util: add a function which converts 2D coordinates to cubemap coordinates

The code was taken over from u_gen_mipmap.

1 files changed, 102 insertions, 0 deletions

diff --git a/src/gallium/auxiliary/util/u_texture.c b/src/gallium/auxiliary/util/u_texture.c
new file mode 100644
index 00000000000..cd477ab640f
--- /dev/null
+++ b/src/gallium/auxiliary/util/u_texture.c
@@ -0,0 +1,102 @@
+/**************************************************************************
+ *
+ * Copyright 2008 Tungsten Graphics, Inc., Cedar Park, Texas.
+ * All Rights Reserved.
+ * Copyright 2008 VMware, Inc.  All rights reserved.
+ * Copyright 2009 Marek Olšák <[email protected]>
+ *
+ * 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 TUNGSTEN GRAPHICS 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.
+ *
+ **************************************************************************/
+
+/**
+ * @file
+ * Texture mapping utility functions.
+ *
+ * @author Brian Paul
+ *         Marek Olšák
+ */
+
+#include "pipe/p_defines.h"
+
+#include "util/u_texture.h"
+
+void util_map_texcoords2d_onto_cubemap(unsigned face,
+                                       const float *in_st, unsigned in_stride,
+                                       float *out_str, unsigned out_stride)
+{
+   int i;
+   float rx, ry, rz;
+
+   /* loop over quad verts */
+   for (i = 0; i < 4; i++) {
+      /* Compute sc = +/-scale and tc = +/-scale.
+       * Not +/-1 to avoid cube face selection ambiguity near the edges,
+       * though that can still sometimes happen with this scale factor...
+       */
+      const float scale = 0.9999f;
+      const float sc = (2 * in_st[0] - 1) * scale;
+      const float tc = (2 * in_st[1] - 1) * scale;
+
+      switch (face) {
+         case PIPE_TEX_FACE_POS_X:
+            rx = 1;
+            ry = -tc;
+            rz = -sc;
+            break;
+         case PIPE_TEX_FACE_NEG_X:
+            rx = -1;
+            ry = -tc;
+            rz = sc;
+            break;
+         case PIPE_TEX_FACE_POS_Y:
+            rx = sc;
+            ry = 1;
+            rz = tc;
+            break;
+         case PIPE_TEX_FACE_NEG_Y:
+            rx = sc;
+            ry = -1;
+            rz = -tc;
+            break;
+         case PIPE_TEX_FACE_POS_Z:
+            rx = sc;
+            ry = -tc;
+            rz = 1;
+            break;
+         case PIPE_TEX_FACE_NEG_Z:
+            rx = -sc;
+            ry = -tc;
+            rz = -1;
+            break;
+         default:
+            rx = ry = rz = 0;
+            assert(0);
+      }
+
+      out_str[0] = rx; /*s*/
+      out_str[1] = ry; /*t*/
+      out_str[2] = rz; /*r*/
+
+      in_st += in_stride;
+      out_str += out_stride;
+   }
+}