Unify samplte state anisotropy range (axmolengine#2959)

Author: halx99

axmol/rhi/RHITypes.h

@@ -379,7 +379,7 @@ struct SamplerDesc
     SamplerAddressMode tAddressMode : 2 = SamplerAddressMode::CLAMP;
     SamplerAddressMode wAddressMode : 2 = SamplerAddressMode::CLAMP;
     CompareFunc compareFunc : 4         = CompareFunc::NEVER;
-    uint32_t anisotropy : 4             = 1;
+    uint32_t anisotropy : 4             = 0;
     uint32_t reserved : 12              = 0;
 };
 static_assert(sizeof(SamplerDesc) == 4, "incompatible type: SamplerDesc");

axmol/rhi/SamplerCache.cpp

@@ -194,7 +194,7 @@ void SamplerCache::createBuiltinSamplers()
         d.minFilter  = SamplerFilter::MIN_ANISOTROPIC;
         d.magFilter  = SamplerFilter::MAG_LINEAR;
         d.mipFilter  = SamplerFilter::MIP_LINEAR;
-        d.anisotropy = 16;
+        d.anisotropy = 0xF;
 
         d.sAddressMode = SamplerAddressMode::CLAMP;
         createBuiltinSampler(SamplerIndex::AnisoClamp, d);

axmol/rhi/d3d11/Driver11.cpp

@@ -342,7 +342,7 @@ SamplerHandle DriverImpl::createSampler(const SamplerDesc& desc)
     if (desc.minFilter == SamplerFilter::MIN_ANISOTROPIC)
     {
         sd.Filter        = D3D11_FILTER_ANISOTROPIC;
-        sd.MaxAnisotropy = desc.anisotropy ? desc.anisotropy : 1;
+        sd.MaxAnisotropy = std::clamp(desc.anisotropy + 1u, 1u, 16u);
     }
     else
     {

axmol/rhi/d3d12/Driver12.cpp

@@ -613,7 +613,7 @@ SamplerHandle DriverImpl::createSampler(const SamplerDesc& desc)
         else
             sd.Filter = D3D12_FILTER_ANISOTROPIC;
 
-        sd.MaxAnisotropy = desc.anisotropy ? desc.anisotropy : 1;
+        sd.MaxAnisotropy = std::clamp(desc.anisotropy + 1u, 1u, 16u);
     }
     else
     {

axmol/rhi/metal/DriverMTL.mm

@@ -568,7 +568,7 @@ bool supportS3TC(FeatureSet featureSet)
     samplerDesc.compareFunction = toMTLCompareFunc(desc.compareFunc);
 
     // --- Anisotropy ---
-    samplerDesc.maxAnisotropy = std::clamp(desc.anisotropy, 1u, 16u);
+    samplerDesc.maxAnisotropy = std::clamp(desc.anisotropy + 1u, 1u, 16u);
 
     // --- Create Sampler ---
     id<MTLSamplerState> sampler = [_mtlDevice newSamplerStateWithDescriptor:samplerDesc];

axmol/rhi/opengl/DriverGL.cpp

@@ -167,6 +167,13 @@ DriverImpl::DriverImpl()
     //     supported");
     // }
 
+#ifdef GL_TEXTURE_MAX_ANISOTROPY_EXT
+    if (hasExtension("GL_EXT_texture_filter_anisotropic"))
+    {
+        glGetFloatv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &_cap.maxAnisotropy);
+    }
+#endif
+
     // default FBO
     glGetIntegerv(GL_FRAMEBUFFER_BINDING, &_defaultFBO);
 
@@ -334,20 +341,11 @@ SamplerHandle DriverImpl::createSampler(const SamplerDesc& desc)
     }
 
     // --- Anisotropy ---
-#ifdef GL_TEXTURE_MAX_ANISOTROPY_EXT
-    if (desc.anisotropy > 1)
+    if (desc.anisotropy > 0 && _cap.maxAnisotropy > 1.0f)
     {
-        GLfloat aniso    = static_cast<GLfloat>(desc.anisotropy);
-        GLfloat maxAniso = 0.0f;
-        glGetFloatv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &maxAniso);
-        if (maxAniso > 0.0f)
-        {
-            if (aniso > maxAniso)
-                aniso = maxAniso;
-            glSamplerParameterf(sampler, GL_TEXTURE_MAX_ANISOTROPY_EXT, aniso);
-        }
+        GLfloat aniso = std::clamp(static_cast<GLfloat>(desc.anisotropy + 1), 1.0f, _cap.maxAnisotropy);
+        glSamplerParameterf(sampler, GL_TEXTURE_MAX_ANISOTROPY_EXT, aniso);
     }
-#endif
 
     return reinterpret_cast<SamplerHandle>(static_cast<uintptr_t>(sampler));
 }

axmol/rhi/opengl/DriverGL.h

@@ -41,6 +41,7 @@ struct DriverCapImpl
     bool textureCompressionAstc{false};
     bool textureCompressionEtc2{false};
     bool vertexAttribBinding{false};
+    float maxAnisotropy{0.0f};
 };
 
 /**

axmol/rhi/vulkan/DriverVK.cpp

@@ -588,7 +588,7 @@ SamplerHandle DriverImpl::createSampler(const SamplerDesc& desc)
 
     // Anisotropy
     info.anisotropyEnable = (desc.minFilter == SamplerFilter::MIN_ANISOTROPIC) ? VK_TRUE : VK_FALSE;
-    info.maxAnisotropy    = (desc.anisotropy > 0 ? static_cast<float>(desc.anisotropy) : 1.0f);
+    info.maxAnisotropy    = static_cast<float>(std::clamp(desc.anisotropy + 1u, 1u, 16u));
 
     info.borderColor             = VK_BORDER_COLOR_INT_OPAQUE_BLACK;
     info.unnormalizedCoordinates = VK_FALSE;