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1/*
2 * Copyright 2022 Google LLC
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#include "experimental/graphite/src/mtl/MtlSampler.h"
9
10#include "experimental/graphite/src/mtl/MtlCaps.h"
11#include "experimental/graphite/src/mtl/MtlGpu.h"
12#include "include/core/SkSamplingOptions.h"
13
14namespace skgpu::mtl {
15
16Sampler::Sampler(const Gpu* gpu,
17                 sk_cfp<id<MTLSamplerState>> samplerState)
18        : skgpu::Sampler(gpu)
19        , fSamplerState(std::move(samplerState)) {}
20
21static inline MTLSamplerAddressMode tile_mode_to_mtl_sampler_address(SkTileMode tileMode,
22                                                                     const Caps& caps) {
23    switch (tileMode) {
24        case SkTileMode::kClamp:
25            return MTLSamplerAddressModeClampToEdge;
26        case SkTileMode::kRepeat:
27            return MTLSamplerAddressModeRepeat;
28        case SkTileMode::kMirror:
29            return MTLSamplerAddressModeMirrorRepeat;
30        case SkTileMode::kDecal:
31            // For this tilemode, we should have checked that clamp-to-border support exists.
32            // If it doesn't we should have fallen back to a shader instead.
33            // TODO: for textures with alpha, we could use ClampToZero if there's no
34            // ClampToBorderColor as they'll clamp to (0,0,0,0).
35            // Unfortunately textures without alpha end up clamping to (0,0,0,1).
36            if (@available(macOS 10.12, iOS 14.0, *)) {
37                SkASSERT(caps.clampToBorderSupport());
38                return MTLSamplerAddressModeClampToBorderColor;
39            } else {
40                SkASSERT(false);
41                return MTLSamplerAddressModeClampToZero;
42            }
43    }
44    SkUNREACHABLE;
45}
46
47sk_sp<Sampler> Sampler::Make(const Gpu* gpu,
48                             const SkSamplingOptions& samplingOptions,
49                             SkTileMode xTileMode,
50                             SkTileMode yTileMode) {
51    sk_cfp<MTLSamplerDescriptor*> desc([[MTLSamplerDescriptor alloc] init]);
52
53    MTLSamplerMinMagFilter minMagFilter = [&] {
54        switch (samplingOptions.filter) {
55            case SkFilterMode::kNearest: return MTLSamplerMinMagFilterNearest;
56            case SkFilterMode::kLinear:  return MTLSamplerMinMagFilterLinear;
57        }
58        SkUNREACHABLE;
59    }();
60
61    MTLSamplerMipFilter mipFilter = [&] {
62      switch (samplingOptions.mipmap) {
63          case SkMipmapMode::kNone:    return MTLSamplerMipFilterNotMipmapped;
64          case SkMipmapMode::kNearest: return MTLSamplerMipFilterNearest;
65          case SkMipmapMode::kLinear:  return MTLSamplerMipFilterLinear;
66      }
67      SkUNREACHABLE;
68    }();
69
70    auto samplerDesc = [[MTLSamplerDescriptor alloc] init];
71    samplerDesc.rAddressMode = MTLSamplerAddressModeClampToEdge;
72    samplerDesc.sAddressMode = tile_mode_to_mtl_sampler_address(xTileMode, gpu->mtlCaps());
73    samplerDesc.tAddressMode = tile_mode_to_mtl_sampler_address(yTileMode, gpu->mtlCaps());
74    samplerDesc.magFilter = minMagFilter;
75    samplerDesc.minFilter = minMagFilter;
76    samplerDesc.mipFilter = mipFilter;
77    samplerDesc.lodMinClamp = 0.0f;
78    samplerDesc.lodMaxClamp = FLT_MAX;  // default value according to docs.
79    samplerDesc.maxAnisotropy = 1.0f;
80    samplerDesc.normalizedCoordinates = true;
81    if (@available(macOS 10.11, iOS 9.0, *)) {
82        samplerDesc.compareFunction = MTLCompareFunctionNever;
83    }
84#ifdef SK_ENABLE_MTL_DEBUG_INFO
85    // TODO: add label?
86#endif
87
88    sk_cfp<id<MTLSamplerState>> sampler([gpu->device() newSamplerStateWithDescriptor:desc.get()]);
89    if (!sampler) {
90        return nullptr;
91    }
92    return sk_sp<Sampler>(new Sampler(gpu, std::move(sampler)));
93}
94
95void Sampler::onFreeGpuData() {
96    fSamplerState.reset();
97}
98
99} // namespace skgpu::mtl
100
101