glPatchParameteri

glPatchParameter: man4/glPatchParameter.xml

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.