From d0130a989a3b331eb8114f1ee4addb95ce31e0e2 Mon Sep 17 00:00:00 2001
From: Brian Paul <brian.paul@tungstengraphics.com>
Date: Tue, 11 Apr 2000 20:42:22 +0000
Subject: [PATCH] clip depth/stencil spans to window bounds

---
 src/mesa/main/depth.c   | 102 +++++++++++++++++++++++++++++++++++++++++++--
 src/mesa/main/depth.h   |   9 +++-
 src/mesa/main/drawpix.c |   4 +-
 src/mesa/main/stencil.c | 107 +++++++++++++++++++++++++++++-------------------
 src/mesa/main/stencil.h |  12 +++---
 5 files changed, 178 insertions(+), 56 deletions(-)

diff --git a/src/mesa/main/depth.c b/src/mesa/main/depth.c
index 88a0a1a..8a09206 100644
--- a/src/mesa/main/depth.c
+++ b/src/mesa/main/depth.c
@@ -1,4 +1,4 @@
-/* $Id: depth.c,v 1.16 2000/04/04 00:54:23 brianp Exp $ */
+/* $Id: depth.c,v 1.17 2000/04/11 20:42:22 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -1418,6 +1418,74 @@ _mesa_depth_test_pixels( GLcontext *ctx,
 
 
 /*
+ * Read a span of depth values from the depth buffer.
+ * This function does clipping before calling the device driver function.
+ */
+void
+_mesa_read_depth_span( GLcontext *ctx,
+                       GLint n, GLint x, GLint y, GLdepth depth[] )
+{
+   if (y < 0 || y >= ctx->DrawBuffer->Height ||
+       x + (GLint) n <= 0 || x >= ctx->DrawBuffer->Width) {
+      /* span is completely outside framebuffer */
+      GLint i;
+      for (i = 0; i < n; i++)
+         depth[i] = 0;
+      return;
+   }
+
+   if (x < 0) {
+      GLint dx = -x;
+      GLint i;
+      for (i = 0; i < dx; i++)
+         depth[i] = 0;
+      x = 0;
+      n -= dx;
+      depth += dx;
+   }
+   if (x + n > ctx->DrawBuffer->Width) {
+      GLint dx = x + n - ctx->DrawBuffer->Width;
+      GLint i;
+      for (i = 0; i < dx; i++)
+         depth[n - i - 1] = 0;
+      n -= dx;
+   }
+   if (n <= 0) {
+      return;
+   }
+
+   if (ctx->DrawBuffer->DepthBuffer) {
+      /* read from software depth buffer */
+      if (ctx->Visual->DepthBits <= 16) {
+         const GLushort *zptr = Z_ADDRESS16( ctx, x, y );
+         GLuint i;
+         for (i = 0; i < n; i++) {
+            depth[i] = zptr[i];
+         }
+      }
+      else {
+         const GLuint *zptr = Z_ADDRESS32( ctx, x, y );
+         GLuint i;
+         for (i = 0; i < n; i++) {
+            depth[i] = zptr[i];
+         }
+      }
+   }
+   else if (ctx->Driver.ReadDepthSpan) {
+      /* read from hardware depth buffer */
+      (*ctx->Driver.ReadDepthSpan)( ctx, n, x, y, depth );
+   }
+   else {
+      /* no depth buffer */
+      BZERO(depth, n * sizeof(GLfloat));
+   }
+
+}
+
+
+
+
+/*
  * Return a span of depth values from the depth buffer as floats in [0,1].
  * This is used for both hardware and software depth buffers.
  * Input:  n - how many pixels
@@ -1425,11 +1493,39 @@ _mesa_depth_test_pixels( GLcontext *ctx,
  * Output:  depth - the array of depth values
  */
 void
-_mesa_read_depth_span_float( GLcontext* ctx,
-                             GLuint n, GLint x, GLint y, GLfloat depth[] )
+_mesa_read_depth_span_float( GLcontext *ctx,
+                             GLint n, GLint x, GLint y, GLfloat depth[] )
 {
    const GLfloat scale = 1.0F / ctx->Visual->DepthMaxF;
 
+   if (y < 0 || y >= ctx->DrawBuffer->Height ||
+       x + (GLint) n <= 0 || x >= ctx->DrawBuffer->Width) {
+      /* span is completely outside framebuffer */
+      GLint i;
+      for (i = 0; i < n; i++)
+         depth[i] = 0.0F;
+      return;
+   }
+
+   if (x < 0) {
+      GLint dx = -x;
+      GLint i;
+      for (i = 0; i < dx; i++)
+         depth[i] = 0.0F;
+      n -= dx;
+      x = 0;
+   }
+   if (x + n > ctx->DrawBuffer->Width) {
+      GLint dx = x + n - ctx->DrawBuffer->Width;
+      GLint i;
+      for (i = 0; i < dx; i++)
+         depth[n - i - 1] = 0.0F;
+      n -= dx;
+   }
+   if (n <= 0) {
+      return;
+   }
+
    if (ctx->DrawBuffer->DepthBuffer) {
       /* read from software depth buffer */
       if (ctx->Visual->DepthBits <= 16) {
diff --git a/src/mesa/main/depth.h b/src/mesa/main/depth.h
index ec16ecf..ef17600 100644
--- a/src/mesa/main/depth.h
+++ b/src/mesa/main/depth.h
@@ -1,4 +1,4 @@
-/* $Id: depth.h,v 1.7 2000/03/03 17:47:39 brianp Exp $ */
+/* $Id: depth.h,v 1.8 2000/04/11 20:42:22 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -68,7 +68,12 @@ _mesa_depth_test_pixels( GLcontext *ctx,
 
 
 extern void
-_mesa_read_depth_span_float( GLcontext *ctx, GLuint n, GLint x, GLint y,
+_mesa_read_depth_span( GLcontext *ctx,
+                       GLint n, GLint x, GLint y, GLdepth depth[] );
+
+
+extern void
+_mesa_read_depth_span_float( GLcontext *ctx, GLint n, GLint x, GLint y,
                              GLfloat depth[] );
 
 
diff --git a/src/mesa/main/drawpix.c b/src/mesa/main/drawpix.c
index ad9ce92..184248c 100644
--- a/src/mesa/main/drawpix.c
+++ b/src/mesa/main/drawpix.c
@@ -1,4 +1,4 @@
-/* $Id: drawpix.c,v 1.18 2000/04/08 18:57:45 brianp Exp $ */
+/* $Id: drawpix.c,v 1.19 2000/04/11 20:42:22 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -479,7 +479,7 @@ draw_stencil_pixels( GLcontext *ctx, GLint x, GLint y,
                                        values, desty );
       }
       else {
-         gl_write_stencil_span( ctx, (GLuint) drawWidth, x, y, values );
+         _mesa_write_stencil_span( ctx, (GLuint) drawWidth, x, y, values );
       }
    }
 }
diff --git a/src/mesa/main/stencil.c b/src/mesa/main/stencil.c
index 79c66d3..ecd610d 100644
--- a/src/mesa/main/stencil.c
+++ b/src/mesa/main/stencil.c
@@ -1,4 +1,4 @@
-/* $Id: stencil.c,v 1.14 2000/02/02 22:16:04 brianp Exp $ */
+/* $Id: stencil.c,v 1.15 2000/04/11 20:42:22 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -1130,24 +1130,44 @@ gl_stencil_and_depth_test_pixels( GLcontext *ctx,
  *         x,y - location of first pixel
  * Output:  stencil - the array of stencil values
  */
-void gl_read_stencil_span( GLcontext *ctx,
-                           GLint n, GLint x, GLint y, GLstencil stencil[] )
+void
+_mesa_read_stencil_span( GLcontext *ctx,
+                         GLint n, GLint x, GLint y, GLstencil stencil[] )
 {
+   if (y < 0 || y >= ctx->DrawBuffer->Height ||
+       x + n <= 0 || x >= ctx->DrawBuffer->Width) {
+      /* span is completely outside framebuffer */
+      return; /* undefined values OK */
+   }
+
+   if (x < 0) {
+      GLint dx = -x;
+      x = 0;
+      n -= dx;
+      stencil += dx;
+   }
+   if (x + n > ctx->DrawBuffer->Width) {
+      GLint dx = x + n - ctx->DrawBuffer->Width;
+      n -= dx;
+   }
+   if (n <= 0) {
+      return;
+   }
+
+
    ASSERT(n >= 0);
-   if (ctx->DrawBuffer->Stencil) {
-      if (ctx->Driver.ReadStencilSpan) {
-         (*ctx->Driver.ReadStencilSpan)( ctx, (GLuint) n, x, y, stencil );
-      }
-      else {
-         const GLstencil *s = STENCIL_ADDRESS( x, y );
+   if (ctx->Driver.ReadStencilSpan) {
+      (*ctx->Driver.ReadStencilSpan)( ctx, (GLuint) n, x, y, stencil );
+   }
+   else if (ctx->DrawBuffer->Stencil) {
+      const GLstencil *s = STENCIL_ADDRESS( x, y );
 #if STENCIL_BITS == 8
-         MEMCPY( stencil, s, n * sizeof(GLstencil) );
+      MEMCPY( stencil, s, n * sizeof(GLstencil) );
 #else
-         GLuint i;
-         for (i=0;i<n;i++)
-            stencil[i] = s[i];
+      GLuint i;
+      for (i=0;i<n;i++)
+         stencil[i] = s[i];
 #endif
-      }
    }
 }
 
@@ -1160,41 +1180,42 @@ void gl_read_stencil_span( GLcontext *ctx,
  *         x, y - location of first pixel
  *         stencil - the array of stencil values
  */
-void gl_write_stencil_span( GLcontext *ctx,
-                            GLint n, GLint x, GLint y,
-			    const GLstencil stencil[] )
+void
+_mesa_write_stencil_span( GLcontext *ctx, GLint n, GLint x, GLint y,
+                          const GLstencil stencil[] )
 {
-   ASSERT(n >= 0);
-   if (ctx->DrawBuffer->Stencil) {
-      /* do clipping */
-      if (y < ctx->DrawBuffer->Ymin || y > ctx->DrawBuffer->Ymax)
-         return;
-      if (x < ctx->DrawBuffer->Xmin) {
-         GLint diff = ctx->DrawBuffer->Xmin - x;
-         n -= diff;
-         stencil += diff;
-         x = ctx->DrawBuffer->Xmin;
-      }
-      if (x + n > ctx->DrawBuffer->Xmax) {
-         GLint diff = x + n - ctx->DrawBuffer->Xmax;
-         n -= diff;
-      }
+   if (y < 0 || y >= ctx->DrawBuffer->Height ||
+       x + n <= 0 || x >= ctx->DrawBuffer->Width) {
+      /* span is completely outside framebuffer */
+      return; /* undefined values OK */
+   }
 
-      ASSERT( n >= 0);
+   if (x < 0) {
+      GLint dx = -x;
+      x = 0;
+      n -= dx;
+      stencil += dx;
+   }
+   if (x + n > ctx->DrawBuffer->Width) {
+      GLint dx = x + n - ctx->DrawBuffer->Width;
+      n -= dx;
+   }
+   if (n <= 0) {
+      return;
+   }
 
-      if (ctx->Driver.WriteStencilSpan) {
-         (*ctx->Driver.WriteStencilSpan)( ctx, n, x, y, stencil, NULL );
-      }
-      else {
-         GLstencil *s = STENCIL_ADDRESS( x, y );
+   if (ctx->Driver.WriteStencilSpan) {
+      (*ctx->Driver.WriteStencilSpan)( ctx, n, x, y, stencil, NULL );
+   }
+   else if (ctx->DrawBuffer->Stencil) {
+      GLstencil *s = STENCIL_ADDRESS( x, y );
 #if STENCIL_BITS == 8
-         MEMCPY( s, stencil, n * sizeof(GLstencil) );
+      MEMCPY( s, stencil, n * sizeof(GLstencil) );
 #else
-         GLuint i;
-         for (i=0;i<n;i++)
-            s[i] = stencil[i];
+      GLuint i;
+      for (i=0;i<n;i++)
+         s[i] = stencil[i];
 #endif
-      }
    }
 }
 
diff --git a/src/mesa/main/stencil.h b/src/mesa/main/stencil.h
index 860a477..b27be16 100644
--- a/src/mesa/main/stencil.h
+++ b/src/mesa/main/stencil.h
@@ -1,10 +1,10 @@
-/* $Id: stencil.h,v 1.4 1999/12/13 04:08:27 joukj Exp $ */
+/* $Id: stencil.h,v 1.5 2000/04/11 20:42:22 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
  * Version:  3.3
  * 
- * Copyright (C) 1999  Brian Paul   All Rights Reserved.
+ * Copyright (C) 1999-2000  Brian Paul   All Rights Reserved.
  * 
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -64,13 +64,13 @@ gl_stencil_and_depth_test_pixels( GLcontext *ctx, GLuint n,
 
 
 extern void
-gl_read_stencil_span( GLcontext *ctx, GLint n, GLint x, GLint y,
-                      GLstencil stencil[] );
+_mesa_read_stencil_span( GLcontext *ctx, GLint n, GLint x, GLint y,
+                         GLstencil stencil[] );
 
 
 extern void
-gl_write_stencil_span( GLcontext *ctx, GLint n, GLint x, GLint y,
-                       const GLstencil stencil[] );
+_mesa_write_stencil_span( GLcontext *ctx, GLint n, GLint x, GLint y,
+                          const GLstencil stencil[] );
 
 
 extern void gl_alloc_stencil_buffer( GLcontext *ctx );
-- 
2.7.4