Mesa (master): anv: Handle clamping of inverted depth ranges

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Module: Mesa
Branch: master
Commit: 1d5e1882f662fb4a922353ea272c1e94398f9155
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=1d5e1882f662fb4a922353ea272c1e94398f9155

Author: Jason Ekstrand <jason at jlekstrand.net>
Date:   Tue Jul  7 11:08:31 2020 -0500

anv: Handle clamping of inverted depth ranges

Tested-by: Mike Blumenkrantz <michael.blumenkrantz at gmail.com>
Reviewed-by: Ivan Briano <ivan.briano at intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5792>

---

 src/intel/vulkan/gen8_cmd_buffer.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/intel/vulkan/gen8_cmd_buffer.c b/src/intel/vulkan/gen8_cmd_buffer.c
index fe136ecd928..f2497231fea 100644
--- a/src/intel/vulkan/gen8_cmd_buffer.c
+++ b/src/intel/vulkan/gen8_cmd_buffer.c
@@ -104,9 +104,17 @@ gen8_cmd_buffer_emit_depth_viewport(struct anv_cmd_buffer *cmd_buffer,
    for (uint32_t i = 0; i < count; i++) {
       const VkViewport *vp = &viewports[i];
 
+      /* From the Vulkan spec:
+       *
+       *    "It is valid for minDepth to be greater than or equal to
+       *    maxDepth."
+       */
+      float min_depth = MIN2(vp->minDepth, vp->maxDepth);
+      float max_depth = MAX2(vp->minDepth, vp->maxDepth);
+
       struct GENX(CC_VIEWPORT) cc_viewport = {
-         .MinimumDepth = depth_clamp_enable ? vp->minDepth : 0.0f,
-         .MaximumDepth = depth_clamp_enable ? vp->maxDepth : 1.0f,
+         .MinimumDepth = depth_clamp_enable ? min_depth : 0.0f,
+         .MaximumDepth = depth_clamp_enable ? max_depth : 1.0f,
       };
 
       GENX(CC_VIEWPORT_pack)(NULL, cc_state.map + i * 8, &cc_viewport);