[Mesa-dev] [PATCH 2/2] st/mesa: add support for gl_ClipDistance

[Bryan Cain]

---
 src/mesa/state_tracker/st_glsl_to_tgsi.cpp |   48 +++++++++++++++++++++++++---
 src/mesa/state_tracker/st_program.c        |   18 ++++++++++
 2 files changed, 61 insertions(+), 5 deletions(-)

diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index 1515fc1..bc3005e 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -304,6 +304,7 @@ public:
    int samplers_used;
    bool indirect_addr_temps;
    bool indirect_addr_consts;
+   int num_clip_distances;
    
    int glsl_version;
    bool native_integers;
@@ -4627,9 +4628,17 @@ st_translate_program(
       }
 
       for (i = 0; i < numOutputs; i++) {
-         t->outputs[i] = ureg_DECL_output(ureg,
-                                          outputSemanticName[i],
-                                          outputSemanticIndex[i]);
+         if (outputSemanticName[i] == TGSI_SEMANTIC_CLIPDIST) {
+            int mask = ((1 << (program->num_clip_distances - 4*outputSemanticIndex[i])) - 1) & TGSI_WRITEMASK_XYZW;
+            t->outputs[i] = ureg_DECL_output_masked(ureg,
+                                                    outputSemanticName[i],
+                                                    outputSemanticIndex[i],
+                                                    mask);
+         } else {
+            t->outputs[i] = ureg_DECL_output(ureg,
+                                             outputSemanticName[i],
+                                             outputSemanticIndex[i]);
+         }
          if ((outputSemanticName[i] == TGSI_SEMANTIC_PSIZE) && proginfo->Id) {
             /* Writing to the point size result register requires special
              * handling to implement clamping.
@@ -4806,7 +4815,8 @@ out:
 static struct gl_program *
 get_mesa_program(struct gl_context *ctx,
                  struct gl_shader_program *shader_program,
-        	 struct gl_shader *shader)
+                 struct gl_shader *shader,
+                 int num_clip_distances)
 {
    glsl_to_tgsi_visitor* v = new glsl_to_tgsi_visitor();
    struct gl_program *prog;
@@ -4851,6 +4861,7 @@ get_mesa_program(struct gl_context *ctx,
    v->options = options;
    v->glsl_version = ctx->Const.GLSLVersion;
    v->native_integers = ctx->Const.NativeIntegers;
+   v->num_clip_distances = num_clip_distances;
 
    _mesa_generate_parameters_list_for_uniforms(shader_program, shader,
 					       prog->Parameters);
@@ -4980,6 +4991,25 @@ get_mesa_program(struct gl_context *ctx,
    return prog;
 }
 
+/**
+ * Searches through the IR for a declaration of gl_ClipDistance and returns the
+ * declared size of the gl_ClipDistance array.  Returns 0 if gl_ClipDistance is
+ * not declared in the IR.
+ */
+int get_clip_distance_size(exec_list *ir)
+{
+   foreach_iter (exec_list_iterator, iter, *ir) {
+      ir_instruction *inst = (ir_instruction *)iter.get();
+      ir_variable *var = inst->as_variable();
+      if (var == NULL) continue;
+      if (!strcmp(var->name, "gl_ClipDistance")) {
+         return var->type->length;
+      }
+   }
+   
+   return 0;
+}
+
 extern "C" {
 
 struct gl_shader *
@@ -5018,6 +5048,7 @@ st_new_shader_program(struct gl_context *ctx, GLuint name)
 GLboolean
 st_link_shader(struct gl_context *ctx, struct gl_shader_program *prog)
 {
+   int num_clip_distances[MESA_SHADER_TYPES];
    assert(prog->LinkStatus);
 
    for (unsigned i = 0; i < MESA_SHADER_TYPES; i++) {
@@ -5029,6 +5060,11 @@ st_link_shader(struct gl_context *ctx, struct gl_shader_program *prog)
       const struct gl_shader_compiler_options *options =
             &ctx->ShaderCompilerOptions[_mesa_shader_type_to_index(prog->_LinkedShaders[i]->Type)];
 
+      /* We have to determine the length of the gl_ClipDistance array before
+       * the array is lowered to two vec4s by lower_clip_distance().
+       */
+      num_clip_distances[i] = get_clip_distance_size(ir);
+
       do {
          progress = false;
 
@@ -5045,6 +5081,7 @@ st_link_shader(struct gl_context *ctx, struct gl_shader_program *prog)
 	   || progress;
 
          progress = lower_quadop_vector(ir, false) || progress;
+         progress = lower_clip_distance(ir) || progress;
 
          if (options->MaxIfDepth == 0)
             progress = lower_discard(ir) || progress;
@@ -5079,7 +5116,8 @@ st_link_shader(struct gl_context *ctx, struct gl_shader_program *prog)
       if (prog->_LinkedShaders[i] == NULL)
          continue;
 
-      linked_prog = get_mesa_program(ctx, prog, prog->_LinkedShaders[i]);
+      linked_prog = get_mesa_program(ctx, prog, prog->_LinkedShaders[i],
+                                     num_clip_distances[i]);
 
       if (linked_prog) {
 	 static const GLenum targets[] = {
diff --git a/src/mesa/state_tracker/st_program.c b/src/mesa/state_tracker/st_program.c
index d62bfcd..aceaaf8 100644
--- a/src/mesa/state_tracker/st_program.c
+++ b/src/mesa/state_tracker/st_program.c
@@ -244,6 +244,14 @@ st_prepare_vertex_program(struct gl_context *ctx,
             stvp->output_semantic_name[slot] = TGSI_SEMANTIC_PSIZE;
             stvp->output_semantic_index[slot] = 0;
             break;
+         case VERT_RESULT_CLIP_DIST0:
+            stvp->output_semantic_name[slot] = TGSI_SEMANTIC_CLIPDIST;
+            stvp->output_semantic_index[slot] = 0;
+            break;
+         case VERT_RESULT_CLIP_DIST1:
+            stvp->output_semantic_name[slot] = TGSI_SEMANTIC_CLIPDIST;
+            stvp->output_semantic_index[slot] = 1;
+            break;
          case VERT_RESULT_EDGE:
             assert(0);
             break;
@@ -547,6 +555,16 @@ st_translate_fragment_program(struct st_context *st,
                input_semantic_index[slot] = 0;
                interpMode[slot] = TGSI_INTERPOLATE_CONSTANT;
                break;
+            case FRAG_ATTRIB_CLIP_DIST0:
+               input_semantic_name[slot] = TGSI_SEMANTIC_CLIPDIST;
+               input_semantic_index[slot] = 0;
+               interpMode[slot] = TGSI_INTERPOLATE_LINEAR;
+               break;
+            case FRAG_ATTRIB_CLIP_DIST1:
+               input_semantic_name[slot] = TGSI_SEMANTIC_CLIPDIST;
+               input_semantic_index[slot] = 1;
+               interpMode[slot] = TGSI_INTERPOLATE_LINEAR;
+               break;
                /* In most cases, there is nothing special about these
                 * inputs, so adopt a convention to use the generic
                 * semantic name and the mesa FRAG_ATTRIB_ number as the
-- 
1.7.1