| 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; i<drawcount; i++) { |
| if (*(counts+i)>0) DrawArrays(mode, *(firsts+i), *(counts+i)); |
| } |
| |
| The index of the draw (<i> in the above pseudo-code) may be read by |
| a vertex shader as <gl_DrawID>. |
| |
| 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; i<drawcount; i++) { |
| if (*(counts+i)>0) { |
| DrawElements(mode, *(counts+i), type, *(indices+i)); |
| } |
| } |
| |
| The index of the draw (<i> in the above pseudo-code) may be read by |
| a vertex shader as <gl_DrawID>. |
| |
| 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; i<drawcount; i++) { |
| if (*(counts+i)>0) DrawArraysInstanced(mode, *(firsts+i), *(counts+i), |
| *(instanceCounts+1)); |
| } |
| |
| The index of the draw (<i> in the above pseudo-code) may be read by |
| a vertex shader as <gl_DrawID>. |
| |
| 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; i<drawcount; i++) { |
| if (*(counts+i)>0) { |
| DrawElementsInstanced(mode, *(counts+i), type, |
| *(indices+i), *(instanceCounts+1)); |
| } |
| } |
| |
| The index of the draw (<i> in the above pseudo-code) may be read by |
| a vertex shader as <gl_DrawID>. |
| |
| Errors |
| |
| The error INVALID_VALUE is generated by the new functions if <drawcount> |
| is less than 0. |
| |
| MultiDrawArraysANGLE, MultiDrawElementsANGLE, |
| MultiDrawArraysInstancedANGLE, and MultiDrawElementsInstancedANGLE generate |
| the same errors as DrawArrays, DrawElements, DrawArraysInstanced, |
| and DrawElementsInstanced, respectively, for any draw <i> 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 : <behavior> |
| |
| where <behavior> 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 |
