minecraft-src/com/mojang/blaze3d/pipeline/MainTarget.java

package com.mojang.blaze3d.pipeline;

import com.google.common.collect.ImmutableList;
import com.mojang.blaze3d.platform.GlStateManager;
import com.mojang.blaze3d.platform.TextureUtil;
import com.mojang.blaze3d.systems.RenderSystem;
import java.util.List;
import java.util.Objects;
import net.fabricmc.api.EnvType;
import net.fabricmc.api.Environment;

@Environment(EnvType.CLIENT)
public class MainTarget extends RenderTarget {
	public static final int DEFAULT_WIDTH = 854;
	public static final int DEFAULT_HEIGHT = 480;
	static final MainTarget.Dimension DEFAULT_DIMENSIONS = new MainTarget.Dimension(854, 480);

	public MainTarget(int width, int height) {
		super(true);
		this.createFrameBuffer(width, height);
	}

	private void createFrameBuffer(int width, int height) {
		MainTarget.Dimension dimension = this.allocateAttachments(width, height);
		this.frameBufferId = GlStateManager.glGenFramebuffers();
		GlStateManager._glBindFramebuffer(36160, this.frameBufferId);
		GlStateManager._bindTexture(this.colorTextureId);
		GlStateManager._texParameter(3553, 10241, 9728);
		GlStateManager._texParameter(3553, 10240, 9728);
		GlStateManager._texParameter(3553, 10242, 33071);
		GlStateManager._texParameter(3553, 10243, 33071);
		GlStateManager._glFramebufferTexture2D(36160, 36064, 3553, this.colorTextureId, 0);
		GlStateManager._bindTexture(this.depthBufferId);
		GlStateManager._texParameter(3553, 34892, 0);
		GlStateManager._texParameter(3553, 10241, 9728);
		GlStateManager._texParameter(3553, 10240, 9728);
		GlStateManager._texParameter(3553, 10242, 33071);
		GlStateManager._texParameter(3553, 10243, 33071);
		GlStateManager._glFramebufferTexture2D(36160, 36096, 3553, this.depthBufferId, 0);
		GlStateManager._bindTexture(0);
		this.viewWidth = dimension.width;
		this.viewHeight = dimension.height;
		this.width = dimension.width;
		this.height = dimension.height;
		this.checkStatus();
		GlStateManager._glBindFramebuffer(36160, 0);
	}

	private MainTarget.Dimension allocateAttachments(int width, int height) {
		RenderSystem.assertOnRenderThreadOrInit();
		this.colorTextureId = TextureUtil.generateTextureId();
		this.depthBufferId = TextureUtil.generateTextureId();
		MainTarget.AttachmentState attachmentState = MainTarget.AttachmentState.NONE;

		for (MainTarget.Dimension dimension : MainTarget.Dimension.listWithFallback(width, height)) {
			attachmentState = MainTarget.AttachmentState.NONE;
			if (this.allocateColorAttachment(dimension)) {
				attachmentState = attachmentState.with(MainTarget.AttachmentState.COLOR);
			}

			if (this.allocateDepthAttachment(dimension)) {
				attachmentState = attachmentState.with(MainTarget.AttachmentState.DEPTH);
			}

			if (attachmentState == MainTarget.AttachmentState.COLOR_DEPTH) {
				return dimension;
			}
		}

		throw new RuntimeException("Unrecoverable GL_OUT_OF_MEMORY (allocated attachments = " + attachmentState.name() + ")");
	}

	private boolean allocateColorAttachment(MainTarget.Dimension dimension) {
		RenderSystem.assertOnRenderThreadOrInit();
		GlStateManager._getError();
		GlStateManager._bindTexture(this.colorTextureId);
		GlStateManager._texImage2D(3553, 0, 32856, dimension.width, dimension.height, 0, 6408, 5121, null);
		return GlStateManager._getError() != 1285;
	}

	private boolean allocateDepthAttachment(MainTarget.Dimension dimension) {
		RenderSystem.assertOnRenderThreadOrInit();
		GlStateManager._getError();
		GlStateManager._bindTexture(this.depthBufferId);
		GlStateManager._texImage2D(3553, 0, 6402, dimension.width, dimension.height, 0, 6402, 5126, null);
		return GlStateManager._getError() != 1285;
	}

	@Environment(EnvType.CLIENT)
	static enum AttachmentState {
		NONE,
		COLOR,
		DEPTH,
		COLOR_DEPTH;

		private static final MainTarget.AttachmentState[] VALUES = values();

		MainTarget.AttachmentState with(MainTarget.AttachmentState otherState) {
			return VALUES[this.ordinal() | otherState.ordinal()];
		}
	}

	@Environment(EnvType.CLIENT)
	static class Dimension {
		public final int width;
		public final int height;

		Dimension(int width, int height) {
			this.width = width;
			this.height = height;
		}

		static List<MainTarget.Dimension> listWithFallback(int width, int height) {
			RenderSystem.assertOnRenderThreadOrInit();
			int i = RenderSystem.maxSupportedTextureSize();
			return width > 0 && width <= i && height > 0 && height <= i
				? ImmutableList.of(new MainTarget.Dimension(width, height), MainTarget.DEFAULT_DIMENSIONS)
				: ImmutableList.of(MainTarget.DEFAULT_DIMENSIONS);
		}

		public boolean equals(Object object) {
			if (this == object) {
				return true;
			} else if (object != null && this.getClass() == object.getClass()) {
				MainTarget.Dimension dimension = (MainTarget.Dimension)object;
				return this.width == dimension.width && this.height == dimension.height;
			} else {
				return false;
			}
		}

		public int hashCode() {
			return Objects.hash(new Object[]{this.width, this.height});
		}

		public String toString() {
			return this.width + "x" + this.height;
		}
	}
}