Question

假设我有一个Matrix4f matrix，其中填充了我想用点Vec3 translation = new Vec3(2.0f, 1.0f, 0.0f);

翻译的值

下面的公式给出了意想不到的结果，我怎样才能正确地翻译我的矩阵呢？ e.g

Matrix4f result = Utils.translate(matrix, translation);

这是我目前的翻译代码..

public Matrix4f translate(Matrix4f matrix, Vec3 vector) {

    Matrix4f transform = new Matrix4f(new float[][] {
            new float[] { 0, 0, 0, vector.x },
            new float[] { 0, 0, 0, vector.y },
            new float[] { 0, 0, 0, vector.z },
            new float[] { 0, 0, 0, 1 },
    });

    return add(matrix, transform);
}

public Matrix4f add(Matrix4f matrixA, Matrix4f matrixB) {

    Matrix4f matrix = new Matrix4f();

    for (int a = 0; a < matrix.values.length; a++){
        matrix.values[a] = matrixA.values[a] + matrixB.values[a];
    }

    return matrix;
}

public void loadIdentity(Matrix4f matrix) {
    matrix.load(new float[][] {
            new float[] { 1, 0, 0, 0 },
            new float[] { 0, 1, 0, 0 },
            new float[] { 0, 0, 1, 0 },
            new float[] { 0, 0, 0, 1 },
    });
}

这是Matrix4f ..

的定义

public class Matrix4f {

    public float[] values;

    public Matrix4f() {
        this.values = new float[16];
        Utils.loadIdentity(this);
    }

    public Matrix4f(float[] values) {
        this.values = values;
    }

    public Matrix4f(float[][] values) {
        load(values);
    }

    public void load(float[][] values) {
        this.values = new float[] {
            values[0][0], values[0][1], values[0][2], values[0][3],
            values[1][0], values[1][1], values[1][2], values[1][3],
            values[2][0], values[2][1], values[2][2], values[2][3],
            values[3][0], values[3][1], values[3][2], values[3][3]
        };
    }

    public float[] getValues() { 
    return this.values; 
    }
}

Answer 1

public Matrix4f translate(Matrix4f matrix, Vec3 vector) {

    Matrix4f transform = new Matrix4f(new float[][] {
            new float[] { 1, 0, 0, vector.x },
            new float[] { 0, 1, 0, vector.y },
            new float[] { 0, 0, 1, vector.z },
            new float[] { 0, 0, 0, 1 },
    });

    return multiply(matrix, transform);
}

public Matrix4f multiply(Matrix4f matrixA, Matrix4f matrixB) {

    Matrix4f matrix = new Matrix4f(new float[][] {
            new float[] {
                    (matrixA.values[0] * matrixB.values[0]) + (matrixA.values[1] * matrixB.values[4]) + (matrixA.values[2] * matrixB.values[8]) + (matrixA.values[3] * matrixB.values[12]),
                    (matrixA.values[0] * matrixB.values[1]) + (matrixA.values[1] * matrixB.values[5]) + (matrixA.values[2] * matrixB.values[9]) + (matrixA.values[3] * matrixB.values[13]),
                    (matrixA.values[0] * matrixB.values[2]) + (matrixA.values[1] * matrixB.values[6]) + (matrixA.values[2] * matrixB.values[10]) + (matrixA.values[3] * matrixB.values[14]),
                    (matrixA.values[0] * matrixB.values[3]) + (matrixA.values[1] * matrixB.values[7]) + (matrixA.values[2] * matrixB.values[11]) + (matrixA.values[3] * matrixB.values[15])
            },
            new float[] {
                    (matrixA.values[4] * matrixB.values[0]) + (matrixA.values[5] * matrixB.values[4]) + (matrixA.values[6] * matrixB.values[8]) + (matrixA.values[7] * matrixB.values[12]),
                    (matrixA.values[4] * matrixB.values[1]) + (matrixA.values[5] * matrixB.values[5]) + (matrixA.values[6] * matrixB.values[9]) + (matrixA.values[7] * matrixB.values[13]),
                    (matrixA.values[4] * matrixB.values[2]) + (matrixA.values[5] * matrixB.values[6]) + (matrixA.values[6] * matrixB.values[10]) + (matrixA.values[7] * matrixB.values[14]),
                    (matrixA.values[4] * matrixB.values[3]) + (matrixA.values[5] * matrixB.values[7]) + (matrixA.values[6] * matrixB.values[11]) + (matrixA.values[7] * matrixB.values[15])
            },
            new float[] {
                    (matrixA.values[8] * matrixB.values[0]) + (matrixA.values[9] * matrixB.values[4]) + (matrixA.values[10] * matrixB.values[8]) + (matrixA.values[11] * matrixB.values[12]),
                    (matrixA.values[8] * matrixB.values[1]) + (matrixA.values[9] * matrixB.values[5]) + (matrixA.values[10] * matrixB.values[9]) + (matrixA.values[11] * matrixB.values[13]),
                    (matrixA.values[8] * matrixB.values[2]) + (matrixA.values[9] * matrixB.values[6]) + (matrixA.values[10] * matrixB.values[10]) + (matrixA.values[11] * matrixB.values[14]),
                    (matrixA.values[8] * matrixB.values[3]) + (matrixA.values[9] * matrixB.values[7]) + (matrixA.values[10] * matrixB.values[11]) + (matrixA.values[11] * matrixB.values[15])
            },
            new float[] {
                    (matrixA.values[12] * matrixB.values[0]) + (matrixA.values[13] * matrixB.values[4]) + (matrixA.values[14] * matrixB.values[8]) + (matrixA.values[15] * matrixB.values[12]),
                    (matrixA.values[12] * matrixB.values[1]) + (matrixA.values[13] * matrixB.values[5]) + (matrixA.values[14] * matrixB.values[9]) + (matrixA.values[15] * matrixB.values[13]),
                    (matrixA.values[12] * matrixB.values[2]) + (matrixA.values[13] * matrixB.values[6]) + (matrixA.values[14] * matrixB.values[10]) + (matrixA.values[15] * matrixB.values[14]),
                    (matrixA.values[12] * matrixB.values[3]) + (matrixA.values[13] * matrixB.values[7]) + (matrixA.values[14] * matrixB.values[11]) + (matrixA.values[15] * matrixB.values[15])
            }
    });

    return matrix;
}

通过3元素向量执行4x4矩阵的转换

1 个答案: