glTransformFeedbackVaryings - specify values to record in transform feedback buffers

glGetTransformFeedbackVarying()

voidglTransformFeedbackVaryings(GLuintprogram,GLsizeicount,constchar**varyings,GLenumbufferMode);

       Copyright © 2010-2014 Khronos Group

[FIXME: source]                                    11/18/2024                           GLTRANSFORMFEEDBACKV(3G)

       The names of the vertex or geometry shader outputs to be recorded in transform feedback mode are
       specified using glTransformFeedbackVaryings. When a geometry shader is active, transform feedback records
       the values of selected geometry shader output variables from the emitted vertices. Otherwise, the values
       of the selected vertex shader outputs are recorded.

       The state set by glTranformFeedbackVaryings is stored and takes effect next time glLinkProgram() is
       called on program. When glLinkProgram() is called, program is linked so that the values of the specified
       varying variables for the vertices of each primitive generated by the GL are written to a single buffer
       object if bufferMode is GL_INTERLEAVED_ATTRIBS or multiple buffer objects if bufferMode is
       GL_SEPARATE_ATTRIBS.

       In addition to the errors generated by glTransformFeedbackVaryings, the program program will fail to link
       if:

       •   The count specified by glTransformFeedbackVaryings is non-zero, but the program object has no vertex
           or geometry shader.

       •   Any variable name specified in the varyings array is not declared as an output in the vertex shader
           (or the geometry shader, if active).

       •   Any two entries in the varyings array specify the same varying variable.

       •   The total number of components to capture in any varying variable in varyings is greater than the
           constant GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_COMPONENTS and the buffer mode is GL_SEPARATE_ATTRIBS.

       •   The total number of components to capture is greater than the constant
           GL_MAX_TRANSFORM_FEEDBACK_INTERLEAVED_COMPONENTS and the buffer mode is GL_INTERLEAVED_ATTRIBS.

GL_INVALID_VALUE is generated if program is not the name of a program object.

       GL_INVALID_VALUE is generated if bufferMode is GL_SEPARATE_ATTRIBS and count is greater than the
       implementation-dependent limit GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_ATTRIBS.

       glTransformFeedbackVaryings - specify values to record in transform feedback buffers

glGetTransformFeedbackVarying is available only if the GL version is 3.0 or greater.

program
           The name of the target program object.

       count
           The number of varying variables used for transform feedback.

       varyings
           An array of count zero-terminated strings specifying the names of the varying variables to use for
           transform feedback.

       bufferMode
           Identifies the mode used to capture the varying variables when transform feedback is active.
           bufferMode must be GL_INTERLEAVED_ATTRIBS or GL_SEPARATE_ATTRIBS.

glBeginTransformFeedback(),

       glEndTransformFeedback, glGetTransformFeedbackVarying()

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       │ Function                    │ 2.0 │ 2.1 │ 3.0 │ 3.1 │ 3.2 │ 3.3 │ 4.0 │ 4.1 │ 4.2 │ 4.3 │ 4.4 │ 4.5 │
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       │ Feature                     │     │     │     │     │     │     │     │     │     │     │     │     │
       │ Name                        │     │     │     │     │     │     │     │     │     │     │     │     │
       ├─────────────────────────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
       │ glTransformFeedbackVaryings │  -  │  -  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │
       └─────────────────────────────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┘