+.. seealso:: :py:func:`specularCoefficient`
+
+.. versionadded:: 3.36
+%End
+
+    float specularCoefficient() const;
+%Docstring
+Returns the coefficient for the specular color contribution (ie strength factor of the specular color).
+
+.. seealso:: :py:func:`setSpecularCoefficient`
+
+.. seealso:: :py:func:`diffuseCoefficient`
+
+.. seealso:: :py:func:`ambientCoefficient`
+
+.. versionadded:: 3.36
 %End
 
     virtual QMap<QString, QString> toExportParameters() const;
@@ -101,7 +140,44 @@ Sets opacity of the surface
 .. versionadded:: 3.26
 %End
 
+    void setAmbientCoefficient( float coefficient );
+%Docstring
+Sets the ``coefficient`` for the ambient color contribution (ie strength factor of the ambient color).
 
+.. seealso:: :py:func:`ambientCoefficient`
+
+.. seealso:: :py:func:`setDiffuseCoefficient`
+
+.. seealso:: :py:func:`setSpecularCoefficient`
+
+.. versionadded:: 3.36
+%End
+
+    void setDiffuseCoefficient( float coefficient );
+%Docstring
+Sets the ``coefficient`` for the diffuse color contribution (ie strength factor of the diffuse color).
+
+.. seealso:: :py:func:`diffuseCoefficient`
+
+.. seealso:: :py:func:`setAmbientCoefficient`
+
+.. seealso:: :py:func:`setSpecularCoefficient`
+
+.. versionadded:: 3.36
+%End
+
+    void setSpecularCoefficient( float coefficient );
+%Docstring
+Sets the ``coefficient`` for the specular color contribution (ie strength factor of the specular color).
+
+.. seealso:: :py:func:`specularCoefficient`
+
+.. seealso:: :py:func:`setDiffuseCoefficient`
+
+.. seealso:: :py:func:`setAmbientCoefficient`
+
+.. versionadded:: 3.36
+%End
 
     virtual void readXml( const QDomElement &elem, const QgsReadWriteContext &context );
 

python/PyQt6/3d/auto_generated/materials/qgsphongmaterialsettings.sip.in

@@ -72,6 +72,45 @@ Returns shininess of the surface
 Returns the opacity of the surface
 
 .. versionadded:: 3.26
+%End
+
+    float ambientCoefficient() const;
+%Docstring
+Returns the coefficient for the ambient color contribution (ie strength factor of the ambient color).
+
+.. seealso:: :py:func:`setAmbientCoefficient`
+
+.. seealso:: :py:func:`diffuseCoefficient`
+
+.. seealso:: :py:func:`specularCoefficient`
+
+.. versionadded:: 3.36
+%End
+
+    float diffuseCoefficient() const;
+%Docstring
+Returns the coefficient for the diffuse color contribution (ie strength factor of the diffuse color).
+
+.. seealso:: :py:func:`setDiffuseCoefficient`
+
+.. seealso:: :py:func:`ambientCoefficient`
+
+.. seealso:: :py:func:`specularCoefficient`
+
+.. versionadded:: 3.36
+%End
+
+    float specularCoefficient() const;
+%Docstring
+Returns the coefficient for the specular color contribution (ie strength factor of the specular color).
+
+.. seealso:: :py:func:`setSpecularCoefficient`
+
+.. seealso:: :py:func:`diffuseCoefficient`
+
+.. seealso:: :py:func:`ambientCoefficient`
+
+.. versionadded:: 3.36
 %End
 
     virtual QMap<QString, QString> toExportParameters() const;
@@ -101,7 +140,44 @@ Sets opacity of the surface
 .. versionadded:: 3.26
 %End
 
+    void setAmbientCoefficient( float coefficient );
+%Docstring
+Sets the ``coefficient`` for the ambient color contribution (ie strength factor of the ambient color).
 
+.. seealso:: :py:func:`ambientCoefficient`
+
+.. seealso:: :py:func:`setDiffuseCoefficient`
+
+.. seealso:: :py:func:`setSpecularCoefficient`
+
+.. versionadded:: 3.36
+%End
+
+    void setDiffuseCoefficient( float coefficient );
+%Docstring
+Sets the ``coefficient`` for the diffuse color contribution (ie strength factor of the diffuse color).
+
+.. seealso:: :py:func:`diffuseCoefficient`
+
+.. seealso:: :py:func:`setAmbientCoefficient`
+
+.. seealso:: :py:func:`setSpecularCoefficient`
+
+.. versionadded:: 3.36
+%End
+
+    void setSpecularCoefficient( float coefficient );
+%Docstring
+Sets the ``coefficient`` for the specular color contribution (ie strength factor of the specular color).
+
+.. seealso:: :py:func:`specularCoefficient`
+
+.. seealso:: :py:func:`setDiffuseCoefficient`
+
+.. seealso:: :py:func:`setAmbientCoefficient`
+
+.. versionadded:: 3.36
+%End
 
     virtual void readXml( const QDomElement &elem, const QgsReadWriteContext &context );
 

src/3d/materials/qgsphongmaterialsettings.cpp

@@ -83,6 +83,9 @@ void QgsPhongMaterialSettings::readXml( const QDomElement &elem, const QgsReadWr
   mSpecular = QgsColorUtils::colorFromString( elem.attribute( QStringLiteral( "specular" ), QStringLiteral( "255,255,255" ) ) );
   mShininess = elem.attribute( QStringLiteral( "shininess" ) ).toFloat();
   mOpacity = elem.attribute( QStringLiteral( "opacity" ), QStringLiteral( "1.0" ) ).toFloat();
+  mAmbientCoefficient = elem.attribute( QStringLiteral( "ka" ), QStringLiteral( "1.0" ) ).toFloat();
+  mDiffuseCoefficient = elem.attribute( QStringLiteral( "kd" ), QStringLiteral( "1.0" ) ).toFloat();
+  mSpecularCoefficient = elem.attribute( QStringLiteral( "ks" ), QStringLiteral( "1.0" ) ).toFloat();
 
   QgsAbstractMaterialSettings::readXml( elem, context );
 }
@@ -94,6 +97,9 @@ void QgsPhongMaterialSettings::writeXml( QDomElement &elem, const QgsReadWriteCo
   elem.setAttribute( QStringLiteral( "specular" ), QgsColorUtils::colorToString( mSpecular ) );
   elem.setAttribute( QStringLiteral( "shininess" ), mShininess );
   elem.setAttribute( QStringLiteral( "opacity" ), mOpacity );
+  elem.setAttribute( QStringLiteral( "ka" ), mAmbientCoefficient );
+  elem.setAttribute( QStringLiteral( "kd" ), mDiffuseCoefficient );
+  elem.setAttribute( QStringLiteral( "ks" ), mSpecularCoefficient );
 
   QgsAbstractMaterialSettings::writeXml( elem, context );
 }
@@ -139,12 +145,18 @@ void QgsPhongMaterialSettings::addParametersToEffect( Qt3DRender::QEffect *effec
   Qt3DRender::QParameter *specularParameter = new Qt3DRender::QParameter( QStringLiteral( "specularColor" ), mSpecular );
   Qt3DRender::QParameter *shininessParameter = new Qt3DRender::QParameter( QStringLiteral( "shininess" ), mShininess );
   Qt3DRender::QParameter *opacityParameter = new Qt3DRender::QParameter( QStringLiteral( "opacity" ), mOpacity );
+  Qt3DRender::QParameter *kaParameter = new Qt3DRender::QParameter( QStringLiteral( "ka" ), mAmbientCoefficient );
+  Qt3DRender::QParameter *kdParameter = new Qt3DRender::QParameter( QStringLiteral( "kd" ), mDiffuseCoefficient );
+  Qt3DRender::QParameter *ksParameter = new Qt3DRender::QParameter( QStringLiteral( "ks" ), mSpecularCoefficient );
 
   effect->addParameter( ambientParameter );
   effect->addParameter( diffuseParameter );
   effect->addParameter( specularParameter );
   effect->addParameter( shininessParameter );
   effect->addParameter( opacityParameter );
+  effect->addParameter( kaParameter );
+  effect->addParameter( kdParameter );
+  effect->addParameter( ksParameter );
 }
 
 QByteArray QgsPhongMaterialSettings::dataDefinedVertexColorsAsByte( const QgsExpressionContext &expressionContext ) const
@@ -247,6 +259,9 @@ Qt3DRender::QMaterial *QgsPhongMaterialSettings::constantColorMaterial( const Qg
   eff->addParameter( new Qt3DRender::QParameter( QStringLiteral( "ambientColor" ), context.isSelected() ? context.selectionColor().darker() : mAmbient ) );
   eff->addParameter( new Qt3DRender::QParameter( QStringLiteral( "diffuseColor" ), context.isSelected() ? context.selectionColor() : mDiffuse ) );
   eff->addParameter( new Qt3DRender::QParameter( QStringLiteral( "specularColor" ), mSpecular ) );
+  eff->addParameter( new Qt3DRender::QParameter( QStringLiteral( "ka" ), mAmbientCoefficient ) );
+  eff->addParameter( new Qt3DRender::QParameter( QStringLiteral( "kd" ), mDiffuseCoefficient ) );
+  eff->addParameter( new Qt3DRender::QParameter( QStringLiteral( "ks" ), mSpecularCoefficient ) );
 
   if ( mOpacity < 1.0f )
   {
@@ -300,6 +315,9 @@ Qt3DRender::QMaterial *QgsPhongMaterialSettings::dataDefinedMaterial() const
 
   eff->addParameter( new Qt3DRender::QParameter( QStringLiteral( "shininess" ), mShininess ) );
   eff->addParameter( new Qt3DRender::QParameter( QStringLiteral( "opacity" ), mOpacity ) );
+  eff->addParameter( new Qt3DRender::QParameter( QStringLiteral( "ka" ), mAmbientCoefficient ) );
+  eff->addParameter( new Qt3DRender::QParameter( QStringLiteral( "kd" ), mDiffuseCoefficient ) );
+  eff->addParameter( new Qt3DRender::QParameter( QStringLiteral( "ks" ), mSpecularCoefficient ) );
 
   if ( mOpacity < 1.0f )
   {

src/3d/materials/qgsphongmaterialsettings.h

@@ -71,6 +71,39 @@ class _3D_EXPORT QgsPhongMaterialSettings : public QgsAbstractMaterialSettings
      */
     float opacity() const { return mOpacity; }
 
+    /**
+     * Returns the coefficient for the ambient color contribution (ie strength factor of the ambient color).
+     *
+     * \see setAmbientCoefficient()
+     * \see diffuseCoefficient()
+     * \see specularCoefficient()
+     *
+     * \since QGIS 3.36
+     */
+    float ambientCoefficient() const { return mAmbientCoefficient; }
+
+    /**
+     * Returns the coefficient for the diffuse color contribution (ie strength factor of the diffuse color).
+     *
+     * \see setDiffuseCoefficient()
+     * \see ambientCoefficient()
+     * \see specularCoefficient()
+     *
+     * \since QGIS 3.36
+     */
+    float diffuseCoefficient() const { return mDiffuseCoefficient; }
+
+    /**
+     * Returns the coefficient for the specular color contribution (ie strength factor of the specular color).
+     *
+     * \see setSpecularCoefficient()
+     * \see diffuseCoefficient()
+     * \see ambientCoefficient()
+     *
+     * \since QGIS 3.36
+     */
+    float specularCoefficient() const { return mSpecularCoefficient; }
+
     QMap<QString, QString> toExportParameters() const override;
 
     //! Sets ambient color component
@@ -88,7 +121,38 @@ class _3D_EXPORT QgsPhongMaterialSettings : public QgsAbstractMaterialSettings
      */
     void setOpacity( float opacity ) { mOpacity = opacity; }
 
+    /**
+     * Sets the \a coefficient for the ambient color contribution (ie strength factor of the ambient color).
+     *
+     * \see ambientCoefficient()
+     * \see setDiffuseCoefficient()
+     * \see setSpecularCoefficient()
+     *
+     * \since QGIS 3.36
+     */
+    void setAmbientCoefficient( float coefficient ) { mAmbientCoefficient = coefficient; }
 
+    /**
+     * Sets the \a coefficient for the diffuse color contribution (ie strength factor of the diffuse color).
+     *
+     * \see diffuseCoefficient()
+     * \see setAmbientCoefficient()
+     * \see setSpecularCoefficient()
+     *
+     * \since QGIS 3.36
+     */
+    void setDiffuseCoefficient( float coefficient ) { mDiffuseCoefficient = coefficient; }
+
+    /**
+     * Sets the \a coefficient for the specular color contribution (ie strength factor of the specular color).
+     *
+     * \see specularCoefficient()
+     * \see setDiffuseCoefficient()
+     * \see setAmbientCoefficient()
+     *
+     * \since QGIS 3.36
+     */
+    void setSpecularCoefficient( float coefficient ) { mSpecularCoefficient = coefficient; }
 
     void readXml( const QDomElement &elem, const QgsReadWriteContext &context ) override;
     void writeXml( QDomElement &elem, const QgsReadWriteContext &context ) const override;
@@ -113,7 +177,10 @@ class _3D_EXPORT QgsPhongMaterialSettings : public QgsAbstractMaterialSettings
              mDiffuse == other.mDiffuse &&
              mOpacity == other.mOpacity &&
              mSpecular == other.mSpecular &&
-             mShininess == other.mShininess;
+             mShininess == other.mShininess &&
+             mAmbientCoefficient == other.mAmbientCoefficient &&
+             mDiffuseCoefficient == other.mDiffuseCoefficient &&
+             mSpecularCoefficient == other.mSpecularCoefficient;
     }
 
   private:
@@ -121,6 +188,11 @@ class _3D_EXPORT QgsPhongMaterialSettings : public QgsAbstractMaterialSettings
     QColor mDiffuse{ QColor::fromRgbF( 0.7f, 0.7f, 0.7f, 1.0f ) };
     QColor mSpecular{ QColor::fromRgbF( 1.0f, 1.0f, 1.0f, 1.0f ) };
     float mShininess = 0.0f;
+
+    float mAmbientCoefficient = 1.0f;
+    float mDiffuseCoefficient = 1.0f;
+    float mSpecularCoefficient = 1.0f;
+
     float mOpacity = 1.0f;
 
     //! Constructs a material from shader files

src/3d/shaders/diffuseSpecular.frag

@@ -21,5 +21,6 @@ void main(void)
     vec3 worldView = normalize(eyePosition - worldPosition);
     fragColor = phongFunction(ambientColor, diffuseTextureColor, specularColor,
                               shininess,
+                              1.0, 1.0, 1.0,
                               worldPosition, worldView, worldNormal);
 }

src/3d/shaders/phong.inc.frag

@@ -6,6 +6,9 @@ vec4 phongFunction(const in vec4 ambient,
                    const in vec4 diffuse,
                    const in vec4 specular,
                    const in float shin,
+                   const in float ka,
+                   const in float kd,
+                   const in float ks,
                    const in vec3 worldPosition,
                    const in vec3 worldView,
                    const in vec3 worldNormal)
@@ -15,9 +18,9 @@ vec4 phongFunction(const in vec4 ambient,
     adsModel(worldPosition, worldNormal, worldView, shin, diffuseColor, specularColor);
 
     // Combine spec with ambient+diffuse for final fragment color
-    vec3 color = ambient.rgb
+    vec3 color = ka * ambient.rgb
-               + diffuseColor * diffuse.rgb
+               + kd * diffuseColor * diffuse.rgb
-               + specularColor * specular.rgb;
+               + ks * specularColor * specular.rgb;
 
     return vec4(color, diffuse.a);
 }

src/3d/shaders/phongConstant.frag

@@ -7,6 +7,9 @@ in vec3 worldNormal;
 
 uniform float shininess;
 uniform float opacity;
+uniform float ka;
+uniform float kd;
+uniform float ks;
 uniform vec3 ambientColor;
 uniform vec3 diffuseColor;
 uniform vec3 specularColor;
@@ -23,6 +26,7 @@ void main(void)
                     vec4(diffuseColor, opacity),
                     vec4(specularColor, opacity),
                     shininess,
+                    ka, kd, ks,
                     worldPosition,
                     worldView,
                     worldNormal);

src/3d/shaders/phongDataDefined.frag

@@ -2,6 +2,9 @@
 
 uniform vec3 eyePosition;
 uniform float shininess;
+uniform float ka;
+uniform float kd;
+uniform float ks;
 
 in vec3 worldPosition;
 in vec3 worldNormal;
@@ -19,5 +22,13 @@ out vec4 fragColor;
 void main(void)
 {
     vec3 worldView = normalize(eyePosition - worldPosition);
-    fragColor = phongFunction(vs_in.ambient,vs_in.diffuse,vs_in.specular, shininess, worldPosition, worldView, worldNormal);
+    fragColor = phongFunction(
+                    vs_in.ambient,
+                    vs_in.diffuse,
+                    vs_in.specular,
+                    shininess,
+                    ka, kd, ks,
+                    worldPosition,
+                    worldView,
+                    worldNormal);
 }

tests/src/3d/testqgs3drendering.cpp

@@ -75,6 +75,7 @@ class TestQgs3DRendering : public QgsTest
     void testTerrainShading();
     void testEpsg4978LineRendering();
     void testExtrudedPolygons();
+    void testPhongShading();
     void testExtrudedPolygonsDataDefined();
     void testExtrudedPolygonsGoochShading();
     void testExtrudedPolygonsMetalRoughShading();
@@ -452,6 +453,55 @@ void TestQgs3DRendering::testExtrudedPolygons()
   QGSVERIFYIMAGECHECK( "polygon3d_extrusion_opacity", "polygon3d_extrusion_opacity", img2, QString(), 40, QSize( 0, 0 ), 2 );
 }
 
+void TestQgs3DRendering::testPhongShading()
+{
+  const QgsRectangle fullExtent = mLayerDtm->extent();
+
+  std::unique_ptr< QgsVectorLayer > buildings = std::make_unique< QgsVectorLayer >( testDataPath( "/3d/buildings.shp" ), "buildings", "ogr" );
+  QVERIFY( buildings->isValid() );
+
+  QgsPhongMaterialSettings materialSettings;
+  materialSettings.setAmbient( QColor( 0, 100, 0 ) );
+  materialSettings.setDiffuse( QColor( 255, 0, 255 ) );
+  materialSettings.setSpecular( QColor( 0, 255, 255 ) );
+  materialSettings.setShininess( 2 );
+  materialSettings.setAmbientCoefficient( 0.3 );
+  materialSettings.setDiffuseCoefficient( 0.8 );
+  materialSettings.setSpecularCoefficient( 0.7 );
+  QgsPolygon3DSymbol *symbol3d = new QgsPolygon3DSymbol;
+  symbol3d->setMaterialSettings( materialSettings.clone() );
+  symbol3d->setExtrusionHeight( 10.f );
+  QgsVectorLayer3DRenderer *renderer3d = new QgsVectorLayer3DRenderer( symbol3d );
+  buildings->setRenderer3D( renderer3d );
+
+  Qgs3DMapSettings *map = new Qgs3DMapSettings;
+  map->setCrs( mProject->crs() );
+  map->setExtent( fullExtent );
+  map->setLayers( QList<QgsMapLayer *>() << buildings.get() );
+  QgsPointLightSettings defaultLight;
+  defaultLight.setIntensity( 0.5 );
+  defaultLight.setPosition( QgsVector3D( 0, 1000, 0 ) );
+  map->setLightSources( {defaultLight.clone() } );
+
+  QgsFlatTerrainGenerator *flatTerrain = new QgsFlatTerrainGenerator;
+  flatTerrain->setCrs( map->crs() );
+  map->setTerrainGenerator( flatTerrain );
+
+  QgsOffscreen3DEngine engine;
+  Qgs3DMapScene *scene = new Qgs3DMapScene( *map, &engine );
+  engine.setRootEntity( scene );
+
+  scene->cameraController()->setLookingAtPoint( QgsVector3D( 0, 0, 250 ), 300, 45, 0 );
+
+  // When running the test on Travis, it would initially return empty rendered image.
+  // Capturing the initial image and throwing it away fixes that. Hopefully we will
+  // find a better fix in the future.
+  Qgs3DUtils::captureSceneImage( engine, scene );
+  QImage img = Qgs3DUtils::captureSceneImage( engine, scene );
+
+  QGSVERIFYIMAGECHECK( "phong_shading", "phong_shading", img, QString(), 40, QSize( 0, 0 ), 2 );
+}
+
 void TestQgs3DRendering::testExtrudedPolygonsDataDefined()
 {
   QgsPropertyCollection propertyColection;