glPatchParameter

glPatchParameter specifies the parameters that will be used for patch primitives. pname specifies the parameter to modify and must be either GL_PATCH_VERTICES , GL_PATCH_DEFAULT_OUTER_LEVEL or GL_PATCH_DEFAULT_INNER_LEVEL . For glPatchParameteri , value specifies the new value for the parameter specified by pname . For glPatchParameterfv , values specifies the address of an array containing the new values for the parameter specified by pname .

When pname is GL_PATCH_VERTICES , value specifies the number of vertices that will be used to make up a single patch primitive. Patch primitives are consumed by the tessellation control shader (if present) and subsequently used for tessellation. When primitives are specified using glDrawArrays or a similar function, each patch will be made from parameter control points, each represented by a vertex taken from the enabeld vertex arrays. parameter must be greater than zero, and less than or equal to the value of GL_MAX_PATCH_VERTICES .

When pname is GL_PATCH_DEFAULT_OUTER_LEVEL or GL_PATCH_DEFAULT_INNER_LEVEL , values contains the address of an array contiaining the default outer or inner tessellation levels, respectively, to be used when no tessellation control shader is present.

GL_INVALID_ENUM is generated if pname is not an accepted value.

GL_INVALID_VALUE is generated if pname is GL_PATCH_VERTICES and value is less than or equal to zero, or greater than the value of GL_MAX_PATCH_VERTICES .

glDrawArrays , glDrawArraysInstanced , glDrawElements , glDrawRangeElements ,

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