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, 11 insertions, 0 deletions

diff --git a/src/mesa/main/context.h b/src/mesa/main/context.h
index 8872be1f4f5..792ab4cd55e 100644
--- a/src/mesa/main/context.h
+++ b/src/mesa/main/context.h
@@ -312,6 +312,17 @@ _mesa_is_gles3(const struct gl_context *ctx)
 }
 
 
+/**
+ * Checks if the context supports geometry shaders.
+ */
+static inline GLboolean
+_mesa_has_geometry_shaders(const struct gl_context *ctx)
+{
+   return _mesa_is_desktop_gl(ctx) &&
+      (ctx->Version >= 32 || ctx->Extensions.ARB_geometry_shader4);
+}
+
+
 #ifdef __cplusplus
 }
 #endif