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The RenderMan Interface - Paul Bourke

The RenderMan Interface - Paul Bourke

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Name Type Description<br />

”blur” varying float Specifies an additional area to be added to the texture area<br />

filtered in both the s and t directions, expressed in units of<br />

texture coordinates. A value of 1.0 would request that the<br />

entire texture file be blurred into the result. A value of<br />

0.001 would request that one extra texture pixel be added<br />

in the case of a one-thousand by one-thousand texture file.<br />

”sblur” varying float Specifies ”blur” individually in the s direction.<br />

”tblur” varying float Specifies ”blur” individually in the t direction.<br />

”width” uniform float This value multiplies the width of the area being filtered<br />

over in both the s and t directions. A value of 0 effectively<br />

turns off texture antialiasing. <strong>The</strong> default value is 1.0.<br />

”swidth” uniform float Specifies ”width” individually in the s direction.<br />

”twidth” uniform float Specifies ”width” individually in the t direction.<br />

”samples” uniform float <strong>The</strong> effective sampling rate when filtering.<br />

”bias” varying float Specifies an additional bias to add to shadow depth<br />

lookups in order to prevent incorrect self-shadowing of<br />

objects.<br />

”filter” uniform string Specifies the name of the filter to use for performing the<br />

percentage-closer filtering over an area of the shadow<br />

map. <strong>The</strong> default is ”box”. Individual implementations<br />

may allow additional filters.<br />

Table 15.2: Shadow Map Access Parameters<br />

Name Type Description<br />

”resolution” uniform float [2] <strong>The</strong> highest resolution of the texture map.<br />

”type” uniform string Returns the type of the texture map file: ”texture”,<br />

”shadow”, or ”environment”.<br />

”channels” uniform float <strong>The</strong> number of channels in the map.<br />

”viewingmatrix” uniform matrix Returns a matrix that transforms points from<br />

”current” space to the ”camera” space from<br />

which the texture was created. (*).<br />

”projectionmatrix” uniform matrix Returns a matrix that transforms points from<br />

”current” space to a 2D coordinate system<br />

where x and y range from -1 to 1. (*)<br />

(*) ”viewingmatrix” and ”projectionmatrix” are only available for shadow maps or other textures<br />

that were created by rendering an image, and assume a common world-space of all<br />

cameras.<br />

Table 15.3: Data names known to the textureinfo function.<br />

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