main: Allow for the possibility of GL 3.2 without ARB_geometry_shader4.

Previously, we assumed that the only way Mesa would expose geometry
shader support was via the ARB_geometry_shader4 extension.  But this
extension has some extra complications over GL 3.2 (interactions with
compatibility-only features, and link-time initialization of the
constant gl_VerticesIn).  So we want to allow for the possibility of
supporting GL 3.2 (with GLSL 1.50 style geometry shaders) even if
ctx->Extensions.ARB_geometry_shader4 is false.

This patch adds a new function, _mesa_has_geometry_shaders(), which
returns true if either ARB_geometry_shader4 is supported or the GL
version is at least 3.2 desktop.  Since compute_version() only enables
GL 3.2 functionality when GLSL 1.50 support is present, a sufficient
way for a back-end to advertise geometry shader support is to set
ctx->Const.GLSLVersion >= 150.

v2: Remove unnecessary ctx->Const.GeometryShaders150 constant.

Reviewed-by: Ian Romanick <[email protected]>
Reviewed-by: Kenneth Graunke <[email protected]>

1 files changed, 2 insertions, 3 deletions

diff --git a/src/mesa/main/shaderapi.c b/src/mesa/main/shaderapi.c
index c3011f58f0e..3f9402c598c 100644
--- a/src/mesa/main/shaderapi.c
+++ b/src/mesa/main/shaderapi.c
@@ -179,7 +179,7 @@ validate_shader_target(const struct gl_context *ctx, GLenum type)
    case GL_VERTEX_SHADER:
       return ctx->Extensions.ARB_vertex_shader;
    case GL_GEOMETRY_SHADER_ARB:
-      return _mesa_is_desktop_gl(ctx) && ctx->Extensions.ARB_geometry_shader4;
+      return _mesa_has_geometry_shaders(ctx);
    default:
       return false;
    }
@@ -478,8 +478,7 @@ get_programiv(struct gl_context *ctx, GLuint program, GLenum pname, GLint *param
 
    /* Are geometry shaders available in this context?
     */
-   const bool has_gs =
-      _mesa_is_desktop_gl(ctx) && ctx->Extensions.ARB_geometry_shader4;
+   const bool has_gs = _mesa_has_geometry_shaders(ctx);
 
    /* Are uniform buffer objects available in this context?
     */