reset depth stencil state for render pass (#3230)

include/mbgl/mtl/render_pass.hpp

@@ -42,6 +42,13 @@ public:
 
     void endEncoding();
 
+    /// Resets the states and bindings of the render pass to deal
+    /// with situations where they are changed by calling the
+    /// underlying rendering API directly. Currently this happens
+    /// when a user changes one of these states or bindings
+    /// in a custom layer
+    void resetState();
+
     void addDebugSignpost(const char* name) override;
 
     void bindVertex(const BufferResource&, std::size_t offset, std::size_t index, std::size_t size = 0);

src/mbgl/gfx/drawable_custom_layer_host_tweaker.cpp

@@ -8,6 +8,7 @@
 
 #if MLN_RENDER_BACKEND_METAL
 #include <mbgl/style/layers/mtl/custom_layer_render_parameters.hpp>
+#include <mbgl/mtl/render_pass.hpp>
 #endif
 
 #include <memory>
@@ -23,6 +24,9 @@ void DrawableCustomLayerHostTweaker::execute([[maybe_unused]] gfx::Drawable& dra
                        paintParameters.colorModeForRenderPass());
 
 #if MLN_RENDER_BACKEND_METAL
+    const auto& mtlRenderPass = static_cast<mtl::RenderPass*>(paintParameters.renderPass.get());
+    mtlRenderPass->resetState();
+
     style::mtl::CustomLayerRenderParameters parameters(paintParameters);
 #else
     style::CustomLayerRenderParameters parameters(paintParameters);

src/mbgl/mtl/render_pass.cpp

@@ -72,6 +72,17 @@ void RenderPass::endEncoding() {
     }
 }
 
+void RenderPass::resetState() {
+    currentDepthStencilState.reset();
+    currentStencilReferenceValue = 0;
+    for (int i = 0; i < maxBinds; ++i) {
+        vertexBinds[i].reset();
+        fragmentBinds[i].reset();
+        fragmentTextureBindings[i].reset();
+        fragmentSamplerStates[i].reset();
+    }
+}
+
 namespace {
 constexpr auto missing = "<none>";
 NS::String* toNSString(const char* str) {