GLAPI/glTransformFeedbackVaryings: Difference between revisions
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: An array of {{param|count}} zero-terminated strings specifying the names of the varying variables to use for transform feedback. | : An array of {{param|count}} zero-terminated strings specifying the names of the varying variables to use for transform feedback. | ||
; bufferMode | ; bufferMode | ||
: Identifies the mode used to capture the varying variables when transform feedback is active. {{param|bufferMode}} must be {{ | : Identifies the mode used to capture the varying variables when transform feedback is active. {{param|bufferMode}} must be {{enum|GL_INTERLEAVED_ATTRIBS}} or {{enum|GL_SEPARATE_ATTRIBS}}. | ||
== Description == | == Description == | ||
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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 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 {{apifunc|glLinkProgram}} is called on {{param|program}}. When {{apifunc|glLinkProgram}} is called, {{param|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 {{param|bufferMode}} is {{ | The state set by '''glTranformFeedbackVaryings''' is stored and takes effect next time {{apifunc|glLinkProgram}} is called on {{param|program}}. When {{apifunc|glLinkProgram}} is called, {{param|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 {{param|bufferMode}} is {{enum|GL_INTERLEAVED_ATTRIBS}} or multiple buffer objects if {{param|bufferMode}} is {{enum|GL_SEPARATE_ATTRIBS}}. | ||
In addition to the errors generated by '''glTransformFeedbackVaryings''', the program {{param|program}} will fail to link if: * The count specified by '''glTransformFeedbackVaryings''' is non-zero, but the program object has no vertex or geometry shader. | In addition to the errors generated by '''glTransformFeedbackVaryings''', the program {{param|program}} will fail to link if: * The count specified by '''glTransformFeedbackVaryings''' is non-zero, but the program object has no vertex or geometry shader. | ||
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* Any two entries in the {{param|varyings}} array specify the same varying variable. | * Any two entries in the {{param|varyings}} array specify the same varying variable. | ||
* The total number of components to capture in any varying variable in {{param|varyings}} is greater than the constant {{ | * The total number of components to capture in any varying variable in {{param|varyings}} is greater than the constant {{enum|GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_COMPONENTS}} and the buffer mode is {{enum|GL_SEPARATE_ATTRIBS}}. | ||
* The total number of components to capture is greater than the constant {{ | * The total number of components to capture is greater than the constant {{enum|GL_MAX_TRANSFORM_FEEDBACK_INTERLEAVED_COMPONENTS}} and the buffer mode is {{enum|GL_INTERLEAVED_ATTRIBS}}. | ||
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== Errors == | == Errors == | ||
{{ | {{enum|GL_INVALID_VALUE}} is generated if {{param|program}} is not the name of a program object. | ||
{{ | {{enum|GL_INVALID_VALUE}} is generated if {{param|bufferMode}} is {{enum|GL_SEPARATE_ATTRIBS}} and {{param|count}} is greater than the implementation-dependent limit {{enum|GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_ATTRIBS}}. | ||
== Associated Gets == | == Associated Gets == | ||
Revision as of 17:29, 29 April 2012
| Core in version | 4.6 | |
|---|---|---|
| Core since version | 3.0 | |
glTransformFeedbackVaryings: specify values to record in transform feedback buffers
Function Definition
void glTransformFeedbackVaryings(GLuintprogram, GLsizeicount, const char **varyings, GLenumbufferMode);
- 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.
Description
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.
Notes
glGetTransformFeedbackVarying is available only if the GL version is 3.0 or greater.
Errors
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.
Associated Gets
See Also
glBeginTransformFeedback, glEndTransformFeedback, glGetTransformFeedbackVarying
Copyright
Copyright © 2010 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. http://opencontent.org/openpub/.