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60 lines
1.9 KiB
60 lines
1.9 KiB
4 months ago
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.. _vertexelements:
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Vertex Elements
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===============
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This state controls the format of the input attributes contained in
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pipe_vertex_buffers. There is one pipe_vertex_element array member for each
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input attribute.
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Input Formats
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-------------
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Gallium supports a diverse range of formats for vertex data. Drivers are
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guaranteed to support 32-bit floating-point vectors of one to four components.
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Additionally, they may support the following formats:
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* Integers, signed or unsigned, normalized or non-normalized, 8, 16, or 32
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bits wide
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* Floating-point, 16, 32, or 64 bits wide
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At this time, support for varied vertex data formats is limited by driver
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deficiencies. It is planned to support a single uniform set of formats for all
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Gallium drivers at some point.
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Rather than attempt to specify every small nuance of behavior, Gallium uses a
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very simple set of rules for padding out unspecified components. If an input
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uses less than four components, it will be padded out with the constant vector
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``(0, 0, 0, 1)``.
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Fog, point size, the facing bit, and edgeflags, all are in the standard format
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of ``(x, 0, 0, 1)``, and so only the first component of those inputs is used.
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Position
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%%%%%%%%
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Vertex position may be specified with two to four components. Using less than
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two components is not allowed.
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Colors
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%%%%%%
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Colors, both front- and back-facing, may omit the alpha component, only using
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three components. Using less than three components is not allowed.
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Members
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-------
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src_offset
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The byte offset of the attribute in the buffer given by
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vertex_buffer_index for the first vertex.
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instance_divisor
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The instance data rate divisor, used for instancing.
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0 means this is per-vertex data, n means per-instance data used for
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n consecutive instances (n > 0).
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vertex_buffer_index
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The vertex buffer this attribute lives in. Several attributes may
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live in the same vertex buffer.
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src_format
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The format of the attribute data. One of the PIPE_FORMAT tokens.
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