Create geometry renderer

src/main/java/org/geysermc/packgenerator/mapping/geometry/GeometryRenderer.java

@@ -0,0 +1,75 @@
+package org.geysermc.packgenerator.mapping.geometry;
+
+import com.mojang.blaze3d.buffers.GpuBuffer;
+import com.mojang.blaze3d.platform.NativeImage;
+import com.mojang.blaze3d.systems.CommandEncoder;
+import com.mojang.blaze3d.systems.RenderSystem;
+import com.mojang.blaze3d.textures.GpuTexture;
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.gui.navigation.ScreenRectangle;
+import net.minecraft.client.gui.render.pip.OversizedItemRenderer;
+import net.minecraft.client.gui.render.state.GuiItemRenderState;
+import net.minecraft.client.gui.render.state.GuiRenderState;
+import net.minecraft.client.gui.render.state.pip.OversizedItemRenderState;
+import net.minecraft.client.renderer.item.TrackingItemStackRenderState;
+import net.minecraft.world.item.ItemDisplayContext;
+import net.minecraft.world.item.ItemStack;
+import org.geysermc.packgenerator.mixin.PictureInPictureRendererAccessor;
+import org.geysermc.packgenerator.render.PictureInPictureCopyRenderer;
+import org.joml.Matrix3x2fStack;
+
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.Objects;
+
+public class GeometryRenderer {
+
+    public static void render(ItemStack stack, Path path) {
+        TrackingItemStackRenderState itemRenderState = new TrackingItemStackRenderState();
+        Minecraft.getInstance().getItemModelResolver().updateForTopItem(itemRenderState, stack, ItemDisplayContext.GUI, null, null, 0);
+        itemRenderState.setOversizedInGui(true);
+
+        GuiItemRenderState guiItemRenderState = new GuiItemRenderState("geometry_render", new Matrix3x2fStack(16), itemRenderState, 0, 0, null);
+        ScreenRectangle sizeBounds = guiItemRenderState.oversizedItemBounds();
+        Objects.requireNonNull(sizeBounds);
+        OversizedItemRenderState oversizedRenderState = new OversizedItemRenderState(guiItemRenderState, sizeBounds.left(), sizeBounds.top(), sizeBounds.right() + 4, sizeBounds.bottom() + 4);
+
+        try (OversizedItemRenderer itemRenderer = new OversizedItemRenderer(Minecraft.getInstance().renderBuffers().bufferSource())) {
+            //noinspection DataFlowIssue
+            ((PictureInPictureCopyRenderer) itemRenderer).geyser_mappings_generator$allowTextureCopy();
+            itemRenderer.prepare(oversizedRenderState, new GuiRenderState(), 4);
+            writeAsPNG(path, ((PictureInPictureRendererAccessor) itemRenderer).getTexture());
+        }
+    }
+
+    // Simplified TextureUtil#writeAsPNG with some modifications to flip the image and just generate it at full size
+    private static void writeAsPNG(Path path, GpuTexture texture) {
+        RenderSystem.assertOnRenderThread();
+        int width = texture.getWidth(0);
+        int height = texture.getHeight(0);
+        int bufferSize = texture.getFormat().pixelSize() * width * height;
+
+        GpuBuffer buffer = RenderSystem.getDevice().createBuffer(() -> "Texture output buffer", GpuBuffer.USAGE_COPY_DST | GpuBuffer.USAGE_MAP_READ, bufferSize);
+        CommandEncoder commandEncoder = RenderSystem.getDevice().createCommandEncoder();
+
+        Runnable writer = () -> {
+            try (GpuBuffer.MappedView mappedView = commandEncoder.mapBuffer(buffer, true, false)) {
+                try (NativeImage nativeImage = new NativeImage(width, height, false)) {
+                    for (int y = 0; y < height; y++) {
+                        for (int x = 0; x < width; x++) {
+                            int colour = mappedView.data().getInt((x + y * width) * texture.getFormat().pixelSize());
+                            nativeImage.setPixelABGR(x, height - y - 1, colour);
+                        }
+                    }
+
+                    nativeImage.writeToFile(path);
+                } catch (IOException var19) {
+                    // TODO
+                }
+            }
+
+            buffer.close();
+        };
+        commandEncoder.copyTextureToBuffer(texture, buffer, 0, writer, 0);
+    }
+}

src/main/java/org/geysermc/packgenerator/mixin/GuiItemRenderStateMixin.java

@@ -0,0 +1,16 @@
+package org.geysermc.packgenerator.mixin;
+
+import net.minecraft.client.gui.render.state.GuiItemRenderState;
+import net.minecraft.client.gui.render.state.ScreenArea;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.Constant;
+import org.spongepowered.asm.mixin.injection.ModifyConstant;
+
+@Mixin(GuiItemRenderState.class)
+public abstract class GuiItemRenderStateMixin implements ScreenArea {
+
+    @ModifyConstant(method = "calculateOversizedItemBounds", constant = @Constant(intValue = 16))
+    public int neverReturnNull(int i) {
+        return -1;
+    }
+}

src/main/java/org/geysermc/packgenerator/mixin/PictureInPictureRendererAccessor.java

@@ -0,0 +1,13 @@
+package org.geysermc.packgenerator.mixin;
+
+import com.mojang.blaze3d.textures.GpuTexture;
+import net.minecraft.client.gui.render.pip.PictureInPictureRenderer;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.gen.Accessor;
+
+@Mixin(PictureInPictureRenderer.class)
+public interface PictureInPictureRendererAccessor {
+
+    @Accessor
+    GpuTexture getTexture();
+}

src/main/java/org/geysermc/packgenerator/mixin/PictureInPictureRendererMixin.java

@@ -0,0 +1,34 @@
+package org.geysermc.packgenerator.mixin;
+
+import com.mojang.blaze3d.textures.GpuTexture;
+import net.minecraft.client.gui.render.pip.PictureInPictureRenderer;
+import org.geysermc.packgenerator.render.PictureInPictureCopyRenderer;
+import org.jetbrains.annotations.Nullable;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.Unique;
+import org.spongepowered.asm.mixin.injection.Constant;
+import org.spongepowered.asm.mixin.injection.ModifyConstant;
+
+@Mixin(PictureInPictureRenderer.class)
+public abstract class PictureInPictureRendererMixin implements AutoCloseable, PictureInPictureCopyRenderer {
+
+    @Shadow
+    private @Nullable GpuTexture texture;
+
+    @Unique
+    private boolean allowTextureCopy = false;
+
+    @Override
+    public void geyser_mappings_generator$allowTextureCopy() {
+        if (texture != null) {
+            throw new IllegalStateException("texture already created");
+        }
+        allowTextureCopy = true;
+    }
+
+    @ModifyConstant(method = "prepareTexturesAndProjection", constant = @Constant(intValue = 12))
+    public int allowUsageCopySrc(int usage) {
+        return allowTextureCopy ? usage | GpuTexture.USAGE_COPY_SRC : usage;
+    }
+}

src/main/java/org/geysermc/packgenerator/render/PictureInPictureCopyRenderer.java

@@ -0,0 +1,6 @@
+package org.geysermc.packgenerator.render;
+
+public interface PictureInPictureCopyRenderer {
+
+    void geyser_mappings_generator$allowTextureCopy();
+}

src/main/resources/geyser-mappings-generator.mixins.json

@@ -9,7 +9,10 @@
     "BlockModelWrapperMixin$UnbakedMixin",
     "ConditionalItemModelAccessor",
     "EntityRenderDispatcherAccessor",
+    "GuiItemRenderStateMixin",
     "ModelManagerMixin",
+    "PictureInPictureRendererAccessor",
+    "PictureInPictureRendererMixin",
     "SelectItemModelAccessor",
     "SelectItemModelMixin",
     "SelectItemModelMixin$UnbakedSwitchMixin",