# Multi Pass Effects in Candera > Examples for Local 3D Effect Shaders #### Description This chapter describes special 3D effect shaders techniques supported by [Candera](http://dev.doc.cgistudio.at/APILINK/namespace_candera.html "[DataBinding_RefTypeSample]"). #### **Fur** ##### Description This chapter describes how to generate the fur effect using the multipass appearance technique supported by [Candera](http://dev.doc.cgistudio.at/APILINK/namespace_candera.html "[DataBinding_RefTypeSample]"). ##### **Introduction** The fur effect is produce by rendering the node multiple times with different appearances which are blended together. Each appearance will use the same combination of noise and color map textures but with different and specific render states. For each appearance the following uniforms will have to be set specifically: [\[1\]](https://doc316en.candera.eu/link/549#bkmrk-references%C2%A0)

- u\_ColorScale - fur color scale. - u\_Scale - scale factor to manipulate vertices along normals - u\_PassIndex - render pass index

##### **Workflow** ##### Appearances Because the generation of the fur effect implies that the node has to be rendered multiple times, a special appearance needs to be used: [Candera::MultiPassAppearance](http://dev.doc.cgistudio.at/APILINK/class_candera_1_1_multi_pass_appearance.html "A MultiPassAppearance enables a node to be rendered multiple times with different appearance settings..."). The particularity of this appearance is that it keeps a pointer to the next appearance, defining so a sequence of render passes.

A nice fur effect is obtained with at least 10 render passes.

``` for (int i = 0; i<= 15; i++) { m_furAppearances[i] = MultiPassAppearance::Create(); // Configure the appearances // ... // End of appearances configuration if (i > 0) { m_furAppearances[i-1]->SetNextPass(m_furAppearances[i]); } } mesh->SetAppearance(m_furAppearances[0]); ``` ##### Shader The table below presents the vertex and fragment shader needed to generate the fur effect:

Vertex shader	RefTransFur
Fragment shader	RefUniColorTexFur

Set this shader for all the appearances: ``` m_furAppearances[i]->SetShader(m_furShader); ```

: Lighting and material has no influence on the fur effect.

##### Shader Parameters Setter Configure the uniforms setter as follows: ``` m_furSetter[i] = GenericShaderParamSetter::Create(); m_furSetter[i]->SetModelViewProjectionMatrix4Enabled(true); m_furSetter[i]->SetLightActivationEnabled(true); m_furSetter[i]->SetMaterialActivationEnabled(true); m_furSetter[i]->SetTextureActivationEnabled(true); ``` Prepare the uniforms data: ``` m_furColorScale[0] = 0.2196f; m_furColorScale[1] = 0.2202f; m_furColorScale[2] = 0.2202f; m_furColorScale[3] = 1.0f; if ( i == 0 ) { m_furScale = 1.0f; } else { m_furScale = 0.01f; } m_passIndex[i] = ((Float) i); ``` Set the uniforms using the shader parameter setter: ``` m_furSetter[i]->SetUniform("u_ColorScale",Shader::FloatVec4,m_furColorScale); m_furSetter[i]->SetUniform("u_Scale",Shader::Float,&m_furScale); m_furSetter[i]->SetUniform("u_PassIndex",Shader::Float,&m_passIndex[i]); ``` ##### Material Configuration ``` if ( i == 0) { m_furAppearances[i]->SetMaterial(Material::Create()); } else { m_furAppearances[i]->SetMaterial(m_furAppearances[0]->GetMaterial()); } ``` ##### Noise texture

Set the fur appearance noise texture: ``` m_furAppearances[i]->SetTexture(m_furNoise, 0); ``` ##### Color map texture The color map texture is meant to provide a color for the fur.

Set the fur appearance color map texture: ``` m_furAppearances[i]->SetTexture(m_furColor, 1); ``` ##### Render Mode Set and configure a Render Mode for all transparency layers (appearances 1 to 15). ``` if (i > 0) { m_furAppearances[i]->GetRenderMode()->SetBlendingEnabled(true); m_furAppearances[i]->GetRenderMode()->SetBlendMode(RenderMode::SourceAlpha, RenderMode::One, RenderMode::Add); } ``` ##### **Example** Here is exemplified the fur effect applied on sphere:

##### Fur Effect in SceneComposer To experiment with the fur effect in SceneComposer use solution **ShaderExamples** from folder *cgi\_studio\_player/content/Tutorials/04\_ShaderUsage*. ##### **References** \[1\] Image taken from [http://www.xbdev.net/directx3dx/specialX/Fur/index.php](http://www.xbdev.net/directx3dx/specialX/Fur/index.php) --- #### **Gooch Effect** ##### Description This chapter describes how to generate the Gooch effect using the multipass appearance technique supported by [Candera](http://dev.doc.cgistudio.at/APILINK/namespace_candera.html "[DataBinding_RefTypeSample]"). ##### **Introduction** ##### Gooch Effect The Gooch effect is a non photorealistic technique which simulates the appearance of technical illustration. The effect is generated in two render passes. In the first pass the object is drawn in warm - cool colors: all surfaces that are facing toward the light source are drawn in warm colors (red, yellow etc), all surfaces away from the light source are drawn in cool colors (blue, violet etc.). The second render pass draws the silhouette of the object with a fixed color (e.g. black). [\[1\]](https://doc316en.candera.eu/link/549#bkmrk-references%C2%A0-0)

##### **Workflow** ##### Inventory In order to generate the Gooch effect on a node you need:

- Two MultiPassAppearances - Specific shader for each appearance - Specific shader parameters setter for each appearance - Material - Render Modes

##### Appearances The Gooch effect is generated in two render passes so we need two MultiPassAppearances: ``` m_goochAppearance1 = MultiPassAppearance::Create(); m_goochAppearance2 = MultiPassAppearance::Create(); m_goochAppearance1->SetNextPass(m_goochAppearance2); m_mesh->SetAppearance(m_goochAppearance1); ``` ##### Shader Each appearance need a specific shader, see table below:

Appearance	Vertex shader	Fragment shader
m\_goochAppearance1	RefTransLight1Gooch	RefGoochShading
m\_goochAppearance2	RefTransScale	RefUniColor

Set the shader for each appearance: ``` m_goochAppearance1->SetShader(m_goochPass1Shader); m_goochAppearance2->SetShader(m_goochPass2Shader); ``` ##### Shader Parameter Setter The uniform setter will have to be set as follows: ``` m_goochUniformSetter1 = GenericShaderParamSetter::Create(); m_goochUniformSetter1->SetMaterialActivationEnabled(true); m_goochUniformSetter1->SetLightActivationEnabled(true); m_goochUniformSetter1->SetLightsCoordinateSpace(Light::World); m_goochUniformSetter1->SetModelViewProjectionMatrix4Enabled(true); m_goochUniformSetter1->SetModelMatrix4Enabled(true); m_goochUniformSetter1->SetNormalModelMatrix3Enabled(true); m_goochUniformSetter1->SetCameraPositionEnabled(true); m_goochAppearance1->SetShaderParamSetter(m_goochUniformSetter1); m_goochUniformSetter2 = GenericShaderParamSetter::Create(); m_goochUniformSetter2->SetModelViewProjectionMatrix4Enabled(true); m_goochAppearance2->SetShaderParamSetter(m_goochUniformSetter2); ``` Prepare uniform data: ``` m_coolDiffuseWeight= 0.25f; m_warmDiffuseWeight = 0.5f; m_goochScale = 0.1f; m_coolColor[0] = 0.0f; m_coolColor[1] = 0.0f; m_coolColor[2] = 0.55f; m_coolColor[3] = 1.0f; m_warmColor[0] = 0.3f; m_warmColor[1] = 0.3f; m_warmColor[2] = 0.0f; m_warmColor[3] = 1.0f; m_silhouetteColor[0] = 0.0f; m_silhouetteColor[1] = 0.0f; m_silhouetteColor[2] = 0.0f; m_silhouetteColor[3] = 1.0f; ``` Set the uniforms: ``` m_goochUniformSetter1->SetUniform("u_CoolDiffuseWeight", Shader::Float, &m_coolDiffuseWeight); m_goochUniformSetter1->SetUniform("u_WarmDiffuseWeight", Shader::Float, &m_warmDiffuseWeight); m_goochUniformSetter1->SetUniform("u_CoolColor", Shader::FloatVec4, m_coolColor); m_goochUniformSetter1->SetUniform("u_WarmColor", Shader::FloatVec4, m_warmColor); m_goochUniformSetter2->SetUniform("u_Scale", Shader::Float, &m_goochScale); m_goochUniformSetter2->SetUniform("u_Color", Shader::FloatVec4, m_silhouetteColor); ``` ##### Material Configuration ``` m_goochAppearance1->SetMaterial(Material::Create()); m_goochAppearance1->GetMaterial()->SetDiffuse(Color(0.75f, 0.75f, 0.75f, 1.0f)); m_goochAppearance1->GetMaterial()->SetAmbient(Color(0.0f, 0.0f, 0.0f, 0.0f)); m_goochAppearance1->GetMaterial()->SetSpecular(Color(1.0f, 1.0f, 1.0f, 1.0f)); m_goochAppearance1->GetMaterial()->SetSpecularPower(20.0f); m_goochAppearance2->SetMaterial(Material::Create()); ``` ##### Render Mode ``` m_goochAppearance1->SetRenderMode(RenderMode::Create()); m_goochAppearance1->GetRenderMode()->SetCulling(RenderMode::BackFaceCulling); m_goochAppearance2->SetRenderMode(RenderMode::Create()); m_goochAppearance2->GetRenderMode()->SetCulling(RenderMode::FrontFaceCulling); ``` ##### **Example** Here is exemplified the Gooch effect:

##### Gooch Effect in SceneComposer To experiment with the Gooch effect in SceneComposer use solution **ShaderExamples** from folder *cgi\_studio\_player/content/Tutorials/04\_ShaderUsage*.