tgsi: add new tgsi_two_side.c utility code

This could be used by any driver where the device doesn't directly
support two-sided lighting.  This code modifies a fragment shader
to accecpt back-face colors and choose between the front/back colors
depending on the triangle's front-face sign.

1 files changed, 34 insertions, 0 deletions

diff --git a/src/gallium/auxiliary/tgsi/tgsi_two_side.h b/src/gallium/auxiliary/tgsi/tgsi_two_side.h
new file mode 100644
index 00000000000..bac239e41af
--- /dev/null
+++ b/src/gallium/auxiliary/tgsi/tgsi_two_side.h
@@ -0,0 +1,34 @@
+/*
+ * Copyright 2013 VMware, Inc.
+ * 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"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef TGSI_TWO_SIDE_H
+#define TGSI_TWO_SIDE_H
+
+struct tgsi_token;
+
+struct tgsi_token *
+tgsi_add_two_side(const struct tgsi_token *tokens_in);
+
+#endif /* TGSI_TWO_SIDE_H */