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tanshilai
07-03-2012, 07:27 PM
We have the extension GL_ARB_2_10_10_10_REV,and the Packed Vertex Data Formats as follow:
The following figure describes how these components are laid out in a 32-bit word.
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| w | z | y | x |

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If <size> is BGRA, the components are instead laid out as in the following figure



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| w | x | y | z |

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question:I don't know the mean of "If <size> is BGRA, the components are instead laid out as in the following figure

" ,and what do the <size> mean, where is it used? thanks!

Alfonse Reinheart
07-03-2012, 08:48 PM
It means the same thing it means anywhere. The specs are all very consistent about this: names in <> refer to the parameters passed to the function (usually the last function mentioned in that section). In this case, glVertexAttribPointer (http://www.opengl.org/wiki/GLAPI/glVertexAttribPointer).

The <size> parameter can be 0, 1, 2, 3, or GL_BGRA. Yes, I know it's a GLuint, but they allow this special enum for this special condition. BTW, you should pretty much ignore this feature unless you're doing interoperation with D3D; that's what it's for.