i965: Move legacy clip plane handling to vec4_vs_visitor.

This is now only used for the vertex shader, so it makes sense to get it
out of any paths run by the geometry shader.

Instead of passing the gl_clip_plane array into the run() method (which
is shared among all subclasses), we add it as a vec4_vs_visitor
constructor parameter.  This eliminates the bogus NULL parameter in the
GS case.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>

1 files changed, 62 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_vec4_vs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_vs_visitor.cpp
index 620f652..f81ee4e 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_vs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_vs_visitor.cpp
@@ -202,8 +202,68 @@ vec4_vs_visitor::emit_urb_write_opcode(bool complete)
 
 
 void
+vec4_vs_visitor::emit_clip_distances(dst_reg reg, int offset)
+{
+   /* From the GLSL 1.30 spec, section 7.1 (Vertex Shader Special Variables):
+    *
+    *     "If a linked set of shaders forming the vertex stage contains no
+    *     static write to gl_ClipVertex or gl_ClipDistance, but the
+    *     application has requested clipping against user clip planes through
+    *     the API, then the coordinate written to gl_Position is used for
+    *     comparison against the user clip planes."
+    *
+    * This function is only called if the shader didn't write to
+    * gl_ClipDistance.  Accordingly, we use gl_ClipVertex to perform clipping
+    * if the user wrote to it; otherwise we use gl_Position.
+    */
+   gl_varying_slot clip_vertex = VARYING_SLOT_CLIP_VERTEX;
+   if (!(prog_data->vue_map.slots_valid & VARYING_BIT_CLIP_VERTEX)) {
+      clip_vertex = VARYING_SLOT_POS;
+   }
+
+   for (int i = 0; i + offset < key->base.nr_userclip_plane_consts && i < 4;
+        ++i) {
+      reg.writemask = 1 << i;
+      emit(DP4(reg,
+               src_reg(output_reg[clip_vertex]),
+               src_reg(this->userplane[i + offset])));
+   }
+}
+
+
+void
+vec4_vs_visitor::setup_uniform_clipplane_values()
+{
+   for (int i = 0; i < key->base.nr_userclip_plane_consts; ++i) {
+      assert(this->uniforms < uniform_array_size);
+      this->uniform_vector_size[this->uniforms] = 4;
+      this->userplane[i] = dst_reg(UNIFORM, this->uniforms);
+      this->userplane[i].type = BRW_REGISTER_TYPE_F;
+      for (int j = 0; j < 4; ++j) {
+         stage_prog_data->param[this->uniforms * 4 + j] =
+            (gl_constant_value *) &clip_planes[i][j];
+      }
+      ++this->uniforms;
+   }
+}
+
+
+void
 vec4_vs_visitor::emit_thread_end()
 {
+   setup_uniform_clipplane_values();
+
+   /* Lower legacy ff and ClipVertex clipping to clip distances */
+   if (key->base.nr_userclip_plane_consts > 0) {
+      current_annotation = "user clip distances";
+
+      output_reg[VARYING_SLOT_CLIP_DIST0] = dst_reg(this, glsl_type::vec4_type);
+      output_reg[VARYING_SLOT_CLIP_DIST1] = dst_reg(this, glsl_type::vec4_type);
+
+      emit_clip_distances(output_reg[VARYING_SLOT_CLIP_DIST0], 0);
+      emit_clip_distances(output_reg[VARYING_SLOT_CLIP_DIST1], 4);
+   }
+
    /* For VS, we always end the thread by emitting a single vertex.
     * emit_urb_write_opcode() will take care of setting the eot flag on the
     * SEND instruction.
@@ -218,6 +278,7 @@ vec4_vs_visitor::vec4_vs_visitor(const struct brw_compiler *compiler,
                                  struct brw_vs_prog_data *vs_prog_data,
                                  struct gl_vertex_program *vp,
                                  struct gl_shader_program *prog,
+                                 gl_clip_plane *clip_planes,
                                  void *mem_ctx,
                                  int shader_time_index,
                                  bool use_legacy_snorm_formula)
@@ -229,6 +290,7 @@ vec4_vs_visitor::vec4_vs_visitor(const struct brw_compiler *compiler,
      key(key),
      vs_prog_data(vs_prog_data),
      vp(vp),
+     clip_planes(clip_planes),
      use_legacy_snorm_formula(use_legacy_snorm_formula)
 {
 }