Lines are hard

- Add BoundingBoxComponent for drawing entity bounding boxes.
- Render lines with a wireframe material.
- Add viewport size and default line width uniforms.

src/main/java/com/jozufozu/flywheel/backend/engine/uniform/FrameUniforms.java

@@ -7,11 +7,12 @@ import com.jozufozu.flywheel.api.event.RenderContext;
 import com.jozufozu.flywheel.api.visualization.VisualizationManager;
 import com.jozufozu.flywheel.lib.math.MatrixMath;
 
+import net.minecraft.client.Minecraft;
 import net.minecraft.core.Vec3i;
 import net.minecraft.world.phys.Vec3;
 
 public class FrameUniforms implements UniformProvider {
-	public static final int SIZE = 220;
+	public static final int SIZE = 232;
 
 	private RenderContext context;
 
@@ -51,10 +52,17 @@ public class FrameUniforms implements UniformProvider {
 		writeVec3(ptr + 176, lookVector.x, lookVector.y, lookVector.z);
 
 		writeVec2(ptr + 192, camera.getXRot(), camera.getYRot());
+		var window = Minecraft.getInstance()
+				.getWindow();
 
-		MemoryUtil.memPutInt(ptr + 200, getConstantAmbientLightFlag(context));
+		writeVec2(ptr + 200, window.getWidth(), window.getHeight());
 
-		writeTime(ptr + 204);
+		// default line width: net.minecraft.client.renderer.RenderStateShard.LineStateShard
+		MemoryUtil.memPutFloat(ptr + 208, Math.max(2.5F, (float) window.getWidth() / 1920.0F * 2.5F));
+
+		MemoryUtil.memPutInt(ptr + 212, getConstantAmbientLightFlag(context));
+
+		writeTime(ptr + 216);
 	}
 
 	private void writeTime(long ptr) {

src/main/java/com/jozufozu/flywheel/lib/material/StandardMaterialShaders.java

@@ -10,6 +10,8 @@ public final class StandardMaterialShaders {
 			Flywheel.rl("material/default.vert"),
 			Flywheel.rl("material/default.frag")));
 
+	public static final MaterialShaders WIREFRAME = MaterialShaders.REGISTRY.registerAndGet(new SimpleMaterialShaders(Flywheel.rl("material/wireframe.vert"), Flywheel.rl("material/wireframe.frag")));
+
 	private StandardMaterialShaders() {
 	}
 

src/main/java/com/jozufozu/flywheel/lib/visual/AbstractEntityVisual.java

@@ -35,6 +35,7 @@ public abstract class AbstractEntityVisual<T extends Entity> extends AbstractVis
 	protected final EntityVisibilityTester visibilityTester;
 	protected final ShadowComponent shadow;
 	protected final FireComponent fire;
+	protected final BoundingBoxComponent boundingBox;
 
 	public AbstractEntityVisual(VisualizationContext ctx, T entity) {
 		super(ctx, entity.level());
@@ -42,6 +43,7 @@ public abstract class AbstractEntityVisual<T extends Entity> extends AbstractVis
 		visibilityTester = new EntityVisibilityTester(entity, ctx.renderOrigin(), 1.5f);
 		shadow = new ShadowComponent(ctx, entity);
 		fire = new FireComponent(ctx, entity);
+		boundingBox = new BoundingBoxComponent(ctx, entity);
 	}
 
 	@Override
@@ -96,5 +98,6 @@ public abstract class AbstractEntityVisual<T extends Entity> extends AbstractVis
 	protected void _delete() {
 		shadow.delete();
 		fire.delete();
+		boundingBox.delete();
 	}
 }

src/main/java/com/jozufozu/flywheel/lib/visual/BoundingBoxComponent.java

@@ -0,0 +1,170 @@
+package com.jozufozu.flywheel.lib.visual;
+
+import org.joml.Vector4f;
+import org.joml.Vector4fc;
+
+import com.jozufozu.flywheel.api.material.Material;
+import com.jozufozu.flywheel.api.model.Model;
+import com.jozufozu.flywheel.api.vertex.MutableVertexList;
+import com.jozufozu.flywheel.api.visual.VisualFrameContext;
+import com.jozufozu.flywheel.api.visualization.VisualizationContext;
+import com.jozufozu.flywheel.lib.instance.InstanceTypes;
+import com.jozufozu.flywheel.lib.instance.TransformedInstance;
+import com.jozufozu.flywheel.lib.material.SimpleMaterial;
+import com.jozufozu.flywheel.lib.material.StandardMaterialShaders;
+import com.jozufozu.flywheel.lib.math.MoreMath;
+import com.jozufozu.flywheel.lib.model.QuadMesh;
+import com.jozufozu.flywheel.lib.model.SingleMeshModel;
+
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.renderer.LightTexture;
+import net.minecraft.util.Mth;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.entity.LivingEntity;
+
+public class BoundingBoxComponent {
+	private static final Material MATERIAL = SimpleMaterial.builder()
+			.shaders(StandardMaterialShaders.WIREFRAME)
+			.backfaceCulling(false)
+			.build();
+	private static final Model MODEL = new SingleMeshModel(BoundingBoxMesh.INSTANCE, MATERIAL);
+
+	private final VisualizationContext context;
+	private final Entity entity;
+
+	private boolean showEyeBox;
+
+	private final InstanceRecycler<TransformedInstance> recycler;
+
+	public BoundingBoxComponent(VisualizationContext context, Entity entity) {
+		this.context = context;
+		this.entity = entity;
+		this.showEyeBox = entity instanceof LivingEntity;
+
+		this.recycler = new InstanceRecycler<>(this::createInstance);
+	}
+
+	private TransformedInstance createInstance() {
+		TransformedInstance instance = context.instancerProvider()
+				.instancer(InstanceTypes.TRANSFORMED, MODEL)
+				.createInstance();
+		instance.setBlockLight(LightTexture.block(LightTexture.FULL_BLOCK));
+		instance.setChanged();
+		return instance;
+	}
+
+	public void showEyeBox(boolean renderEyeBox) {
+		this.showEyeBox = renderEyeBox;
+	}
+
+	public void beginFrame(VisualFrameContext context) {
+		recycler.resetCount();
+
+		var shouldRenderHitBoxes = Minecraft.getInstance()
+				.getEntityRenderDispatcher()
+				.shouldRenderHitBoxes();
+		if (shouldRenderHitBoxes && !entity.isInvisible() && !Minecraft.getInstance()
+				.showOnlyReducedInfo()) {
+			double entityX = Mth.lerp(context.partialTick(), entity.xOld, entity.getX());
+			double entityY = Mth.lerp(context.partialTick(), entity.yOld, entity.getY());
+			double entityZ = Mth.lerp(context.partialTick(), entity.zOld, entity.getZ());
+
+			var bbWidth = entity.getBbWidth();
+			var bbHeight = entity.getBbHeight();
+			var bbWidthHalf = bbWidth * 0.5;
+			recycler.get()
+					.loadIdentity()
+					.translate(entityX - bbWidthHalf, entityY, entityZ - bbWidthHalf)
+					.scale(bbWidth, bbHeight, bbWidth)
+					.setChanged();
+
+			// TODO: multipart entities and view vectors
+
+			if (showEyeBox) {
+				recycler.get()
+						.loadIdentity()
+						.translate(entityX - bbWidthHalf, entityY + entity.getEyeHeight() - 0.01, entityZ - bbWidthHalf)
+						.scale(bbWidth, 0.02f, bbWidth)
+						.setColor(255, 0, 0)
+						.setChanged();
+			}
+		}
+
+		recycler.discardExtra();
+	}
+
+	public void delete() {
+		recycler.delete();
+	}
+
+	private static class BoundingBoxMesh implements QuadMesh {
+		private static final BoundingBoxMesh INSTANCE = new BoundingBoxMesh();
+		private static final Vector4fc BOUNDING_SPHERE = new Vector4f(0.5f, 0.5f, 0.5f, MoreMath.SQRT_3_OVER_2);
+
+		private BoundingBoxMesh() {
+		}
+
+		@Override
+		public int vertexCount() {
+			return 24;
+		}
+
+		@Override
+		public void write(MutableVertexList vertexList) {
+			// very cursed, maybe we should use vanilla ModelParts instead?
+			writeVertex(vertexList, 0, 0, 0, 0, 0, 0);
+			writeVertex(vertexList, 1, 1, 0, 0, 1, 0);
+			writeVertex(vertexList, 2, 1, 1, 0, 1, 1);
+			writeVertex(vertexList, 3, 0, 1, 0, 0, 1);
+
+			writeVertex(vertexList, 4, 0, 0, 1, 0, 0);
+			writeVertex(vertexList, 5, 0, 0, 0, 1, 0);
+			writeVertex(vertexList, 6, 0, 1, 0, 1, 1);
+			writeVertex(vertexList, 7, 0, 1, 1, 0, 1);
+
+			writeVertex(vertexList, 8, 0, 1, 0, 0, 0);
+			writeVertex(vertexList, 9, 1, 1, 0, 1, 0);
+			writeVertex(vertexList, 10, 1, 1, 1, 1, 1);
+			writeVertex(vertexList, 11, 0, 1, 1, 0, 1);
+
+			writeVertex(vertexList, 12, 1, 0, 1, 0, 0);
+			writeVertex(vertexList, 13, 0, 0, 1, 1, 0);
+			writeVertex(vertexList, 14, 0, 1, 1, 1, 1);
+			writeVertex(vertexList, 15, 1, 1, 1, 0, 1);
+
+			writeVertex(vertexList, 16, 1, 0, 0, 0, 0);
+			writeVertex(vertexList, 17, 1, 0, 1, 1, 0);
+			writeVertex(vertexList, 18, 1, 1, 1, 1, 1);
+			writeVertex(vertexList, 19, 1, 1, 0, 0, 1);
+
+			writeVertex(vertexList, 20, 0, 0, 0, 0, 0);
+			writeVertex(vertexList, 21, 1, 0, 0, 1, 0);
+			writeVertex(vertexList, 22, 1, 0, 1, 1, 1);
+			writeVertex(vertexList, 23, 0, 0, 1, 0, 1);
+		}
+
+		@Override
+		public Vector4fc boundingSphere() {
+			return BOUNDING_SPHERE;
+		}
+
+		@Override
+		public void delete() {
+		}
+
+		private static void writeVertex(MutableVertexList vertexList, int i, float x, float y, float z, float u, float v) {
+			vertexList.x(i, x);
+			vertexList.y(i, y);
+			vertexList.z(i, z);
+			vertexList.r(i, 1);
+			vertexList.g(i, 1);
+			vertexList.b(i, 1);
+			vertexList.u(i, u);
+			vertexList.v(i, v);
+			vertexList.light(i, LightTexture.FULL_BRIGHT);
+			vertexList.normalX(i, 0);
+			vertexList.normalY(i, 1);
+			vertexList.normalZ(i, 0);
+		}
+	}
+}

src/main/java/com/jozufozu/flywheel/vanilla/MinecartVisual.java

@@ -111,6 +111,7 @@ public class MinecartVisual<T extends AbstractMinecart> extends AbstractEntityVi
 	public void beginFrame(VisualFrameContext context) {
 		shadow.beginFrame(context);
 		fire.beginFrame(context);
+		boundingBox.beginFrame(context);
 
 		if (!isVisible(context.frustum())) {
 			return;

src/main/resources/assets/flywheel/flywheel/internal/uniforms/frame.glsl

@@ -15,6 +15,10 @@ layout(std140) uniform _FlwFrameUniforms {
     vec4 flw_cameraPos;
     vec4 flw_cameraLook;
     vec2 flw_cameraRot;
+
+    vec2 flw_viewportSize;
+    float flw_defaultLineWidth;
+
     uint flw_constantAmbientLight;
 
     uint flw_ticks;

src/main/resources/assets/flywheel/flywheel/material/wireframe.frag

@@ -0,0 +1,10 @@
+void flw_materialFragment() {
+    float closestEdge = min(flw_vertexTexCoord.s, min(flw_vertexTexCoord.t, min(1. - flw_vertexTexCoord.s, 1. - flw_vertexTexCoord.t)));
+
+    // multiply by fwidth to get the width of the edge in screen space
+    if (flw_defaultLineWidth * fwidth(closestEdge) < closestEdge) {
+        discard;
+    }
+
+    flw_fragColor = flw_vertexColor;
+}

src/main/resources/assets/flywheel/flywheel/material/wireframe.vert

@@ -0,0 +1,2 @@
+void flw_materialVertex() {
+}