[Mesa-dev] [PATCH 09/46] mesa: allow drawing of patch primitives

[Marek Olšák]

From: Chris Forbes <chrisf at ijw.co.nz>

Cosmetic changes and fixes by Marek.
---
 src/mesa/main/api_validate.c | 45 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/src/mesa/main/api_validate.c b/src/mesa/main/api_validate.c
index 9c2e29e..3871765 100644
--- a/src/mesa/main/api_validate.c
+++ b/src/mesa/main/api_validate.c
@@ -127,6 +127,9 @@ _mesa_is_valid_prim_mode(struct gl_context *ctx, GLenum mode)
    if (mode <= GL_TRIANGLE_STRIP_ADJACENCY)
       return _mesa_has_geometry_shaders(ctx);
 
+   if (mode == GL_PATCHES)
+      return _mesa_has_tessellation(ctx);
+
    return false;
 }
 
@@ -136,6 +139,7 @@ _mesa_is_valid_prim_mode(struct gl_context *ctx, GLenum mode)
  * etc?  Also, do additional checking related to transformation feedback.
  * Note: this function cannot be called during glNewList(GL_COMPILE) because
  * this code depends on current transform feedback state.
+ * Also, do additional checking related to tessellation shaders.
  */
 GLboolean
 _mesa_valid_prim_mode(struct gl_context *ctx, GLenum mode, const char *name)
@@ -215,6 +219,36 @@ _mesa_valid_prim_mode(struct gl_context *ctx, GLenum mode, const char *name)
       }
    }
 
+   /* From the OpenGL 4.0 (Core Profile) spec (section 2.12):
+    *
+    *     "Tessellation operates only on patch primitives. If tessellation is
+    *      active, any command that transfers vertices to the GL will
+    *      generate an INVALID_OPERATION error if the primitive mode is not
+    *      PATCHES.
+    *      Patch primitives are not supported by pipeline stages below the
+    *      tessellation evaluation shader. If there is no active program
+    *      object or the active program object does not contain a tessellation
+    *      evaluation shader, the error INVALID_OPERATION is generated by any
+    *      command that transfers vertices to the GL if the primitive mode is
+    *      PATCHES."
+    *
+    */
+   if (ctx->_Shader->CurrentProgram[MESA_SHADER_TESS_EVAL] ||
+       ctx->_Shader->CurrentProgram[MESA_SHADER_TESS_CTRL]) {
+      if (mode != GL_PATCHES) {
+         _mesa_error(ctx, GL_INVALID_OPERATION,
+                     "only GL_PATCHES valid with tessellation");
+         return GL_FALSE;
+      }
+   }
+   else {
+      if (mode == GL_PATCHES) {
+         _mesa_error(ctx, GL_INVALID_OPERATION,
+                     "GL_PATCHES only valid with tessellation");
+         return GL_FALSE;
+      }
+   }
+
    /* From the GL_EXT_transform_feedback spec:
     *
     *     "The error INVALID_OPERATION is generated if Begin, or any command
@@ -247,6 +281,17 @@ _mesa_valid_prim_mode(struct gl_context *ctx, GLenum mode, const char *name)
             pass = GL_FALSE;
          }
       }
+      else if (ctx->_Shader->CurrentProgram[MESA_SHADER_TESS_EVAL]) {
+         struct gl_shader_program *tes =
+            ctx->_Shader->CurrentProgram[MESA_SHADER_TESS_EVAL];
+
+         if (tes->TessEval.PointMode)
+            pass = ctx->TransformFeedback.Mode == GL_POINTS;
+         else if (tes->TessEval.PrimitiveMode == GL_ISOLINES)
+            pass = ctx->TransformFeedback.Mode == GL_LINES;
+         else
+            pass = ctx->TransformFeedback.Mode == GL_TRIANGLES;
+      }
       else {
          switch (mode) {
          case GL_POINTS:
-- 
2.1.0