Mesa (master): radv: Use TRUNC_COORD on samplers

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Module: Mesa
Branch: master
Commit: 58f25098a0dc4f4976dadacdc4e7a9db42ec0c50
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=58f25098a0dc4f4976dadacdc4e7a9db42ec0c50

Author: Joshua Ashton <joshua at froggi.es>
Date:   Tue Feb 25 19:24:15 2020 +0000

radv: Use TRUNC_COORD on samplers

The default behaviour (0) is: "round-nearest-even to n.6 and drop fraction when point sampling" whereas the Vulkan spec simply wants us to floor it (1) "truncate when point sampling".

See 15.6.1 in the Vulkan spec.
https://www.khronos.org/registry/vulkan/specs/1.2-extensions/html/vkspec.html#textures-normalized-operations

The Direct3D spec also mandates this (https://microsoft.github.io/DirectX-Specs/d3d/archive/D3D11_3_FunctionalSpec.htm#7.18.7%20Point%20Sample%20Addressing)

This fixes some point-sampling texture precision issues in some Direct3D 9 titles such as Guild Wars 2 and htoL#NiQ: The Firefly Diary that are not present on other vendors.

Fixes dEQP-VK.pipeline.sampler.exact_sampling.*

https://github.com/Joshua-Ashton/d9vk/issues/450
https://github.com/doitsujin/dxvk/issues/1433

CC: <mesa-stable at lists.freedesktop.org>

Reviewed-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3951>

---

 src/amd/vulkan/radv_device.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/amd/vulkan/radv_device.c b/src/amd/vulkan/radv_device.c
index 8e4fc861722..4bfcbb1c0ba 100644
--- a/src/amd/vulkan/radv_device.c
+++ b/src/amd/vulkan/radv_device.c
@@ -7054,6 +7054,7 @@ radv_init_sampler(struct radv_device *device,
 			   device->physical_device->rad_info.chip_class == GFX9;
 	unsigned filter_mode = V_008F30_SQ_IMG_FILTER_MODE_BLEND;
 	unsigned depth_compare_func = V_008F30_SQ_TEX_DEPTH_COMPARE_NEVER;
+	bool trunc_coord = pCreateInfo->minFilter == VK_FILTER_NEAREST && pCreateInfo->magFilter == VK_FILTER_NEAREST;
 
 	const struct VkSamplerReductionModeCreateInfo *sampler_reduction =
 		vk_find_struct_const(pCreateInfo->pNext,
@@ -7074,7 +7075,8 @@ radv_init_sampler(struct radv_device *device,
 			     S_008F30_ANISO_BIAS(max_aniso_ratio) |
 			     S_008F30_DISABLE_CUBE_WRAP(0) |
 			     S_008F30_COMPAT_MODE(compat_mode) |
-			     S_008F30_FILTER_MODE(filter_mode));
+			     S_008F30_FILTER_MODE(filter_mode) |
+			     S_008F30_TRUNC_COORD(trunc_coord));
 	sampler->state[1] = (S_008F34_MIN_LOD(S_FIXED(CLAMP(pCreateInfo->minLod, 0, 15), 8)) |
 			     S_008F34_MAX_LOD(S_FIXED(CLAMP(pCreateInfo->maxLod, 0, 15), 8)) |
 			     S_008F34_PERF_MIP(max_aniso_ratio ? max_aniso_ratio + 6 : 0));