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| Line 405: |
Line 405: |
| </program> | | </program> |
| </syntaxhighlight> | | </syntaxhighlight> |
|
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| ===Generate===
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|
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| Often shader effects need tangent vectors to work properly. These
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| tangent vectors, usually called tangent and binormal, are computed
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| on the CPU and given to the shader as vertex attributes. These
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| vectors are computed on demand on the geometry using the effect if
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| the 'generate' clause is present in the effect file. Exemple :
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|
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| <syntaxhighlight lang="xml">
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| <generate>
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| <tangent type="int">6</tangent>
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| <binormal type="int">7</binormal>
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| <normal type="int">8</normal>
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| </generate>
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| </syntaxhighlight>
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|
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| Valid subnodes of 'generate' are 'tangent', 'binormal' or 'normal'.
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| The integer value of these subnode is the index of the attribute
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| that will hold the value of the vec3 vector.
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|
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| The generate clause is located under PropertyList in the xml file.
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|
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| In order to be available for the vertex shader, these data should
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| be bound to an attribute in the program clause, like this :
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|
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| <syntaxhighlight lang="xml">
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| <program>
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| <vertex-shader>my_vertex_shader</vertex-shader>
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| <attribute>
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| <name>my_tangent_attribute</name>
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| <index>6</index>
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| </attribute>
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| <attribute>
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| <name>my_binormal_attribute</name>
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| <index>7</index>
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| </attribute>
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| </program>
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| </syntaxhighlight>
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|
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| attribute names are whatever the shader use. The index is the one
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| declared in the 'generate' clause. So because generate/tangent has
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| value 6 and my_tangent_attribute has index 6, my_tangent_attribute
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| holds the tangent value for the vertex.
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|
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|
| =Uniforms passed to shaders outside the xml effect framework= | | =Uniforms passed to shaders outside the xml effect framework= |