minecraft-src/com/mojang/blaze3d/opengl/VertexArrayCache.java

package com.mojang.blaze3d.opengl;

import com.mojang.blaze3d.vertex.VertexFormat;
import com.mojang.blaze3d.vertex.VertexFormatElement;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import net.fabricmc.api.EnvType;
import net.fabricmc.api.Environment;
import org.jetbrains.annotations.Nullable;
import org.lwjgl.opengl.ARBVertexAttribBinding;
import org.lwjgl.opengl.GLCapabilities;

@Environment(EnvType.CLIENT)
public abstract class VertexArrayCache {
	public static VertexArrayCache create(GLCapabilities capabilities, GlDebugLabel debugLabel, Set<String> enabledExtensions) {
		if (capabilities.GL_ARB_vertex_attrib_binding && GlDevice.USE_GL_ARB_vertex_attrib_binding) {
			enabledExtensions.add("GL_ARB_vertex_attrib_binding");
			return new VertexArrayCache.Separate(debugLabel);
		} else {
			return new VertexArrayCache.Emulated(debugLabel);
		}
	}

	public abstract void bindVertexArray(VertexFormat format, GlBuffer buffer);

	@Environment(EnvType.CLIENT)
	static class Emulated extends VertexArrayCache {
		private final Map<VertexFormat, VertexArrayCache.VertexArray> cache = new HashMap();
		private final GlDebugLabel debugLabels;

		public Emulated(GlDebugLabel debugLabels) {
			this.debugLabels = debugLabels;
		}

		@Override
		public void bindVertexArray(VertexFormat format, GlBuffer buffer) {
			VertexArrayCache.VertexArray vertexArray = (VertexArrayCache.VertexArray)this.cache.get(format);
			if (vertexArray == null) {
				int i = GlStateManager._glGenVertexArrays();
				GlStateManager._glBindVertexArray(i);
				GlStateManager._glBindBuffer(34962, buffer.handle);
				setupCombinedAttributes(format, true);
				VertexArrayCache.VertexArray vertexArray2 = new VertexArrayCache.VertexArray(i, format, buffer);
				this.debugLabels.applyLabel(vertexArray2);
				this.cache.put(format, vertexArray2);
			} else {
				GlStateManager._glBindVertexArray(vertexArray.id);
				if (vertexArray.lastVertexBuffer != buffer) {
					GlStateManager._glBindBuffer(34962, buffer.handle);
					vertexArray.lastVertexBuffer = buffer;
					setupCombinedAttributes(format, false);
				}
			}
		}

		private static void setupCombinedAttributes(VertexFormat vertexFormat, boolean enabled) {
			int i = vertexFormat.getVertexSize();
			List<VertexFormatElement> list = vertexFormat.getElements();

			for (int j = 0; j < list.size(); j++) {
				VertexFormatElement vertexFormatElement = (VertexFormatElement)list.get(j);
				if (enabled) {
					GlStateManager._enableVertexAttribArray(j);
				}

				switch (vertexFormatElement.usage()) {
					case POSITION:
					case GENERIC:
						GlStateManager._vertexAttribPointer(
							j, vertexFormatElement.count(), GlConst.toGl(vertexFormatElement.type()), false, i, vertexFormat.getOffset(vertexFormatElement)
						);
						break;
					case NORMAL:
					case COLOR:
						GlStateManager._vertexAttribPointer(
							j, vertexFormatElement.count(), GlConst.toGl(vertexFormatElement.type()), true, i, vertexFormat.getOffset(vertexFormatElement)
						);
						break;
					case UV:
						if (vertexFormatElement.type() == VertexFormatElement.Type.FLOAT) {
							GlStateManager._vertexAttribPointer(
								j, vertexFormatElement.count(), GlConst.toGl(vertexFormatElement.type()), false, i, vertexFormat.getOffset(vertexFormatElement)
							);
						} else {
							GlStateManager._vertexAttribIPointer(
								j, vertexFormatElement.count(), GlConst.toGl(vertexFormatElement.type()), i, vertexFormat.getOffset(vertexFormatElement)
							);
						}
				}
			}
		}
	}

	@Environment(EnvType.CLIENT)
	static class Separate extends VertexArrayCache {
		private final Map<VertexFormat, VertexArrayCache.VertexArray> cache = new HashMap();
		private final GlDebugLabel debugLabels;

		public Separate(GlDebugLabel debugLabels) {
			this.debugLabels = debugLabels;
		}

		@Override
		public void bindVertexArray(VertexFormat format, GlBuffer buffer) {
			VertexArrayCache.VertexArray vertexArray = (VertexArrayCache.VertexArray)this.cache.get(format);
			if (vertexArray == null) {
				int i = GlStateManager._glGenVertexArrays();
				GlStateManager._glBindVertexArray(i);
				ARBVertexAttribBinding.glBindVertexBuffer(0, buffer.handle, 0L, format.getVertexSize());
				List<VertexFormatElement> list = format.getElements();

				for (int j = 0; j < list.size(); j++) {
					VertexFormatElement vertexFormatElement = (VertexFormatElement)list.get(j);
					GlStateManager._enableVertexAttribArray(j);
					switch (vertexFormatElement.usage()) {
						case POSITION:
						case GENERIC:
							ARBVertexAttribBinding.glVertexAttribFormat(
								j, vertexFormatElement.count(), GlConst.toGl(vertexFormatElement.type()), false, format.getOffset(vertexFormatElement)
							);
							break;
						case NORMAL:
						case COLOR:
							ARBVertexAttribBinding.glVertexAttribFormat(
								j, vertexFormatElement.count(), GlConst.toGl(vertexFormatElement.type()), true, format.getOffset(vertexFormatElement)
							);
							break;
						case UV:
							if (vertexFormatElement.type() == VertexFormatElement.Type.FLOAT) {
								ARBVertexAttribBinding.glVertexAttribFormat(
									j, vertexFormatElement.count(), GlConst.toGl(vertexFormatElement.type()), false, format.getOffset(vertexFormatElement)
								);
							} else {
								ARBVertexAttribBinding.glVertexAttribIFormat(
									j, vertexFormatElement.count(), GlConst.toGl(vertexFormatElement.type()), format.getOffset(vertexFormatElement)
								);
							}
					}

					ARBVertexAttribBinding.glVertexAttribBinding(j, 0);
				}

				VertexArrayCache.VertexArray vertexArray2 = new VertexArrayCache.VertexArray(i, format, buffer);
				this.debugLabels.applyLabel(vertexArray2);
				this.cache.put(format, vertexArray2);
			} else {
				GlStateManager._glBindVertexArray(vertexArray.id);
				if (vertexArray.lastVertexBuffer != buffer) {
					if (vertexArray.lastVertexBuffer != null && vertexArray.lastVertexBuffer.handle == buffer.handle) {
						ARBVertexAttribBinding.glBindVertexBuffer(0, 0, 0L, 0);
					}

					ARBVertexAttribBinding.glBindVertexBuffer(0, buffer.handle, 0L, format.getVertexSize());
					vertexArray.lastVertexBuffer = buffer;
				}
			}
		}
	}

	@Environment(EnvType.CLIENT)
	public static class VertexArray {
		final int id;
		final VertexFormat format;
		@Nullable
		GlBuffer lastVertexBuffer;

		VertexArray(int id, VertexFormat format, @Nullable GlBuffer lastVertexBuffer) {
			this.id = id;
			this.format = format;
			this.lastVertexBuffer = lastVertexBuffer;
		}
	}
}