On 08/01/2016 10:29 AM, Kenneth Graunke wrote:
> This error condition is not implementable when using tessellation or
> geometry shaders. The text was also removed from the ES 3.2 spec.
> I believe the intended behavior is to remove the error condition
> when either OES_geometry_shader or OES_tessellation_shader are
> exposed.
>
> Signed-off-by: Kenneth Graunke <kenn...@whitecape.org>
> ---
> src/mesa/main/api_validate.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/src/mesa/main/api_validate.c b/src/mesa/main/api_validate.c
> index 2ee2cd8..68f55b6 100644
> --- a/src/mesa/main/api_validate.c
> +++ b/src/mesa/main/api_validate.c
> @@ -546,8 +546,20 @@ validate_draw_arrays(struct gl_context *ctx, const char
> *func,
> *
> * This is in contrast to the behaviour of desktop GL, where the extra
> * primitives are silently dropped from the transform feedback buffer.
> + *
> + * This text is removed in ES 3.2, presumably because it's not really
> + * implementable with geometry and tessellation shaders. In fact,
> + * issue 13 of the OES_geometry_shader spec says:
> + *
> + * "Since we no longer require being able to predict how much geometry
> will
> + * be generated [...]"
> + *
> + * It isn't speaking about this condition specifically, but speaks of
> + * lifting similar transform feedback drawing restrictions.
> */
This is the spec text that I quoted in my similar patch:
+ *
+ * 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. Because dynamic geometry amplification in a geometry
+ * shader can make it difficult if not impossible to predict the amount
+ * of geometry that may be generated in advance of executing the shader,
+ * the draw-time error for transform feedback buffer overflow conditions
+ * is removed and replaced with the GL behavior (primitives are not
+ * written and the corresponding counter is not updated)...
> - if (_mesa_is_gles3(ctx) && _mesa_is_xfb_active_and_unpaused(ctx)) {
> + if (_mesa_is_gles3(ctx) && _mesa_is_xfb_active_and_unpaused(ctx) &&
> + !_mesa_has_OES_geometry_shader(ctx) &&
> + !_mesa_has_OES_tessellation_shader(ctx)) {
> size_t prim_count = vbo_count_tessellated_primitives(mode, count, 1);
> if (xfb_obj->GlesRemainingPrims < prim_count) {
> _mesa_error(ctx, GL_INVALID_OPERATION,
>
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