From ac5d3525f383a95f269fad82f01dc5bd7fbedddb Mon Sep 17 00:00:00 2001
From: Julius Trinkunas <smilediver@outlook.com>
Date: Thu, 14 Nov 2024 20:20:47 +0200
Subject: [PATCH] Metal: enable mipmap support

---
 core/renderer/backend/Types.h             |  3 +++
 core/renderer/backend/metal/TextureMTL.mm | 23 ++++++++++++++++++++---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/core/renderer/backend/Types.h b/core/renderer/backend/Types.h
index a19455f4896b..f1433922e7e0 100644
--- a/core/renderer/backend/Types.h
+++ b/core/renderer/backend/Types.h
@@ -46,6 +46,9 @@ inline TargetBufferFlags getMRTColorFlag(size_t index) noexcept
 
 typedef TargetBufferFlags ClearFlag;
 
+/// @note In Metal, mipmap filter is derived from `magFilter` value: ie `NEAREST_MIPMAP_LINEAR` and
+///     `LINEAR_MIPMAP_LINEAR` will select `LINEAR` filter, while `NEAREST_MIPMAP_NEAREST` and
+///     `LINEAR_MIPMAP_NEAREST` will select `NEAREST` filter.
 struct SamplerDescriptor
 {
     SamplerFilter magFilter         = SamplerFilter::LINEAR;
diff --git a/core/renderer/backend/metal/TextureMTL.mm b/core/renderer/backend/metal/TextureMTL.mm
index 042d820b3c25..d142cde57450 100644
--- a/core/renderer/backend/metal/TextureMTL.mm
+++ b/core/renderer/backend/metal/TextureMTL.mm
@@ -32,7 +32,7 @@ of this software and associated documentation files (the "Software"), to deal
 
 namespace
 {
-MTLSamplerAddressMode toMTLSamplerAddressMode(SamplerAddressMode mode)
+static MTLSamplerAddressMode toMTLSamplerAddressMode(SamplerAddressMode mode)
 {
     MTLSamplerAddressMode ret = MTLSamplerAddressModeRepeat;
     switch (mode)
@@ -53,7 +53,7 @@ MTLSamplerAddressMode toMTLSamplerAddressMode(SamplerAddressMode mode)
     return ret;
 }
 
-MTLSamplerMinMagFilter toMTLSamplerMinMagFilter(SamplerFilter mode)
+static MTLSamplerMinMagFilter toMTLSamplerMinMagFilter(SamplerFilter mode)
 {
     switch (mode)
     {
@@ -70,7 +70,22 @@ MTLSamplerMinMagFilter toMTLSamplerMinMagFilter(SamplerFilter mode)
     }
 }
 
-bool isColorRenderable(PixelFormat textureFormat)
+static MTLSamplerMipFilter toMTLSamplerMipFilter(SamplerFilter mode)
+{
+    switch (mode)
+    {
+    case SamplerFilter::NEAREST_MIPMAP_LINEAR:
+    case SamplerFilter::LINEAR_MIPMAP_LINEAR:
+        return MTLSamplerMipFilterLinear;
+    case SamplerFilter::NEAREST_MIPMAP_NEAREST:
+    case SamplerFilter::LINEAR_MIPMAP_NEAREST:
+        return MTLSamplerMipFilterNearest;
+    default:
+        return MTLSamplerMipFilterNotMipmapped;
+    }
+}
+
+static bool isColorRenderable(PixelFormat textureFormat)
 {
     switch (textureFormat)
     {
@@ -168,6 +183,8 @@ bool isColorRenderable(PixelFormat textureFormat)
         descriptor.minFilter == SamplerFilter::DONT_CARE ? _minFilter : toMTLSamplerMinMagFilter(descriptor.minFilter);
     mtlDescriptor.magFilter =
         descriptor.magFilter == SamplerFilter::DONT_CARE ? _magFilter : toMTLSamplerMinMagFilter(descriptor.magFilter);
+    mtlDescriptor.mipFilter =
+        descriptor.magFilter == SamplerFilter::DONT_CARE ? _mipFilter : toMTLSamplerMipFilter(descriptor.magFilter);
 
     if (_mtlSamplerState)
     {