3 files changed, 80 insertions, 1 deletions

diff --git a/src/mesa/main/api_validate.c b/src/mesa/main/api_validate.c
index 355a93c4c3d..16062820ef9 100644
--- a/src/mesa/main/api_validate.c
+++ b/src/mesa/main/api_validate.c
@@ -516,6 +516,8 @@ GLboolean
 _mesa_validate_DrawArrays(struct gl_context *ctx,
 			  GLenum mode, GLint start, GLsizei count)
 {
+   struct gl_transform_feedback_object *xfb_obj
+      = ctx->TransformFeedback.CurrentObject;
    ASSERT_OUTSIDE_BEGIN_END_WITH_RETVAL(ctx, GL_FALSE);
    FLUSH_CURRENT(ctx, 0);
 
@@ -537,6 +539,29 @@ _mesa_validate_DrawArrays(struct gl_context *ctx,
          return GL_FALSE;
    }
 
+   /* From the GLES3 specification, section 2.14.2 (Transform Feedback
+    * Primitive Capture):
+    *
+    *   The error INVALID_OPERATION is generated by DrawArrays and
+    *   DrawArraysInstanced if recording the vertices of a primitive to the
+    *   buffer objects being used for transform feedback purposes would result
+    *   in either exceeding the limits of any buffer object’s size, or in
+    *   exceeding the end position offset + size − 1, as set by
+    *   BindBufferRange.
+    *
+    * This is in contrast to the behaviour of desktop GL, where the extra
+    * primitives are silently dropped from the transform feedback buffer.
+    */
+   if (_mesa_is_gles3(ctx) && xfb_obj->Active && !xfb_obj->Paused) {
+      size_t prim_count = vbo_count_tessellated_primitives(mode, count, 1);
+      if (xfb_obj->GlesRemainingPrims < prim_count) {
+         _mesa_error(ctx, GL_INVALID_OPERATION,
+                     "glDrawArrays(exceeds transform feedback size)");
+         return GL_FALSE;
+      }
+      xfb_obj->GlesRemainingPrims -= prim_count;
+   }
+
    return GL_TRUE;
 }
 
@@ -545,6 +570,8 @@ GLboolean
 _mesa_validate_DrawArraysInstanced(struct gl_context *ctx, GLenum mode, GLint first,
                                    GLsizei count, GLsizei numInstances)
 {
+   struct gl_transform_feedback_object *xfb_obj
+      = ctx->TransformFeedback.CurrentObject;
    ASSERT_OUTSIDE_BEGIN_END_WITH_RETVAL(ctx, GL_FALSE);
    FLUSH_CURRENT(ctx, 0);
 
@@ -580,6 +607,30 @@ _mesa_validate_DrawArraysInstanced(struct gl_context *ctx, GLenum mode, GLint fi
          return GL_FALSE;
    }
 
+   /* From the GLES3 specification, section 2.14.2 (Transform Feedback
+    * Primitive Capture):
+    *
+    *   The error INVALID_OPERATION is generated by DrawArrays and
+    *   DrawArraysInstanced if recording the vertices of a primitive to the
+    *   buffer objects being used for transform feedback purposes would result
+    *   in either exceeding the limits of any buffer object’s size, or in
+    *   exceeding the end position offset + size − 1, as set by
+    *   BindBufferRange.
+    *
+    * This is in contrast to the behaviour of desktop GL, where the extra
+    * primitives are silently dropped from the transform feedback buffer.
+    */
+   if (_mesa_is_gles3(ctx) && xfb_obj->Active && !xfb_obj->Paused) {
+      size_t prim_count
+         = vbo_count_tessellated_primitives(mode, count, numInstances);
+      if (xfb_obj->GlesRemainingPrims < prim_count) {
+         _mesa_error(ctx, GL_INVALID_OPERATION,
+                     "glDrawArraysInstanced(exceeds transform feedback size)");
+         return GL_FALSE;
+      }
+      xfb_obj->GlesRemainingPrims -= prim_count;
+   }
+
    return GL_TRUE;
 }
 
diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index 67eaadd9f0d..0c201d08f46 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -1808,6 +1808,17 @@ struct gl_transform_feedback_object
    GLboolean EndedAnytime; /**< Has EndTransformFeedback been called
                                 at least once? */
 
+   /**
+    * GLES: if Active is true, remaining number of primitives which can be
+    * rendered without overflow.  This is necessary to track because GLES
+    * requires us to generate INVALID_OPERATION if a call to glDrawArrays or
+    * glDrawArraysInstanced would overflow transform feedback buffers.
+    * Undefined if Active is false.
+    *
+    * Not tracked for desktop GL since it's unnecessary.
+    */
+   unsigned GlesRemainingPrims;
+
    /** The feedback buffers */
    GLuint BufferNames[MAX_FEEDBACK_BUFFERS];
    struct gl_buffer_object *Buffers[MAX_FEEDBACK_BUFFERS];
diff --git a/src/mesa/main/transformfeedback.c b/src/mesa/main/transformfeedback.c
index d9c6e514e8f..b2818caa591 100644
--- a/src/mesa/main/transformfeedback.c
+++ b/src/mesa/main/transformfeedback.c
@@ -285,6 +285,7 @@ _mesa_BeginTransformFeedback(GLenum mode)
    struct gl_transform_feedback_object *obj;
    struct gl_transform_feedback_info *info;
    GLuint i;
+   unsigned vertices_per_prim;
    GET_CURRENT_CONTEXT(ctx);
 
    obj = ctx->TransformFeedback.CurrentObject;
@@ -305,9 +306,13 @@ _mesa_BeginTransformFeedback(GLenum mode)
 
    switch (mode) {
    case GL_POINTS:
+      vertices_per_prim = 1;
+      break;
    case GL_LINES:
+      vertices_per_prim = 2;
+      break;
    case GL_TRIANGLES:
-      /* legal */
+      vertices_per_prim = 3;
       break;
    default:
       _mesa_error(ctx, GL_INVALID_ENUM, "glBeginTransformFeedback(mode)");
@@ -333,6 +338,18 @@ _mesa_BeginTransformFeedback(GLenum mode)
    obj->Active = GL_TRUE;
    ctx->TransformFeedback.Mode = mode;
 
+   if (_mesa_is_gles3(ctx)) {
+      /* In GLES3, we are required to track the usage of the transform
+       * feedback buffer and report INVALID_OPERATION if a draw call tries to
+       * exceed it.  So compute the maximum number of vertices that we can
+       * write without overflowing any of the buffers currently being used for
+       * feedback.
+       */
+      unsigned max_vertices
+         = _mesa_compute_max_transform_feedback_vertices(obj, info);
+      obj->GlesRemainingPrims = max_vertices / vertices_per_prim;
+   }
+
    assert(ctx->Driver.BeginTransformFeedback);
    ctx->Driver.BeginTransformFeedback(ctx, mode, obj);
 }