From e415dced44bd716185e63df0c8c17f57de2b29e2 Mon Sep 17 00:00:00 2001
From: Brian <brian@i915.localnet.net>
Date: Thu, 2 Aug 2007 10:29:42 -0600
Subject: [PATCH] sketch out clearing with quads

---
 src/mesa/state_tracker/st_cb_clear.c | 84 ++++++++++++++++++++++++++--
 1 file changed, 79 insertions(+), 5 deletions(-)

diff --git a/src/mesa/state_tracker/st_cb_clear.c b/src/mesa/state_tracker/st_cb_clear.c
index d9cb83b8ad2..523a9b682cf 100644
--- a/src/mesa/state_tracker/st_cb_clear.c
+++ b/src/mesa/state_tracker/st_cb_clear.c
@@ -1,6 +1,6 @@
 /**************************************************************************
  * 
- * Copyright 2003 Tungsten Graphics, Inc., Cedar Park, Texas.
+ * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
  * All Rights Reserved.
  * 
  * Permission is hereby granted, free of charge, to any person obtaining a
@@ -31,17 +31,85 @@
   *   Brian Paul
   */
 
-#include "st_context.h"
 #include "glheader.h"
 #include "macros.h"
 #include "enums.h"
-#include "st_context.h"
 #include "st_atom.h"
+#include "st_context.h"
+#include "st_cb_clear.h"
+#include "st_public.h"
 #include "pipe/p_context.h"
+#include "pipe/p_defines.h"
+
+
+
+/**
+ * Do glClear by drawing a quadrilateral.
+ */
+static void
+clear_with_quad(GLcontext *ctx,
+                GLboolean color, GLboolean depth,
+                GLboolean stencil, GLboolean accum)
+{
+   struct st_context *st = ctx->st;
+   struct pipe_blend_state blend;
+   struct pipe_depth_state depth_test;
+   struct pipe_stencil_state stencil_test;
+   GLfloat z = ctx->Depth.Clear;
+
+   /* depth state: always pass */
+   memset(&depth_test, 0, sizeof(depth));
+   if (depth) {
+      depth_test.enabled = 1;
+      depth_test.writemask = 1;
+      depth_test.func = PIPE_FUNC_ALWAYS;
+   }
+   st->pipe->set_depth_state(st->pipe, &depth_test);
+
+   /* stencil state: always set to ref value */
+   memset(&stencil_test, 0, sizeof(stencil));
+   if (stencil) {
+      stencil_test.front_enabled = 1;
+      stencil_test.front_func = PIPE_FUNC_ALWAYS;
+      stencil_test.front_fail_op = PIPE_STENCIL_OP_REPLACE;
+      stencil_test.front_zpass_op = PIPE_STENCIL_OP_REPLACE;
+      stencil_test.front_zfail_op = PIPE_STENCIL_OP_REPLACE;
+      stencil_test.ref_value[0] = ctx->Stencil.Clear;
+      stencil_test.value_mask[0] = 0xff;
+      stencil_test.write_mask[0] = ctx->Stencil.WriteMask[0];
+   }
+   st->pipe->set_stencil_state(st->pipe, &stencil_test);
+
+   /* blend state: RGBA masking */
+   memset(&blend, 0, sizeof(blend));
+   if (color) {
+      if (ctx->Color.ColorMask[0])
+         blend.colormask |= PIPE_MASK_R;
+      if (ctx->Color.ColorMask[1])
+         blend.colormask |= PIPE_MASK_G;
+      if (ctx->Color.ColorMask[2])
+         blend.colormask |= PIPE_MASK_B;
+      if (ctx->Color.ColorMask[3])
+         blend.colormask |= PIPE_MASK_A;
+      if (st->ctx->Color.DitherFlag)
+         blend.dither = 1;
+   }
+   st->pipe->set_blend_state(st->pipe, &blend);
 
 
+   /*
+    * XXX Render quad here
+    */
 
-/* XXX: doesn't pick up the differences between front/back/left/right
+   /* Restore GL state */
+   st_invalidate_state(ctx, _NEW_COLOR | _NEW_DEPTH | _NEW_STENCIL);
+}
+
+
+
+/**
+ * Called via ctx->Driver.Clear()
+ * XXX: doesn't pick up the differences between front/back/left/right
  * clears.  Need to sort that out...
  */
 static void st_clear(GLcontext *ctx, GLbitfield mask)
@@ -51,12 +119,17 @@ static void st_clear(GLcontext *ctx, GLbitfield mask)
    GLboolean depth = (mask & BUFFER_BIT_DEPTH) ? GL_TRUE : GL_FALSE;
    GLboolean stencil = (mask & BUFFER_BIT_STENCIL) ? GL_TRUE : GL_FALSE;
    GLboolean accum = (mask & BUFFER_BIT_ACCUM) ? GL_TRUE : GL_FALSE;
+   GLboolean maskColor, maskStencil;
    GLboolean fullscreen = 1;	/* :-) */
+   GLuint stencilMax = 1 << ctx->DrawBuffer->_StencilBuffer->StencilBits;
 
    /* This makes sure the softpipe has the latest scissor, etc values */
    st_validate_state( st );
 
-   if (fullscreen) {
+   maskColor = st->state.blend.colormask != PIPE_MASK_RGBA;
+   maskStencil = ctx->Stencil.WriteMask[0] != stencilMax;
+
+   if (fullscreen && !maskColor) {
       /* pipe->clear() should clear a particular surface, so that we
        * can iterate over render buffers at this level and clear the
        * ones GL is asking for.  
@@ -71,6 +144,7 @@ static void st_clear(GLcontext *ctx, GLbitfield mask)
    else {
       /* Convert to geometry, etc:
        */
+      clear_with_quad(ctx, color, depth, stencil, accum);
    }
 }
 
-- 
2.30.2