[Mesa-dev] [RFC PATCH 07/56] mesa: Allow drawing of patch primitives

[Chris Forbes]

Signed-off-by: Chris Forbes <chrisf at ijw.co.nz>
---
 src/mesa/main/api_validate.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/src/mesa/main/api_validate.c b/src/mesa/main/api_validate.c
index 51a3d1f..64ed465 100644
--- a/src/mesa/main/api_validate.c
+++ b/src/mesa/main/api_validate.c
@@ -186,6 +186,8 @@ _mesa_is_valid_prim_mode(struct gl_context *ctx, GLenum mode)
    case GL_TRIANGLES_ADJACENCY:
    case GL_TRIANGLE_STRIP_ADJACENCY:
       return _mesa_has_geometry_shaders(ctx);
+   case GL_PATCHES:
+      return ctx->Extensions.ARB_tessellation_shader;
    default:
       return false;
    }
@@ -197,6 +199,7 @@ _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)
@@ -232,7 +235,8 @@ _mesa_valid_prim_mode(struct gl_context *ctx, GLenum mode, const char *name)
     *   TRIANGLES_ADJACENCY_ARB or TRIANGLE_STRIP_ADJACENCY_ARB.
     *
    */
-   if (ctx->_Shader->CurrentProgram[MESA_SHADER_GEOMETRY]) {
+   if (ctx->_Shader->CurrentProgram[MESA_SHADER_GEOMETRY] &&
+       !ctx->_Shader->CurrentProgram[MESA_SHADER_TESS_EVAL]) {
       const GLenum geom_mode =
          ctx->_Shader->CurrentProgram[MESA_SHADER_GEOMETRY]->Geom.InputType;
       switch (mode) {
@@ -276,6 +280,35 @@ _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
@@ -308,6 +341,14 @@ _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]) {
+         if (ctx->Shader.CurrentProgram[MESA_SHADER_TESS_EVAL]->TessEval.PointMode)
+            pass = ctx->TransformFeedback.Mode == GL_POINTS;
+         else if (ctx->Shader.CurrentProgram[MESA_SHADER_TESS_EVAL]->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