This patch intends to implement all built-in constants, variables and
functions defined in OpenGL ES 3.1 extension GL_OES_geometry_shader
in ANGLE GLSL compiler.
1. Add all built-in constants defined in GL_OES_geometry_shader.
2. Add built-in functions EmitVertex() and EndPrimitive() required
in Geometry Shader.
3. Add built-in variables gl_PrimitiveIDIn and gl_InvocationID to
Geometry Shader.
4. Add built-in variables gl_PrimitiveID and gl_Layer to both
Geometry Shader and Fragment Shader when GL_OES_geometry_shader
is enabled.
BUG=angleproject:1941
TEST=angle_unittests
Change-Id: I92821553ed0efee2ccb77fead6e065e7799819d0
Reviewed-on: https://chromium-review.googlesource.com/627670
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
