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mesa: Document reasons for allowing XFB drawing modes in GLES 3.1 w/GL_OES_geometry_shader 

Originally this patch added the checks to allow the draw calls with XFB,
but commit 2dabd497 beat me to it.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Ian Romanick 2016-05-23 15:29:14 -07:00
parent aa228eb1a6
commit 658e90f9a8
1 changed files with 31 additions and 2 deletions
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33
src/mesa/main/api_validate.c
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@ -396,12 +396,30 @@ validate_DrawElements_common(struct gl_context *ctx,
const GLvoid *indices,
const char *caller)
{
/* From the GLES3 specification, section 2.14.2 (Transform Feedback
* Primitive Capture):
/* Section 2.14.2 (Transform Feedback Primitive Capture) of the OpenGL ES
* 3.1 spec says:
*
* The error INVALID_OPERATION is also generated by DrawElements,
* DrawElementsInstanced, and DrawRangeElements while transform feedback
* is active and not paused, regardless of mode.
*
* The OES_geometry_shader_spec says:
*
* Issues:
*
* ...
*
* (13) Does this extension change how transform feedback operates
* compared to unextended OpenGL ES 3.0 or 3.1?
*
* RESOLVED: Yes... Since we no longer require being able to predict how
* much geometry will be generated, we also lift the restriction that
* only DrawArray* commands are supported and also support the
* DrawElements* commands for transform feedback.
*
* This should also be reflected in the body of the spec, but that appears
* to have been overlooked. The body of the spec only explicitly allows
* the indirect versions.
*/
if (_mesa_is_gles3(ctx) && !ctx->Extensions.OES_geometry_shader &&
_mesa_is_xfb_active_and_unpaused(ctx)) {
@ -730,6 +748,17 @@ valid_draw_indirect(struct gl_context *ctx,
*
* "An INVALID_OPERATION error is generated if
* transform feedback is active and not paused."
*
* The OES_geometry_shader spec says:
*
* On p. 250 in the errors section for the DrawArraysIndirect command,
* and on p. 254 in the errors section for the DrawElementsIndirect
* command, delete the errors which state:
*
* "An INVALID_OPERATION error is generated if transform feedback is
* active and not paused."
*
* (thus allowing transform feedback to work with indirect draw commands).
*/
if (_mesa_is_gles31(ctx) && !ctx->Extensions.OES_geometry_shader &&
_mesa_is_xfb_active_and_unpaused(ctx)) {