android/renderscript/Matrix4f.java

/*
 * Copyright (C) 2009-2012 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.renderscript;

import java.lang.Math;
import android.util.Log;


/**
 * Class for exposing the native Renderscript rs_matrix4x4 type back to the Android system.
 *
 **/
public class Matrix4f {

    /**
    * Creates a new identity 4x4 matrix
    */
    public Matrix4f() {
        mMat = new float[16];
        loadIdentity();
    }

    /**
    * Creates a new matrix and sets its values from the given
    * parameter
    *
    * @param dataArray values to set the matrix to, must be 16
    *                  floats long
    */
    public Matrix4f(float[] dataArray) {
        mMat = new float[16];
        System.arraycopy(dataArray, 0, mMat, 0, mMat.length);
    }

    /**
    * Return a reference to the internal array representing matrix
    * values. Modifying this array will also change the matrix
    *
    * @return internal array representing the matrix
    */
    public float[] getArray() {
        return mMat;
    }

    /**
    * Returns the value for a given row and column
    *
    * @param x column of the value to return
    * @param y row of the value to return
    *
    * @return value in the yth row and xth column
    */
    public float get(int x, int y) {
        return mMat[x*4 + y];
    }

    /**
    * Sets the value for a given row and column
    *
    * @param x column of the value to set
    * @param y row of the value to set
    */
    public void set(int x, int y, float v) {
        mMat[x*4 + y] = v;
    }

    /**
    * Sets the matrix values to identity
    */
    public void loadIdentity() {
        mMat[0] = 1;
        mMat[1] = 0;
        mMat[2] = 0;
        mMat[3] = 0;

        mMat[4] = 0;
        mMat[5] = 1;
        mMat[6] = 0;
        mMat[7] = 0;

        mMat[8] = 0;
        mMat[9] = 0;
        mMat[10] = 1;
        mMat[11] = 0;

        mMat[12] = 0;
        mMat[13] = 0;
        mMat[14] = 0;
        mMat[15] = 1;
    }

    /**
    * Sets the values of the matrix to those of the parameter
    *
    * @param src matrix to load the values from
    */
    public void load(Matrix4f src) {
        System.arraycopy(src.getArray(), 0, mMat, 0, mMat.length);
    }

    /**
    * Sets current values to be a rotation matrix of certain angle
    * about a given axis
    *
    * @param rot angle of rotation
    * @param x rotation axis x
    * @param y rotation axis y
    * @param z rotation axis z
    */
    public void loadRotate(float rot, float x, float y, float z) {
        float c, s;
        mMat[3] = 0;
        mMat[7] = 0;
        mMat[11]= 0;
        mMat[12]= 0;
        mMat[13]= 0;
        mMat[14]= 0;
        mMat[15]= 1;
        rot *= (float)(java.lang.Math.PI / 180.0f);
        c = (float)java.lang.Math.cos(rot);
        s = (float)java.lang.Math.sin(rot);

        float len = (float)java.lang.Math.sqrt(x*x + y*y + z*z);
        if (!(len != 1)) {
            float recipLen = 1.f / len;
            x *= recipLen;
            y *= recipLen;
            z *= recipLen;
        }
        float nc = 1.0f - c;
        float xy = x * y;
        float yz = y * z;
        float zx = z * x;
        float xs = x * s;
        float ys = y * s;
        float zs = z * s;
        mMat[ 0] = x*x*nc +  c;
        mMat[ 4] =  xy*nc - zs;
        mMat[ 8] =  zx*nc + ys;
        mMat[ 1] =  xy*nc + zs;
        mMat[ 5] = y*y*nc +  c;
        mMat[ 9] =  yz*nc - xs;
        mMat[ 2] =  zx*nc - ys;
        mMat[ 6] =  yz*nc + xs;
        mMat[10] = z*z*nc +  c;
    }

    /**
    * Sets current values to be a scale matrix of given dimensions
    *
    * @param x scale component x
    * @param y scale component y
    * @param z scale component z
    */
    public void loadScale(float x, float y, float z) {
        loadIdentity();
        mMat[0] = x;
        mMat[5] = y;
        mMat[10] = z;
    }

    /**
    * Sets current values to be a translation matrix of given
    * dimensions
    *
    * @param x translation component x
    * @param y translation component y
    * @param z translation component z
    */
    public void loadTranslate(float x, float y, float z) {
        loadIdentity();
        mMat[12] = x;
        mMat[13] = y;
        mMat[14] = z;
    }

    /**
    * Sets current values to be the result of multiplying two given
    * matrices
    *
    * @param lhs left hand side matrix
    * @param rhs right hand side matrix
    */
    public void loadMultiply(Matrix4f lhs, Matrix4f rhs) {
        for (int i=0 ; i<4 ; i++) {
            float ri0 = 0;
            float ri1 = 0;
            float ri2 = 0;
            float ri3 = 0;
            for (int j=0 ; j<4 ; j++) {
                float rhs_ij = rhs.get(i,j);
                ri0 += lhs.get(j,0) * rhs_ij;
                ri1 += lhs.get(j,1) * rhs_ij;
                ri2 += lhs.get(j,2) * rhs_ij;
                ri3 += lhs.get(j,3) * rhs_ij;
            }
            set(i,0, ri0);
            set(i,1, ri1);
            set(i,2, ri2);
            set(i,3, ri3);
        }
    }

    /**
    * Set current values to be an orthographic projection matrix
    *
    * @param l location of the left vertical clipping plane
    * @param r location of the right vertical clipping plane
    * @param b location of the bottom horizontal clipping plane
    * @param t location of the top horizontal clipping plane
    * @param n location of the near clipping plane
    * @param f location of the far clipping plane
    */
    public void loadOrtho(float l, float r, float b, float t, float n, float f) {
        loadIdentity();
        mMat[0] = 2 / (r - l);
        mMat[5] = 2 / (t - b);
        mMat[10]= -2 / (f - n);
        mMat[12]= -(r + l) / (r - l);
        mMat[13]= -(t + b) / (t - b);
        mMat[14]= -(f + n) / (f - n);
    }

    /**
    * Set current values to be an orthographic projection matrix
    * with the right and bottom clipping planes set to the given
    * values. Left and top clipping planes are set to 0. Near and
    * far are set to -1, 1 respectively
    *
    * @param w location of the right vertical clipping plane
    * @param h location of the bottom horizontal clipping plane
    *
    */
    public void loadOrthoWindow(int w, int h) {
        loadOrtho(0,w, h,0, -1,1);
    }

    /**
    * Sets current values to be a perspective projection matrix
    *
    * @param l location of the left vertical clipping plane
    * @param r location of the right vertical clipping plane
    * @param b location of the bottom horizontal clipping plane
    * @param t location of the top horizontal clipping plane
    * @param n location of the near clipping plane, must be positive
    * @param f location of the far clipping plane, must be positive
    *
    */
    public void loadFrustum(float l, float r, float b, float t, float n, float f) {
        loadIdentity();
        mMat[0] = 2 * n / (r - l);
        mMat[5] = 2 * n / (t - b);
        mMat[8] = (r + l) / (r - l);
        mMat[9] = (t + b) / (t - b);
        mMat[10]= -(f + n) / (f - n);
        mMat[11]= -1;
        mMat[14]= -2*f*n / (f - n);
        mMat[15]= 0;
    }

    /**
    * Sets current values to be a perspective projection matrix
    *
    * @param fovy vertical field of view angle in degrees
    * @param aspect aspect ratio of the screen
    * @param near near cliping plane, must be positive
    * @param far far clipping plane, must be positive
    */
    public void loadPerspective(float fovy, float aspect, float near, float far) {
        float top = near * (float)Math.tan((float) (fovy * Math.PI / 360.0f));
        float bottom = -top;
        float left = bottom * aspect;
        float right = top * aspect;
        loadFrustum(left, right, bottom, top, near, far);
    }

    /**
    * Helper function to set the current values to a perspective
    * projection matrix with aspect ratio defined by the parameters
    * and (near, far), (bottom, top) mapping to (-1, 1) at z = 0
    *
    * @param w screen width
    * @param h screen height
    */
    public void loadProjectionNormalized(int w, int h) {
        // range -1,1 in the narrow axis at z = 0.
        Matrix4f m1 = new Matrix4f();
        Matrix4f m2 = new Matrix4f();

        if(w > h) {
            float aspect = ((float)w) / h;
            m1.loadFrustum(-aspect,aspect,  -1,1,  1,100);
        } else {
            float aspect = ((float)h) / w;
            m1.loadFrustum(-1,1, -aspect,aspect, 1,100);
        }

        m2.loadRotate(180, 0, 1, 0);
        m1.loadMultiply(m1, m2);

        m2.loadScale(-2, 2, 1);
        m1.loadMultiply(m1, m2);

        m2.loadTranslate(0, 0, 2);
        m1.loadMultiply(m1, m2);

        load(m1);
    }

    /**
    * Post-multiplies the current matrix by a given parameter
    *
    * @param rhs right hand side to multiply by
    */
    public void multiply(Matrix4f rhs) {
        Matrix4f tmp = new Matrix4f();
        tmp.loadMultiply(this, rhs);
        load(tmp);
    }
    /**
    * Modifies the current matrix by post-multiplying it with a
    * rotation matrix of certain angle about a given axis
    *
    * @param rot angle of rotation
    * @param x rotation axis x
    * @param y rotation axis y
    * @param z rotation axis z
    */
    public void rotate(float rot, float x, float y, float z) {
        Matrix4f tmp = new Matrix4f();
        tmp.loadRotate(rot, x, y, z);
        multiply(tmp);
    }

    /**
    * Modifies the current matrix by post-multiplying it with a
    * scale matrix of given dimensions
    *
    * @param x scale component x
    * @param y scale component y
    * @param z scale component z
    */
    public void scale(float x, float y, float z) {
        Matrix4f tmp = new Matrix4f();
        tmp.loadScale(x, y, z);
        multiply(tmp);
    }

    /**
    * Modifies the current matrix by post-multiplying it with a
    * translation matrix of given dimensions
    *
    * @param x translation component x
    * @param y translation component y
    * @param z translation component z
    */
    public void translate(float x, float y, float z) {
        Matrix4f tmp = new Matrix4f();
        tmp.loadTranslate(x, y, z);
        multiply(tmp);
    }
    private float computeCofactor(int i, int j) {
        int c0 = (i+1) % 4;
        int c1 = (i+2) % 4;
        int c2 = (i+3) % 4;
        int r0 = (j+1) % 4;
        int r1 = (j+2) % 4;
        int r2 = (j+3) % 4;

        float minor = (mMat[c0 + 4*r0] * (mMat[c1 + 4*r1] * mMat[c2 + 4*r2] -
                                            mMat[c1 + 4*r2] * mMat[c2 + 4*r1]))
                     - (mMat[c0 + 4*r1] * (mMat[c1 + 4*r0] * mMat[c2 + 4*r2] -
                                            mMat[c1 + 4*r2] * mMat[c2 + 4*r0]))
                     + (mMat[c0 + 4*r2] * (mMat[c1 + 4*r0] * mMat[c2 + 4*r1] -
                                            mMat[c1 + 4*r1] * mMat[c2 + 4*r0]));

        float cofactor = ((i+j) & 1) != 0 ? -minor : minor;
        return cofactor;
    }

    /**
    * Sets the current matrix to its inverse
    */
    public boolean inverse() {

        Matrix4f result = new Matrix4f();

        for (int i = 0; i < 4; ++i) {
            for (int j = 0; j < 4; ++j) {
                result.mMat[4*i + j] = computeCofactor(i, j);
            }
        }

        // Dot product of 0th column of source and 0th row of result
        float det = mMat[0]*result.mMat[0] + mMat[4]*result.mMat[1] +
                     mMat[8]*result.mMat[2] + mMat[12]*result.mMat[3];

        if (Math.abs(det) < 1e-6) {
            return false;
        }

        det = 1.0f / det;
        for (int i = 0; i < 16; ++i) {
            mMat[i] = result.mMat[i] * det;
        }

        return true;
    }

    /**
    * Sets the current matrix to its inverse transpose
    */
    public boolean inverseTranspose() {

        Matrix4f result = new Matrix4f();

        for (int i = 0; i < 4; ++i) {
            for (int j = 0; j < 4; ++j) {
                result.mMat[4*j + i] = computeCofactor(i, j);
            }
        }

        float det = mMat[0]*result.mMat[0] + mMat[4]*result.mMat[4] +
                     mMat[8]*result.mMat[8] + mMat[12]*result.mMat[12];

        if (Math.abs(det) < 1e-6) {
            return false;
        }

        det = 1.0f / det;
        for (int i = 0; i < 16; ++i) {
            mMat[i] = result.mMat[i] * det;
        }

        return true;
    }

    /**
    * Sets the current matrix to its transpose
    */
    public void transpose() {
        for(int i = 0; i < 3; ++i) {
            for(int j = i + 1; j < 4; ++j) {
                float temp = mMat[i*4 + j];
                mMat[i*4 + j] = mMat[j*4 + i];
                mMat[j*4 + i] = temp;
            }
        }
    }

    final float[] mMat;
}