src/game/java/net/minecraft/client/renderer/debug/CollisionBoxRenderer.java

package net.minecraft.client.renderer.debug;

import com.google.common.collect.ImmutableList;
import com.mojang.blaze3d.vertex.PoseStack;
import com.mojang.blaze3d.vertex.VertexConsumer;
import java.util.Collections;
import java.util.List;
import net.minecraft.Util;
import net.minecraft.client.Minecraft;
import net.minecraft.client.renderer.MultiBufferSource;
import net.minecraft.client.renderer.RenderType;
import net.minecraft.world.entity.Entity;
import net.minecraft.world.phys.shapes.VoxelShape;
import net.minecraftforge.api.distmarker.Dist;
import net.minecraftforge.api.distmarker.OnlyIn;

@OnlyIn(Dist.CLIENT)
public class CollisionBoxRenderer implements DebugRenderer.SimpleDebugRenderer {
    private final Minecraft minecraft;
    private double lastUpdateTime = Double.MIN_VALUE;
    private List<VoxelShape> shapes = Collections.emptyList();

    public CollisionBoxRenderer(Minecraft p_113404_) {
        this.minecraft = p_113404_;
    }

    @Override
    public void render(PoseStack p_113408_, MultiBufferSource p_113409_, double p_113410_, double p_113411_, double p_113412_) {
        double d0 = (double)Util.getNanos();
        if (d0 - this.lastUpdateTime > 1.0E8) {
            this.lastUpdateTime = d0;
            Entity entity = this.minecraft.gameRenderer.getMainCamera().getEntity();
            this.shapes = ImmutableList.copyOf(entity.level().getCollisions(entity, entity.getBoundingBox().inflate(6.0)));
        }

        VertexConsumer vertexconsumer = p_113409_.getBuffer(RenderType.lines());

        for (VoxelShape voxelshape : this.shapes) {
            DebugRenderer.renderVoxelShape(p_113408_, vertexconsumer, voxelshape, -p_113410_, -p_113411_, -p_113412_, 1.0F, 1.0F, 1.0F, 1.0F, true);
        }
    }
}