mesa: implement DrawTransformFeedback from ARB_transform_feedback2

It's like DrawArrays, but the count is taken from a transform feedback
object.

This removes DrawTransformFeedback from dd_function_table and adds the same
function to GLvertexformat (with the function parameters matching GL).

The vbo_draw_func callback has a new parameter
"struct gl_transform_feedback_object *tfb_vertcount".

The rest of the code just validates states and forwards the transform
feedback object into vbo_draw_func.

1 files changed, 34 insertions, 0 deletions

diff --git a/src/mesa/main/api_validate.c b/src/mesa/main/api_validate.c
index efdecb212aa..945f12752d3 100644
--- a/src/mesa/main/api_validate.c
+++ b/src/mesa/main/api_validate.c
@@ -474,3 +474,37 @@ _mesa_validate_DrawElementsInstanced(struct gl_context *ctx,
 
    return GL_TRUE;
 }
+
+
+#if FEATURE_EXT_transform_feedback
+
+GLboolean
+_mesa_validate_DrawTransformFeedback(struct gl_context *ctx,
+                                     GLenum mode,
+                                     struct gl_transform_feedback_object *obj)
+{
+   ASSERT_OUTSIDE_BEGIN_END_WITH_RETVAL(ctx, GL_FALSE);
+
+   if (!_mesa_valid_prim_mode(ctx, mode)) {
+      _mesa_error(ctx, GL_INVALID_ENUM, "glDrawTransformFeedback(mode)");
+      return GL_FALSE;
+   }
+
+   if (!obj) {
+      _mesa_error(ctx, GL_INVALID_VALUE, "glDrawTransformFeedback(name)");
+      return GL_FALSE;
+   }
+
+   if (!obj->EndedAnytime) {
+      _mesa_error(ctx, GL_INVALID_OPERATION, "glDrawTransformFeedback");
+      return GL_FALSE;
+   }
+
+   if (!check_valid_to_render(ctx, "glDrawTransformFeedback")) {
+      return GL_FALSE;
+   }
+
+   return GL_TRUE;
+}
+
+#endif