Name ANGLE_multi_draw Name Strings GL_ANGLE_multi_draw Contributors Austin Eng, Google Inc. Kai Ninomiya, Google Inc. Kenneth Russell, Google Inc. Contributors to the EXT_multi_draw_arrays specification Contributors to the ARB_shader_draw_parameters specification Contact Austin Eng (enga 'at' google.com) Status Incomplete Version Last Modified Date: October 24, 2018 Author Revision: 1 Number OpenGL ES Extension XX Dependencies OpenGL ES 2.0 is required. This extension is written against the OpenGL ES 2.0 specification, the OpenGL ES 3.0 specification, and the OpenGL ES Shading Language 3.0 specification. The presence of the GL_ANGLE_instanced_arrays or GL_EXT_instanced_arrays extensions affects the definition of this extension. Overview This extension exposes the Multi* draw call variants in EXT_multi_draw_arrays functionality in addition to the vertex shader builtin gl_DrawID exposed by ARB_shader_draw_parameters for OpenGL. These functions behave identically to the standard functions DrawArrays() and DrawElements() except they handle multiple lists of vertices in one call. Their main purpose is to allow one function call to render more than one primitive such as triangle strip, triangle fan, etc. Additionally, this extension adds a further built-in variable, gl_DrawID to the shading language. This variable contains the index of the draw currently being processed by a Multi* variant of a drawing command. IP Status No known IP claims. New Procedures and Functions void MultiDrawArraysANGLE(enum mode, const GLint* firsts, const GLsizei* counts, const GLsizei drawcount); void MultiDrawElementsANGLE(enum mode, const GLint* counts, GLenum type, const GLvoid* const* indices, const GLsizei drawcount); void MultiDrawArraysInstancedANGLE(enum mode, const GLint* firsts, const GLsizei* counts, const GLsizei* instanceCounts, const GLsizei drawcount); void MultiDrawElementsInstancedANGLE(enum mode, const GLint* counts, GLenum type, const GLvoid* const* indices, const GLsizei* instanceCounts, const GLsizei drawcount); New Tokens None. Additions to Chapter 2 of the OpenGL ES 2.0 Specification Section 2.8 Vertex Arrays: The command void MultiDrawArraysANGLE(GLenum mode, const GLint* firsts, const GLsizei *counts, GLsizei drawcount) Behaves identically to DrawArrays except that a list of arrays is specified instead. The number of lists is specified in the drawcount parameter. It has the same effect as: for(i=0; i0) DrawArrays(mode, *(firsts+i), *(counts+i)); } The index of the draw ( in the above pseudo-code) may be read by a vertex shader as . The command void MultiDrawElementsANGLE(GLenum mode, GLsizei* counts, GLenum type, const GLvoid* const* indices, GLsizei drawcount) Behaves identically to DrawElements except that a list of arrays is specified instead. The number of lists is specified in the drawcount parameter. It has the same effect as: for(i=0; i0) { DrawElements(mode, *(counts+i), type, *(indices+i)); } } The index of the draw ( in the above pseudo-code) may be read by a vertex shader as . Additions to Chapter 2 of the OpenGL ES 3.0 Specification Section 2.9.3 Drawing Commands: The command void MultiDrawArraysInstancedANGLE( GLenum mode, const GLint* firsts, const GLsizei *counts, const GLsizei* instanceCounts, GLsizei drawcount) Behaves identically to DrawArraysInstanced except that a list of arrays is specified instead. The number of lists is specified in the drawcount parameter. It has the same effect as: for(i=0; i0) DrawArraysInstanced(mode, *(firsts+i), *(counts+i), *(instanceCounts+1)); } The index of the draw ( in the above pseudo-code) may be read by a vertex shader as . The command void MultiDrawElementsInstancedANGLE( GLenum mode, GLsizei* counts, GLenum type, const GLvoid* const* indices, const GLsizei* instanceCounts, GLsizei drawcount) Behaves identically to DrawElementsInstanced except that a list of arrays is specified instead. The number of lists is specified in the drawcount parameter. It has the same effect as: for(i=0; i0) { DrawElementsInstanced(mode, *(counts+i), type, *(indices+i), *(instanceCounts+1)); } } The index of the draw ( in the above pseudo-code) may be read by a vertex shader as . Errors The error INVALID_VALUE is generated by the new functions if is less than 0. MultiDrawArraysANGLE, MultiDrawElementsANGLE, MultiDrawArraysInstancedANGLE, and MultiDrawElementsInstancedANGLE generate the same errors as DrawArrays, DrawElements, DrawArraysInstanced, and DrawElementsInstanced, respectively, for any draw where an error is generated. If any call would produce an error, no drawing is performed. Modifications to the OpenGL ES Shading Language Specification, Version 3.00 Including the following line in a shader can be used to control the language featured described in this extension: #extension GL_ANGLE_multi_draw : where is as specified in section 3.5. A new preprocessor #define is added to the OpenGL ES Shading Language: #define GL_ANGLE_multi_draw 1 Dependencies on GL_ANGLE_instanced_arrays If GL_ANGLE_instanced_arrays or GL_EXT_instanced_arrays is enabled, append the lanuage in "Additions to Chapter 2 of the OpenGL ES 3.0 Specification, Section 2.9.3 Drawing Commands" to the language in "Additions to Chapter 2 of the OpenGL ES 2.0 Specification, Section 2.8 Vertex Arrays". If GL_ANGLE_instanced_arrays or GL_EXT_instanced_arrays is not enabled and the context is less than a OpenGL ES 3.0 context, the error INVALID_OPERATION is generated by any call to the functions MultiDrawArraysInstancedANGLE and MultiDrawElementsInstancedANGLE. Issues None Revision History Rev. Date Author Changes ---- -------- ---------- -------------------------------------------- 1 10/24/18 Austin Eng First revision. 2 10/25/18 Austin Eng Second revision. Add instanced variants