gallium/util: add helper to compute zmin/zmax for a viewport state

Signed-off-by: Ilia Mirkin <[email protected]>
Reviewed-by: Roland Scheidegger <[email protected]>
Cc: "11.2 12.0" <[email protected]>

1 files changed, 59 insertions, 0 deletions

diff --git a/src/gallium/auxiliary/util/u_viewport.h b/src/gallium/auxiliary/util/u_viewport.h
new file mode 100644
index 00000000000..a731b34b8fb
--- /dev/null
+++ b/src/gallium/auxiliary/util/u_viewport.h
@@ -0,0 +1,59 @@
+/**************************************************************************
+ *
+ * Copyright 2016 Ilia Mirkin.
+ * 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 VMWARE 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 U_VIEWPORT_H
+#define U_VIEWPORT_H
+
+#include "c99_compat.h"
+#include "pipe/p_state.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+static inline void
+util_viewport_zmin_zmax(const struct pipe_viewport_state *vp, bool halfz,
+                        float *zmin, float *zmax)
+{
+   float a, b;
+   if (halfz) {
+      a = vp->translate[2];
+      b = vp->translate[2] + vp->scale[2];
+   } else {
+      a = vp->translate[2] - vp->scale[2];
+      b = vp->translate[2] + vp->scale[2];
+   }
+
+   *zmin = a < b ? a : b;
+   *zmax = a < b ? b : a;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif