From c77b257094b15e7c53b62cb50bfbcd7c5003f2a8 Mon Sep 17 00:00:00 2001
From: Ian Romanick <ian.d.romanick@intel.com>
Date: Wed, 7 Apr 2010 16:59:46 -0700
Subject: [PATCH] Add support for GL_ARB_draw_buffers extension

---
 glsl_parser_extras.cpp |  9 +++++++++
 glsl_parser_extras.h   |  8 ++++++++
 ir_variable.cpp        | 43 ++++++++++++++++++++++++++++++++++++------
 3 files changed, 54 insertions(+), 6 deletions(-)

diff --git a/glsl_parser_extras.cpp b/glsl_parser_extras.cpp
index 6cd69c8b882..553cd675a7a 100644
--- a/glsl_parser_extras.cpp
+++ b/glsl_parser_extras.cpp
@@ -126,6 +126,15 @@ _mesa_glsl_process_extension(const char *name, YYLTYPE *name_locp,
 			  ? "enable" : "require");
 	 return false;
       }
+   } if (strcmp(name, "GL_ARB_draw_buffers") == 0) {
+      /* This extension is only supported in fragment shaders.
+       */
+      if (state->target != fragment_shader) {
+	 unsupported = true;
+      } else {
+	 state->ARB_draw_buffers_enable = (ext_mode != extension_disable);
+	 state->ARB_draw_buffers_warn = (ext_mode == extension_warn);
+      }
    } else {
       unsupported = true;
    }
diff --git a/glsl_parser_extras.h b/glsl_parser_extras.h
index 7759eda535f..51e4eb89ccf 100644
--- a/glsl_parser_extras.h
+++ b/glsl_parser_extras.h
@@ -59,6 +59,14 @@ struct _mesa_glsl_parse_state {
 
    /** Loop or switch statement containing the current instructions. */
    class ir_instruction *loop_or_switch_nesting;
+
+   /**
+    * \name Enable bits for GLSL extensions
+    */
+   /*@{*/
+   unsigned ARB_draw_buffers_enable:1;
+   unsigned ARB_draw_buffers_warn:1;
+   /*@}*/
 };
 
 typedef struct YYLTYPE {
diff --git a/ir_variable.cpp b/ir_variable.cpp
index 41359b56162..76a528ca2be 100644
--- a/ir_variable.cpp
+++ b/ir_variable.cpp
@@ -30,7 +30,7 @@
 #define Elements(x) (sizeof(x)/sizeof(*(x)))
 #endif
 
-static void
+static ir_variable *
 add_variable(const char *name, enum ir_variable_mode mode,
 	     const glsl_type *type, exec_list *instructions,
 		     glsl_symbol_table *symtab)
@@ -48,6 +48,7 @@ add_variable(const char *name, enum ir_variable_mode mode,
    instructions->push_tail(var);
 
    symtab->add_variable(var->name, var);
+   return var;
 }
 
 
@@ -197,8 +198,6 @@ generate_110_fs_variables(exec_list *instructions,
    }
    generate_110_uniforms(instructions, symtab);
 
-   /* FINISHME: Add support for gl_FragData[GL_MAX_DRAW_BUFFERS]. */
-
    /* FINISHME: The size of this array is implementation dependent based on the
     * FINISHME: value of GL_MAX_TEXTURE_COORDS.  GL_MAX_TEXTURE_COORDS must be
     * FINISHME: at least 2, so hard-code 2 for now.
@@ -212,14 +211,35 @@ generate_110_fs_variables(exec_list *instructions,
 		symtab);
 }
 
+
+static void
+generate_ARB_draw_buffers_fs_variables(exec_list *instructions,
+				       glsl_symbol_table *symtab, bool warn)
+{
+   /* FINISHME: The size of this array is implementation dependent based on the
+    * FINISHME: value of GL_MAX_DRAW_BUFFERS.  GL_MAX_DRAW_BUFFERS must be
+    * FINISHME: at least 1, so hard-code 1 for now.
+    */
+   const glsl_type *const vec4_type =
+      glsl_type::get_instance(GLSL_TYPE_FLOAT, 4, 1);
+   const glsl_type *const vec4_array_type =
+      glsl_type::get_array_instance(vec4_type, 1);
+
+   ir_variable *const fd =
+      add_variable("gl_FragData", ir_var_out, vec4_array_type, instructions,
+		   symtab);
+
+   if (warn)
+      fd->warn_extension = "GL_ARB_draw_buffers";
+}
+
+
 static void
 generate_120_fs_variables(exec_list *instructions,
 			  glsl_symbol_table *symtab)
 {
-   /* GLSL version 1.20 did not add any built-in variables in the fragment
-    * shader.
-    */
    generate_110_fs_variables(instructions, symtab);
+   generate_ARB_draw_buffers_fs_variables(instructions, symtab, false);
 }
 
 static void
@@ -253,6 +273,17 @@ initialize_fs_variables(exec_list *instructions,
       generate_130_fs_variables(instructions, state->symbols);
       break;
    }
+
+
+   /* Since GL_ARB_draw_buffers is included in GLSL 1.20 and later, we
+    * can basically ignore any extension settings for it.
+    */
+   if (state->language_version < 120) {
+      if (state->ARB_draw_buffers_enable) {
+	 generate_ARB_draw_buffers_fs_variables(instructions, state->symbols,
+						state->ARB_draw_buffers_warn);
+      }
+   }
 }
 
 void
-- 
2.30.2