LWJGL教程09 - 世界

世界矩阵

$$
M = M_p(M_tM_rM_s)
= M_pM_w
$$

创建一个Transformation类。

[imports ...]

public class Transformation {
    private Matrix4f projectionMatrix;
    private Matrix4f worldMatrix;

    public Transformation() {
        worldMatrix = new Matrix4f();
        projectionMatrix = new Matrix4f();
    }

    public Matrix4f getProjectionMatrix(float fov, float width, float height, float zNear, float zFar) {
        float aspectRatio = width / height;
        projectionMatrix.identity();
        projectionMatrix.perspective(fov, aspectRatio, zNear, zFar);
        return projectionMatrix;
    }

    public Matrix4f getWorldMatrix(Vector3f offset, Vector3f rotation, float scale) {
        worldMatrix.identity().translate(offset).
                rotateX((float)Math.toRadians(rotation.x)).
                rotateY((float)Math.toRadians(rotation.y)).
                rotateZ((float)Math.toRadians(rotation.z)).
                scale(scale);
        return worldMatrix;
    }
}

在创建一个Entity。

[imports ...]

public class Entity {
    private Mesh mesh;
    private Vector3f position;
    private Vector3f rotation;
    private float scale;

    public Entity(Mesh mesh) {
        this.mesh = mesh;
        position = new Vector3f();
        rotation = new Vector3f();
        scale = 1;
    }
    [Getter & Setter ...]
}

然后在SceneRender中实例化Transformation和添加Uniforms。

public SceneRender() {
    shaderProgram = new ShaderProgram();
    transformation = new Transformation();
    [...]
    uniforms.createUniform("worldMatrix");
}

在修改一下Scene.render()。

public void render(Scene scene) {
    shaderProgram.bind();

    // 更新投影矩阵
    Matrix4f projectionMatrix = transformation.getProjectionMatrix(Projection.FOV, Window.getWidth(), Window.getHeight(), Projection.Z_NEAR, Projection.Z_FAR);
    uniforms.setUniform("projectionMatrix", projectionMatrix);

    scene.getEntities().forEach(entity -> {
        Matrix4f worldMatrix =
                transformation.getWorldMatrix(
                        entity.getPosition(),
                        entity.getRotation(),
                        entity.getScale());
        uniforms.setUniform("worldMatrix", worldMatrix);
        // 为该游戏项渲染网格
        entity.getMesh().render();
    });

    // 还原状态
    glBindVertexArray(0);

    shaderProgram.unbind();
}

在Mesh中添加render()。

public void render() {
    // 绑定VAO
    glBindVertexArray(getVaoId());

    // 绘制顶点
    glDrawElements(GL_TRIANGLES, getVerticesCount(), GL_UNSIGNED_INT, 0);
}

再修改一下顶点着色器。

#version 330

layout (location=0) in vec3 position;
layout (location=1) in vec3 inColour;

out vec3 exColour;

uniform mat4 worldMatrix;
uniform mat4 projectionMatrix;

void main()
{
    gl_Position = projectionMatrix * worldMatrix * vec4(position, 1.0);
    exColour = inColour;
}

最后再ILogic中添加update()，并在渲染前调用。

测试一下。

import com.game.*;
import org.lwjgl.glfw.GLFW;
import org.lwjgl.system.MemoryUtil;

import java.nio.FloatBuffer;

import static org.lwjgl.opengl.GL30.*;

public class TestLogic implements ILogic {

    Entity entity;

    @Override
    public void init() {
        float[] vertices = new float[] {
                // VO
                -0.5f,  0.5f,  0.5f,
                // V1
                -0.5f, -0.5f,  0.5f,
                // V2
                0.5f, -0.5f,  0.5f,
                // V3
                0.5f,  0.5f,  0.5f,
                // V4
                -0.5f,  0.5f, -0.5f,
                // V5
                0.5f,  0.5f, -0.5f,
                // V6
                -0.5f, -0.5f, -0.5f,
                // V7
                0.5f, -0.5f, -0.5f,
        };

        float[] colors = new float[]{
                0.5f, 0.0f, 0.0f,
                0.0f, 0.5f, 0.0f,
                0.0f, 0.0f, 0.5f,
                0.0f, 0.5f, 0.5f,
                0.5f, 0.0f, 0.0f,
                0.0f, 0.5f, 0.0f,
                0.0f, 0.0f, 0.5f,
                0.0f, 0.5f, 0.5f,
        };
        int[] indices = new int[] {
                // 前面
                0, 1, 3, 3, 1, 2,
                // 上面
                4, 0, 3, 5, 4, 3,
                // 右面
                3, 2, 7, 5, 3, 7,
                // 左面
                6, 1, 0, 6, 0, 4,
                // 下面
                2, 1, 6, 2, 6, 7,
                // 后面
                7, 6, 4, 7, 4, 5,
        };

        Mesh mesh = new Mesh(vertices, colors, indices);
        entity = new Entity(mesh);
        entity.setPosition(0, 0, -2);
        Engine.scene.addEntity(entity);
    }

    @Override
    public void update() {
        // 更新旋转角
        float rotation = entity.getRotation().x + 1.5f;
        if ( rotation > 360 ) {
            rotation = 0;
        }
        entity.setRotation(rotation, rotation, rotation);
    }
    
	[...]
}