VertexAttribute.java

// Copyright 2021 The Terasology Foundation
// SPDX-License-Identifier: Apache-2.0

package org.terasology.engine.rendering.assets.mesh.vertex;

import org.joml.Vector3f;
import org.joml.Vector3i;
import org.lwjgl.opengl.GL30;

import java.nio.ByteBuffer;

public class VertexAttribute<T> {
    public static final VertexAttribute<Vector3i> VECTOR_3_I_VERTEX_ATTRIBUTE = new VertexAttribute<>(Vector3i.class, (index, buffer, value) -> {
        buffer.putInt(index, value.x);
        buffer.putInt(index + Integer.BYTES, value.y);
        buffer.putInt(index + Integer.BYTES * 2, value.z);
    }, TypeMapping.ATTR_INT, 3);
    public static final VertexAttribute<Vector3f> VECTOR_3_F_VERTEX_ATTRIBUTE = new VertexAttribute<>(
            Vector3f.class, (index, buffer, value) -> {
        buffer.putFloat(index, value.x);
        buffer.putFloat(index + Float.BYTES, value.y);
        buffer.putFloat(index + Float.BYTES * 2, value.z);
    }, TypeMapping.ATTR_FLOAT, 3);

    public enum TypeMapping {
        ATTR_FLOAT(Float.BYTES, GL30.GL_FLOAT),
        ATTR_SHORT(Short.BYTES, GL30.GL_SHORT),
        ATTR_BYTE(Byte.BYTES, GL30.GL_BYTE),
        ATTR_INT(Integer.BYTES, GL30.GL_INT);

        public final int size;
        public final int glType;
        TypeMapping(int size, int glType) {
            this.size = size;
            this.glType = glType;
        }
    }

    interface Mapper<T> {
        void map(int index, ByteBuffer buffer, T value);
    }

    public final Mapper<T> mapper;
    VertexAttribute(Class target, Mapper<T> mapper, TypeMapping mapping, int count) {
        this.mapper = mapper;
    }
}

VertexResource.java

// Copyright 2021 The Terasology Foundation
// SPDX-License-Identifier: Apache-2.0

package org.terasology.engine.rendering.assets.mesh.vertex;

import org.lwjgl.BufferUtils;

import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;

public class VertexResource {
    public final int inStride;
    public final int inSize;
    public final ByteBuffer buffer;
    public VertexAttribute[] attributes;

    protected VertexResource(int inStride, int inSize, VertexAttribute[] attributes) {
        this.inSize = inSize;
        this.inStride = inStride;
        this.buffer = BufferUtils.createByteBuffer(inSize);
    }

    public static class VertexResourceBuilder {
        List<VertexAttribute> attributes = new ArrayList<>();
    }

    public static class VertexAttributeBinding<Y,V extends VertexAttribute<Y>> {
        private V attributes;
        private VertexResource resource;
        private int position = 0;
        private int offset = 0;

        public void put(Y value) {
            attributes.mapper.map(position * resource.inStride + offset, resource.buffer, value);
        }
        public void put(int vertexIndex, Y value) {
            attributes.mapper.map(vertexIndex * resource.inStride + offset, resource.buffer, value);

        }
    }


}