From c664f0c5155da800c34de1783754313e86654eda Mon Sep 17 00:00:00 2001
From: Keith Whitwell <keith@tungstengraphics.com>
Date: Thu, 30 Dec 2004 16:30:26 +0000
Subject: Calculate DEPTH_SCALE correctly for polygon offset.

---
 src/mesa/drivers/dri/unichrome/via_context.c | 3 +++
 src/mesa/drivers/dri/unichrome/via_context.h | 1 +
 src/mesa/drivers/dri/unichrome/via_tris.c    | 2 +-
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/mesa/drivers/dri/unichrome/via_context.c b/src/mesa/drivers/dri/unichrome/via_context.c
index b3cc66f087..4c70af60c8 100644
--- a/src/mesa/drivers/dri/unichrome/via_context.c
+++ b/src/mesa/drivers/dri/unichrome/via_context.c
@@ -356,6 +356,7 @@ viaCreateContext(const __GLcontextModes *mesaVis,
        vmesa->depth_max = (GLfloat)0xffff;
        vmesa->depth_clear_mask = 0xf << 28;
        vmesa->ClearDepth = 0xffff;
+       vmesa->polygon_offset_scale = 1.0 / vmesa->depth_max;
        break;
     case 24:
        vmesa->hasDepth = GL_TRUE;
@@ -370,6 +371,7 @@ viaCreateContext(const __GLcontextModes *mesaVis,
        vmesa->have_hw_stencil = GL_TRUE;
        vmesa->stencilBits = mesaVis->stencilBits;
        vmesa->stencil_clear_mask = 0x1 << 28;
+       vmesa->polygon_offset_scale = 2.0 / vmesa->depth_max;
        break;
     case 32:
        vmesa->hasDepth = GL_TRUE;
@@ -380,6 +382,7 @@ viaCreateContext(const __GLcontextModes *mesaVis,
        vmesa->depth_clear_mask = 0;
        vmesa->ClearDepth = 0xffffffff;
        vmesa->depth_clear_mask = 0xf << 28;
+       vmesa->polygon_offset_scale = 2.0 / vmesa->depth_max;
        break;
     default:
        assert(0); 
diff --git a/src/mesa/drivers/dri/unichrome/via_context.h b/src/mesa/drivers/dri/unichrome/via_context.h
index 25def2e075..a409b8c6b7 100644
--- a/src/mesa/drivers/dri/unichrome/via_context.h
+++ b/src/mesa/drivers/dri/unichrome/via_context.h
@@ -103,6 +103,7 @@ struct via_context_t {
    GLuint depth_clear_mask;
    GLuint stencil_clear_mask;
    GLfloat depth_max;
+   GLfloat polygon_offset_scale;
 
     GLubyte    *dma;
     viaRegion tex;
diff --git a/src/mesa/drivers/dri/unichrome/via_tris.c b/src/mesa/drivers/dri/unichrome/via_tris.c
index 6dbbfe0343..8c16d01000 100644
--- a/src/mesa/drivers/dri/unichrome/via_tris.c
+++ b/src/mesa/drivers/dri/unichrome/via_tris.c
@@ -222,7 +222,7 @@ static struct {
     } while (0)
 
 
-#define DEPTH_SCALE (1.0 / 0xffff)
+#define DEPTH_SCALE vmesa->polygon_offset_scale
 #define UNFILLED_TRI unfilled_tri
 #define UNFILLED_QUAD unfilled_quad
 #define VERT_X(_v) _v->v.x
-- 
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