Unify Iris integrations

Iris now has built-in support for NeoForge, so we can use the same
integration on both.

We also re-enable Forge's client tests, and test Iris there too.

Fixes #1967

projects/common/src/client/java/dan200/computercraft/client/integration/IrisShaderMod.java

@@ -0,0 +1,63 @@
+// SPDX-FileCopyrightText: 2022 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.client.integration;
+
+import com.google.auto.service.AutoService;
+import com.mojang.blaze3d.vertex.VertexFormat;
+import dan200.computercraft.client.render.RenderTypes;
+import dan200.computercraft.client.render.text.DirectFixedWidthFontRenderer;
+import dan200.computercraft.shared.platform.PlatformHelper;
+import net.irisshaders.iris.api.v0.IrisApi;
+import net.irisshaders.iris.api.v0.IrisTextVertexSink;
+import net.minecraft.util.FastColor;
+
+import java.nio.ByteBuffer;
+import java.util.Optional;
+import java.util.function.IntFunction;
+
+@AutoService(ShaderMod.Provider.class)
+public class IrisShaderMod implements ShaderMod.Provider {
+    @Override
+    public Optional<ShaderMod> get() {
+        return PlatformHelper.get().isModLoaded("iris") ? Optional.of(new Impl()) : Optional.empty();
+    }
+
+    private static final class Impl extends ShaderMod {
+        @Override
+        public boolean isRenderingShadowPass() {
+            return IrisApi.getInstance().isRenderingShadowPass();
+        }
+
+        @Override
+        public DirectFixedWidthFontRenderer.QuadEmitter getQuadEmitter(int vertexCount, IntFunction<ByteBuffer> makeBuffer) {
+            return IrisApi.getInstance().getMinorApiRevision() >= 1
+                ? new IrisQuadEmitter(vertexCount, makeBuffer)
+                : super.getQuadEmitter(vertexCount, makeBuffer);
+        }
+
+        private static final class IrisQuadEmitter implements DirectFixedWidthFontRenderer.QuadEmitter {
+            private final IrisTextVertexSink sink;
+
+            private IrisQuadEmitter(int vertexCount, IntFunction<ByteBuffer> makeBuffer) {
+                sink = IrisApi.getInstance().createTextVertexSink(vertexCount, makeBuffer);
+            }
+
+            @Override
+            public VertexFormat format() {
+                return sink.getUnderlyingVertexFormat();
+            }
+
+            @Override
+            public ByteBuffer buffer() {
+                return sink.getUnderlyingByteBuffer();
+            }
+
+            @Override
+            public void quad(float x1, float y1, float x2, float y2, float z, int colour, float u1, float v1, float u2, float v2) {
+                sink.quad(x1, y1, x2, y2, z, FastColor.ABGR32.fromArgb32(colour), u1, v1, u2, v2, RenderTypes.FULL_BRIGHT_LIGHTMAP);
+            }
+        }
+    }
+}

projects/common/src/main/java/dan200/computercraft/shared/platform/PlatformHelper.java

@@ -60,6 +60,14 @@ public interface PlatformHelper {
         return instance == null ? Services.raise(PlatformHelper.class, Instance.ERROR) : instance;
     }
 
+    /**
+     * Determine if the specified mod is loaded.
+     *
+     * @param id The id of the mod to check.
+     * @return Whether this mod is loaded.
+     */
+    boolean isModLoaded(String id);
+
     /**
      * Create a new config builder.
      *

projects/common/src/test/java/dan200/computercraft/TestPlatformHelper.java

@@ -49,6 +49,11 @@ import java.util.function.Predicate;
 
 @AutoService({ PlatformHelper.class, ComputerCraftAPIService.class })
 public class TestPlatformHelper extends AbstractComputerCraftAPI implements PlatformHelper {
+    @Override
+    public boolean isModLoaded(String id) {
+        return false;
+    }
+
     @Override
     public ConfigFile.Builder createConfigBuilder() {
         throw new UnsupportedOperationException("Cannot create config file inside tests");