Implement GL_ANGLE_multi_draw

This patch adds entrypoints glMultiDrawArraysANGLE,
glMultiDrawElementsANGLE, glMultiDrawArraysInstancedANGLE,
annd glMultiDrawElementsInstancedANGLE

Bug: chromium:890539

Change-Id: Ic9c374c53892460f44ca6e73a253b78473ac2dff
Reviewed-on: https://chromium-review.googlesource.com/c/1282268
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>

1 files changed, 228 insertions, 0 deletions

diff --git a/extensions/ANGLE_multi_draw.txt b/extensions/ANGLE_multi_draw.txt
new file mode 100644
index 0000000000..c71996cd07
--- /dev/null
+++ b/extensions/ANGLE_multi_draw.txt
@@ -0,0 +1,228 @@
+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 extension 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 GLsizei* offsets,
+                                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 GLsizei* offsets,
+                                         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,
+                GLsizei* offsets,
+                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,
+                (const void*)(long)(*(offsets+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,
+                GLsizei* offsets,
+                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,
+                (const void*)(long)(*(offsets+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 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 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