OpenGL Java Matrix4f实现

时间:2016-03-22 15:19:10

标签: opengl lwjgl linear-algebra

我试图编写一个4 * 4浮点矩阵类来创建一个包含模型,视图和投影矩阵的3D空间。在我尝试旋转视图矩阵的当前状态下,它似乎也应用了平移,并且空间变形(就像它被挤压一样)。投影,视图和模型矩阵乘法在顶点着色器中完成。

Edit5:转换函数的无效状态如下:

public class Mat4f {
public float m00, m10, m20, m30,
             m01, m11, m21, m31,
             m02, m12, m22, m32,
             m03, m13, m23, m33;

public Mat4f() {
    loadIdentity();
}

public Mat4f loadIdentity() {
    m00 = 1.0f; m10 = 0.0f; m20 = 0.0f; m30 = 0.0f;
    m01 = 0.0f; m11 = 1.0f; m21 = 0.0f; m31 = 0.0f;
    m02 = 0.0f; m12 = 0.0f; m22 = 1.0f; m32 = 0.0f;
    m03 = 0.0f; m13 = 0.0f; m23 = 0.0f; m33 = 1.0f;
    return this;
}

public Mat4f store(FloatBuffer buffer) {
    buffer.put(m00);
    buffer.put(m01);
    buffer.put(m02);
    buffer.put(m03);

    buffer.put(m10);
    buffer.put(m11);
    buffer.put(m12);
    buffer.put(m13);

    buffer.put(m20);
    buffer.put(m21);
    buffer.put(m22);
    buffer.put(m23);

    buffer.put(m30);
    buffer.put(m31);
    buffer.put(m32);
    buffer.put(m33);

    buffer.flip();

    return this;
}

public Mat4f loadPerspective(float fov, float ratio, float near, float far) {
    m11 = (float) (1.0f / (Math.tan(fov / 2.0f)));
    m00 = m11 / ratio;
    m22 = -(far + near) / (far - near);
    m23 = -1.0f;
    m32 = -2.0f * far * near / (far - near);
    m33 = 0.0f;
    return this;
}

public Mat4f translate(float x, float y, float z) {
    m30 = x;
    m31 = y;
    m32 = z;
    return this;
}

public Mat4f scale(float x, float y, float z) {
    m00 = x;
    m11 = y;
    m22 = z;
    return this;
}

public Mat4f rotateX(float x) {
    m11 = (float) Math.cos(x);
    m12 = (float) Math.sin(x);
    m21 = (float) -(Math.sin(x));
    m22 = (float) Math.cos(x);
    return this;
}

public Mat4f rotateY(float y) {
    m00 = (float) Math.cos(y);
    m02 = (float) -(Math.sin(y));
    m20 = (float) Math.sin(y);
    m22 = (float) Math.cos(y);
    return this;
}

public Mat4f rotateZ(float z) {
    m00 = (float) Math.cos(z);
    m01 = (float) Math.sin(z);
    m10 = (float) -(Math.sin(z));
    m11 = (float) Math.cos(z);
    return this;
}
}

正确的做法如下:

public Mat4f translate(float x, float y, float z, Mat4f dest) {
    dest.m00 = m00;
    dest.m01 = m01;
    dest.m02 = m02;
    dest.m03 = m03;
    dest.m10 = m10;
    dest.m11 = m11;
    dest.m12 = m12;
    dest.m13 = m13;
    dest.m20 = m20;
    dest.m21 = m21;
    dest.m22 = m22;
    dest.m23 = m23;
    dest.m30 = m00 * x + m10 * y + m20 * z + m30;
    dest.m31 = m01 * x + m11 * y + m21 * z + m31;
    dest.m32 = m02 * x + m12 * y + m22 * z + m32;
    dest.m33 = m03 * x + m13 * y + m23 * z + m33;
    return this;
}

public Mat4f translate(float x, float y, float z) {
    return translate(x, y, z, this);
}

public Mat4f scale(float x, float y, float z, Mat4f dest) {
    dest.m00 = m00 * x;
    dest.m01 = m01 * x;
    dest.m02 = m02 * x;
    dest.m03 = m03 * x;
    dest.m10 = m10 * y;
    dest.m11 = m11 * y;
    dest.m12 = m12 * y;
    dest.m13 = m13 * y;
    dest.m20 = m20 * z;
    dest.m21 = m21 * z;
    dest.m22 = m22 * z;
    dest.m23 = m23 * z;
    dest.m30 = m30;
    dest.m31 = m31;
    dest.m32 = m32;
    dest.m33 = m33;
    return this;
}

public Mat4f scale(float x, float y, float z) {
    return scale(x, y, z, this);
}

public Mat4f rotateX(float x, Mat4f dest) {
    float cos = (float) Math.cos(x);
    float sin = (float) Math.sin(x);
    float rm11 = cos;
    float rm12 = sin;
    float rm21 = -sin;
    float rm22 = cos;

    float nm10 = m10 * rm11 + m20 * rm12;
    float nm11 = m11 * rm11 + m21 * rm12;
    float nm12 = m12 * rm11 + m22 * rm12;
    float nm13 = m13 * rm11 + m23 * rm12;

    dest. m20 = m10 * rm21 + m20 * rm22;
    dest.m21 = m11 * rm21 + m21 * rm22;
    dest.m22 = m12 * rm21 + m22 * rm22;
    dest. m23 = m13 * rm21 + m23 * rm22;

    dest.m10 = nm10;
    dest.m11 = nm11;
    dest.m12 = nm12;
    dest.m13 = nm13;

    return this;
}

public Mat4f rotateX(float x) {
    return rotateX(x, this);
}

public Mat4f rotateY(float y, Mat4f dest) {
    float cos = (float) Math.cos(y);
    float sin = (float) Math.sin(y);
    float rm00 = cos;
    float rm02 = -sin;
    float rm20 = sin;
    float rm22 = cos;

    float nm00 = m00 * rm00 + m20 * rm02;
    float nm01 = m01 * rm00 + m21 * rm02;
    float nm02 = m02 * rm00 + m22 * rm02;
    float nm03 = m03 * rm00 + m23 * rm02;

    dest.m20 = m00 * rm20 + m20 * rm22;
    dest.m21 = m01 * rm20 + m21 * rm22;
    dest.m22 = m02 * rm20 + m22 * rm22;
    dest.m23 = m03 * rm20 + m23 * rm22;

    dest.m00 = nm00;
    dest.m01 = nm01;
    dest.m02 = nm02;
    dest.m03 = nm03;

    return this;
}

public Mat4f rotateY(float y) {
    return rotateY(y, this);
}

public Mat4f rotateZ(float z, Mat4f dest) {
    float cos = (float) Math.cos(z);
    float sin = (float) Math.sin(z);
    float rm00 = cos;
    float rm01 = sin;
    float rm10 = -sin;
    float rm11 = cos;

    float nm00 = m00 * rm00 + m10 * rm01;
    float nm01 = m01 * rm00 + m11 * rm01;
    float nm02 = m02 * rm00 + m12 * rm01;
    float nm03 = m03 * rm00 + m13 * rm01;

    dest.m10 = m00 * rm10 + m10 * rm11;
    dest.m11 = m01 * rm10 + m11 * rm11;
    dest.m12 = m02 * rm10 + m12 * rm11;
    dest.m13 = m03 * rm10 + m13 * rm11;

    dest.m00 = nm00;
    dest.m01 = nm01;
    dest.m02 = nm02;
    dest.m03 = nm03;

    return this;
}

public Mat4f rotateZ(float z) {
    return rotateZ(z, this);
}

为了修改矩阵,我使用了以下转换顺序:

public void transform() {
    mMat.loadIdentity();
    mMat.translate(position.x, position.y, position.z);
    mMat.rotateX((float) Math.toRadians(orientation.x));
    mMat.rotateY((float) Math.toRadians(orientation.y));
    mMat.rotateZ((float) Math.toRadians(orientation.z));
    mMat.scale(scale.x, scale.y, scale.z);
}

public void updateCamera() {
    Vec3f position = World.camera.getPosition();
    vMat.loadIdentity();
    vMat.rotateX((float) Math.toRadians(World.camera.getPitch()));
    vMat.rotateY((float) Math.toRadians(World.camera.getYaw()));
    vMat.translate(-position.x, -position.y, position.z);
}

编辑:透视投影很好,翻译也是如此,但是如果我将模型矩阵存储在Mat4f中,那么模型'旋转跟随相机的一个。

Edit2:当我使用Mat4f作为模型矩阵时,模型的方向不再跟随相机旋转。投影矩阵,平移和缩放效果很好。

Edit3:编辑了代码,应用的旋转不是一个完整的圆周旋转,模型左右摆动。

Edit4:我试图用矩阵乘法

进行旋转

2 个答案:

答案 0 :(得分:0)

您的矩阵类不实现转换的组合。每个矩阵方法只需覆盖某些元素。

例如,查看以下操作顺序:

translate(1,1,1);
rotateX(45);
translate(1,1,1);

这样的数学序列应该由矩阵乘法T * R * T表示(其中T和R是具有相应参数的基本平移/旋转矩阵)。

但是,你的代码所做的只是创建T(因为最初,矩阵是标识),覆盖一些部分进行旋转,最后再次覆盖翻译部分。

要修复代码,您需要实现适当的矩阵乘法方法,并且只要您想对矩阵应用进一步的转换,就可以使用它。为基本转换矩阵创建一些方法可能会有所帮助。

但是,这仍然看起来像通常的行主要与列主要矩阵存储布局顺序给我。

您的mXY成员布局建议您使用数学约定,其中m12将是第二行,第三列。然后,您的store方法会将矩阵放入具有列主要布局的缓冲区中。这种缓冲区可以由传统GL的矩阵函数(如glLoadMatrixglMultMatrix)直接使用。它也将是"标准"矩阵制服的布局,其中transpose参数设置为GL_FALSE

但是,查看您的translate方法:

public Mat4f translate(float x, float y, float z) {
    m30 = x;
    m31 = y;
    m32 = z;
   return this;
}

这会将翻译向量设置为最后一个,而不是最后一个。 (所有其他功能似乎也使用转置布局)。

现在旧版GL使用matrix * vector约定(而不是D3D更喜欢的vector * matrix)。在这种情况下,您的矩阵将转换为GL期望的内容。如果使用着色器,则由您使用的乘法顺序决定 - 但它必须与您用于矩阵的约定相匹配,并且M * v == v^T * M^T

答案 1 :(得分:0)

问题确实是我没有考虑早先的转变。我最终没有使用矩阵乘法。我复制了JOML中的相关部分,您可以访问:https://github.com/JOML-CI/JOML。 我将编辑问题以反映问题所在,以及该类的最终状态是什么。感谢JOML贡献者和Derhass的帮助!