This node defines the current bump mapping properties for all subsequent shapes. However, currently, only SoFaceSet, SoQuadMesh, and SoTriangleStripSet support bump mapping. Two categories of properties can be defined:

• Texture properties

• Appearance properties

Texture Properties: The format of the bump map texture stored within the SoTexture2 is given by the textureFormat field. The SoTextureUnit.mappingMethod field indicates if the texture stored within SoTexture2 node is a bump map texture or not. This texture can be a "height map", which is a grayscale texture of height (TextureFormat.HEIGHT_MAP), or a "normal map", which is a 3-component texture of normals (TextureFormat.NORMAL_MAP) with x, y, and z corresponding to the red, green, and blue components respectively.

If the current SoTexture2 node does not contain a 3-component texture, specifying normal map format will have no bump mapping effect.

For a height map format, only the first component of each pixel is used. A height map texture is converted internally to a normal map.

Each normal in the normal map texture can be expressed either in the space of the object called "modeling space" or in the space of the face called "tangent space". The normalMapSpace field allows you to specify the desired coordinate system. The tangent space coordinate system is convenient for applying repetitive wrinkle patterns.

Appearance Properties: OpenGL Gouraud lighting is deactivated when a shape is rendered using the bump mapping technique. A pixel shader and a vertex shader are used instead for computing the lighting contribution per pixel according to the normals stored in the normal map.

Depending on the hardware capabilities, the number of passes (maximum 3) necessary to render a shape also depends on the number of lights, brightness of the shape, and texturing (or not) of the shape. In order to select a compromise between rendering quality and rendering performance, several fields are available:

• isOnlyClosestLightUsed: Indicates if only the closest light to the shape is used for the lighting computation. true (default) improves performance by decreasing the number of rendering passes.

• isEyeDistanceAttenuation: Prevents a bumped face from smoothing with camera distance. Setting true reduces performance.

• isShadowed: Activate/deactivate the self-shadow based on the geometric normal. Setting true reduces performance.

FILE FORMAT/DEFAULT

BumpMappingProperty {

normalMapSpace	MODEL_SPACE
isShadowed	false
isEyeDistanceAttenuation	false
isOnlyClosestLightUsed	true
textureFormat	NORMAL_MAP

}

ACTION BEHAVIOR

SoGLRenderAction, SoCallbackAction Sets the current properties linked to the bump mapping. Sets: SoBumpMappingPropertyElement

Reference