svga: add work-around for Sauerbraten Z fighting issue

Reviewed-by: Jose Fonseca <[email protected]>

1 files changed, 33 insertions, 0 deletions

diff --git a/src/gallium/drivers/svga/svga_context.c b/src/gallium/drivers/svga/svga_context.c
index 4da9a6551f6..0ba09ce2ebc 100644
--- a/src/gallium/drivers/svga/svga_context.c
+++ b/src/gallium/drivers/svga/svga_context.c
@@ -25,11 +25,13 @@
 
 #include "svga_cmd.h"
 
+#include "os/os_process.h"
 #include "pipe/p_defines.h"
 #include "util/u_inlines.h"
 #include "pipe/p_screen.h"
 #include "util/u_memory.h"
 #include "util/u_bitmask.h"
+#include "util/u_string.h"
 
 #include "svga_context.h"
 #include "svga_screen.h"
@@ -80,6 +82,35 @@ static void svga_destroy( struct pipe_context *pipe )
 }
 
 
+/**
+ * Check the process name to see if we're running with an app that
+ * needs any particular work-arounds.
+ */
+static void
+check_for_workarounds(struct svga_context *svga)
+{
+   char name[1000];
+
+   if (!os_get_process_name(name, sizeof(name)))
+      return;
+
+   if (util_strcmp(name, "sauer_client") == 0) {
+      /*
+       * Sauerbraten uses a two-pass rendering algorithm.  The first pass
+       * draws a depth map.  The second pass draws the colors.  On the second
+       * pass we wind up using the swtnl path because the game tries to use
+       * a GLbyte[3] normal vector array (which the SVGA3D protocol does not
+       * support.)  The vertices of the first and second passes don't quite
+       * match so we see some depth/Z-fighting issues.  This work-around
+       * causes us to map GLbyte[3] to SVGA3D_DECLTYPE_UBYTE4N and avoid the
+       * swtnl path.  Despite not correctly converting normal vectors from
+       * GLbyte[3] to float[4], the rendering looks OK.
+       */
+      debug_printf("Enabling sauerbraten GLbyte[3] work-around\n");
+      svga->workaround.use_decltype_ubyte4n = TRUE;
+   }
+}
+
 
 struct pipe_context *svga_context_create( struct pipe_screen *screen,
 					  void *priv )
@@ -156,6 +187,8 @@ struct pipe_context *svga_context_create( struct pipe_screen *screen,
 
    LIST_INITHEAD(&svga->dirty_buffers);
 
+   check_for_workarounds(svga);
+
    return &svga->pipe;
 
 no_state: