public float m[] = new float[16];

private float r[]; //result temp

private GLMatrix mat; //only need m[], setAA(), setTranslate(), setScale(), set(), get()

private GLVector3 vec;

public GLMatrix() {

setIdentity();

mat = new GLMatrix(false); //do not need mat,vec,r in mat

vec = new GLVector3();

r = new float[16];

}

//this ctor does not create mat,vec,r

private GLMatrix(boolean dummy) {

setIdentity();

}

public Object clone() {

GLMatrix cln = new GLMatrix();

for(int a=0;a<16;a++) cln.m[a] = m[a];

return cln;

}

public void setIdentity() {

for(int a=0;a<16;a++) {

if (a % 5 == 0)

m[a] = 1.0f;

else

m[a] = 0.0f;

}

}

public void setIdentity3x3() { //effectively reset rotation

for(int a=0;a<11;a++) {

if (a % 5 == 0)

m[a] = 1.0f;

else

m[a] = 0.0f;

}

}

public void set(GLMatrix src) {

for(int a=0;a<16;a++) m[a] = src.m[a];

}

//convert angle-axis(vector) into matrix (en.wikipedia.org/wiki/Axis_angle)

public void setAA(float angle, float x, float y, float z) {

float xx, yy, zz, xy, yz, zx, xs, ys, zs, one_c, s, c;

s = (float)Math.sin( angle * (float)Math.PI / 180.0f );

c = (float)Math.cos( angle * (float)Math.PI / 180.0f );

setIdentity();

if (x == 0.0f) {

if (y == 0.0f) {

if (z != 0.0f) {

/* rotate only around z-axis */

m[0+0*4] = c;

m[1+1*4] = c;

if (z < 0.0) {

m[0+1*4] = s;

m[1+0*4] = -s;

} else {

m[0+1*4] = -s;

m[1+0*4] = s;

}

return;

}

} else if (z == 0.0f) {

/* rotate only around y-axis */

m[0+0*4] = c;

m[2+2*4] = c;

if (y < 0.0) {

m[0+2*4] = -s;

m[2+0*4] = s;

} else {

m[0+2*4] = s;

m[2+0*4] = -s;

}

return;

}

} else if (y == 0.0f) {

if (z == 0.0f) {

/* rotate only around x-axis */

m[1+1*4] = c;

m[2+2*4] = c;

if (x < 0.0) {

m[1+2*4] = s;

m[2+1*4] = -s;

} else {

m[1+2*4] = -s;

m[2+1*4] = s;

}

return;

}

}

float mag;

//complex rotation

mag = (float)Math.sqrt(x * x + y * y + z * z);

if (mag <= 1.0e-4f) return; //rotation too small

x /= mag;

y /= mag;

z /= mag;

xx = x * x;

yy = y * y;

zz = z * z;

xy = x * y;

yz = y * z;

zx = z * x;

xs = x * s;

ys = y * s;

zs = z * s;

one_c = 1.0f - c;

m[0+0*4] = (one_c * xx) + c;

m[0+1*4] = (one_c * xy) - zs;

m[0+2*4] = (one_c * zx) + ys;

m[1+0*4] = (one_c * xy) + zs;

m[1+1*4] = (one_c * yy) + c;

m[1+2*4] = (one_c * yz) - xs;

m[2+0*4] = (one_c * zx) - ys;

m[2+1*4] = (one_c * yz) + xs;

m[2+2*4] = (one_c * zz) + c;

}

public void setAATranslate(float angle, float x, float y, float z, float tx, float ty, float tz) {

setAA(angle,x,y,z); //sets identity

addTranslate(tx, ty, tz);

}

public void setTranslate(float x, float y, float z) {

setIdentity();

m[0+3*4] = x;

m[1+3*4] = y;

m[2+3*4] = z;

}

public void setScale(float x, float y, float z) {

setIdentity();

m[0+0*4] = x;

m[1+1*4] = y;

m[2+2*4] = z;

}

/** Adds rotation assuming there is currently no translation. */

public void addRotate(float angle, float ax, float ay, float az) {

mat.setAA(angle, ax, ay, az);

mult3x3(mat);

}

/** Adds rotation with current translation. */

public void addRotate2(float angle, float ax, float ay, float az) {

mat.setAA(angle, ax, ay, az);

mult4x4(mat);

}

/** Adds rotation adjusted to current rotation but assuming there is currently no translation. */

public void addRotate3(float angle, float ax, float ay, float az) {

vec.v[0] = ax;

vec.v[1] = ay;

vec.v[2] = az;

mult(vec);

mat.setAA(angle, vec.v[0], vec.v[1], vec.v[2]);

mult3x3(mat);

}

/** Adds rotation adjusted to current rotation with current translation. */

public void addRotate4(float angle, float ax, float ay, float az) {

vec.v[0] = ax;

vec.v[1] = ay;

vec.v[2] = az;

mult(vec);

mat.setAA(angle, vec.v[0], vec.v[1], vec.v[2]);

mult4x4(mat);

}

/** Adds translation assuming there is currently no rotation. */

public void addTranslate(float tx, float ty, float tz) {

m[0+3*4] += tx;

m[1+3*4] += ty;

m[2+3*4] += tz;

}

/** Adds translation assuming there is currently no rotation. */

public void addTranslate(GLMatrix src) {

addTranslate(src.m[12], src.m[13], src.m[14]);

}

/** Adds translation with current rotation. */

public void addTranslate2(float tx, float ty, float tz) {

mat.setTranslate(tx, ty, tz);

mult4x4(mat);

}

/** Adds scale using full matrix multiple. */

public void addScale(float sx, float sy, float sz) {

mat.setScale(sx, sy, sz);

mult4x4(mat);

}

/** Multiply this matrix with another */

public void mult4x4(GLMatrix src) {

//64 mult

float a0, a1, a2, a3;

for(int col=0;col<4;col++) {

a0 = m[col+0*4];

a1 = m[col+1*4];

a2 = m[col+2*4];

a3 = m[col+3*4];

r[col+0*4] = a0 * src.m[0+0*4] + a1 * src.m[1+0*4] + a2 * src.m[2+0*4] + a3 * src.m[3+0*4];

r[col+1*4] = a0 * src.m[0+1*4] + a1 * src.m[1+1*4] + a2 * src.m[2+1*4] + a3 * src.m[3+1*4];

r[col+2*4] = a0 * src.m[0+2*4] + a1 * src.m[1+2*4] + a2 * src.m[2+2*4] + a3 * src.m[3+2*4];

r[col+3*4] = a0 * src.m[0+3*4] + a1 * src.m[1+3*4] + a2 * src.m[2+3*4] + a3 * src.m[3+3*4];

}

//swap m/r

float x[];

x = m;

m = r;

r = x;

}

/** Multiply this matrix with another (rotation/scale only) */

public void mult3x3(GLMatrix src) {

//27 mult

float a0, a1, a2;

for(int i=0;i<3;i++) {

a0 = m[i+0*4];

a1 = m[i+1*4];

a2 = m[i+2*4];

r[i+0*4] = a0 * src.m[0+0*4] + a1 * src.m[1+0*4] + a2 * src.m[2+0*4];

r[i+1*4] = a0 * src.m[0+1*4] + a1 * src.m[1+1*4] + a2 * src.m[2+1*4];

r[i+2*4] = a0 * src.m[0+2*4] + a1 * src.m[1+2*4] + a2 * src.m[2+2*4];

}

for(int a=0;a<4;a++) r[a+3*4] = m[a+3*4];

//swap m/r

float x[];

x = m;

m = r;

r = x;

}

/** 3x3 matrix multiple (rotation only) */

public void mult(GLMatrix src) {

mult3x3(src);

}

/** Multiply another 3x1 matrix with this one (3x3 part only)

public void mult(GLVector3 dest) {

float nx, ny, nz;

nx = m[0+0*4] * dest.v[0] + m[1+0*4] * dest.v[1] + m[2+0*4] * dest.v[2];

ny = m[0+1*4] * dest.v[0] + m[1+1*4] * dest.v[1] + m[2+1*4] * dest.v[2];

nz = m[0+2*4] * dest.v[0] + m[1+2*4] * dest.v[1] + m[2+2*4] * dest.v[2];

dest.v[0] = nx;

dest.v[1] = ny;

dest.v[2] = nz;

}

/** Multiply another 4x1 matrix with this one (full matrix) */

public void mult(GLVector4 dest) {

float nx, ny, nz, nw;

nx = m[0+0*4] * dest.v[0] + m[1+0*4] * dest.v[1] + m[2+0*4] * dest.v[2] + m[3+0*4] * dest.v[3];

ny = m[0+1*4] * dest.v[0] + m[1+1*4] * dest.v[1] + m[2+1*4] * dest.v[2] + m[3+1*4] * dest.v[3];

nz = m[0+2*4] * dest.v[0] + m[1+2*4] * dest.v[1] + m[2+2*4] * dest.v[2] + m[3+2*4] * dest.v[3];

nw = m[0+3*4] * dest.v[0] + m[1+3*4] * dest.v[1] + m[2+3*4] * dest.v[2] + m[3+3*4] * dest.v[3];

dest.v[0] = nx;

dest.v[1] = ny;

dest.v[2] = nz;

dest.v[3] = nw;

}

public float get(int i, int j) {return m[j + i * 4];}

public void set(int i, int j, float v) {m[j + i * 4] = v;}

/** Transpose this matrix in place. */

public void transpose() {

float t;

t = get(0, 1);

set(0, 1, get(1, 0));

set(1, 0, t);

t = get(0, 2);

set(0, 2, get(2, 0));

set(2, 0, t);

t = get(1, 2);

set(1, 2, get(2, 1));

set(2, 1, t);

}

/** Return the determinant. Computed across the zeroth row. */

public float determinant() {

return (get(0, 0) * (get(1, 1) * get(2, 2) - get(2, 1) * get(1, 2)) +

get(0, 1) * (get(2, 0) * get(1, 2) - get(1, 0) * get(2, 2)) +

get(0, 2) * (get(1, 0) * get(2, 1) - get(2, 0) * get(1, 1)));

}

/** Full matrix inversion in place. If matrix is singular, returns

public boolean invert() {

float det = determinant();

if (det == 0.0f) return false;

// Form cofactor matrix

mat.set(0, 0, get(1, 1) * get(2, 2) - get(2, 1) * get(1, 2));

mat.set(0, 1, get(2, 0) * get(1, 2) - get(1, 0) * get(2, 2));

mat.set(0, 2, get(1, 0) * get(2, 1) - get(2, 0) * get(1, 1));

mat.set(1, 0, get(2, 1) * get(0, 2) - get(0, 1) * get(2, 2));

mat.set(1, 1, get(0, 0) * get(2, 2) - get(2, 0) * get(0, 2));

mat.set(1, 2, get(2, 0) * get(0, 1) - get(0, 0) * get(2, 1));

mat.set(2, 0, get(0, 1) * get(1, 2) - get(1, 1) * get(0, 2));

mat.set(2, 1, get(1, 0) * get(0, 2) - get(0, 0) * get(1, 2));

mat.set(2, 2, get(0, 0) * get(1, 1) - get(1, 0) * get(0, 1));

// Now copy back transposed

for (int i = 0; i < 3; i++)

for (int j = 0; j < 3; j++)

set(i, j, mat.get(j, i) / det);

return true;

}

public void reverseTranslate() {

m[0+3*4] *= -1.0f;

m[1+3*4] *= -1.0f;

m[2+3*4] *= -1.0f;

}

public void frustum(float left, float right, float bottom, float top, float znear, float zfar) {

float temp, temp2, temp3, temp4;

temp = 2.0f * znear;

temp2 = right - left;

temp3 = top - bottom;

temp4 = zfar - znear;

m[0] = temp / temp2;

m[1] = 0.0f;

m[2] = 0.0f;

m[3] = 0.0f;

m[4] = 0.0f;

m[5] = temp / temp3;

m[6] = 0.0f;

m[7] = 0.0f;

m[8] = (right + left) / temp2;

m[9] = (top + bottom) / temp3;

m[10] = (-zfar - znear) / temp4;

m[11] = -1.0f;

m[12] = 0.0f;

m[13] = 0.0f;

m[14] = (-temp * zfar) / temp4;

m[15] = 0.0f;

}

private float degToRad(float x) {

return (float)(x * (Math.PI/180.0f));

}

public void perspective(float fovyInDegrees, float aspectRatio, float znear, float zfar)

{

float ymax, xmax;

ymax = (float)(znear * Math.tan(degToRad(fovyInDegrees) / 2.0f));

xmax = ymax * aspectRatio;

frustum(-xmax, xmax, -ymax, ymax, znear, zfar);

}

public void ortho(float left, float right, float bottom, float top, float near, float far) {

float w = right - left, h = top - bottom, d = far - near;

m[0] = 2 / w;

m[1] = 0;

m[2] = 0;

m[3] = 0;

m[4] = 0;

m[5] = 2 / h;

m[6] = 0;

m[7] = 0;

m[8] = 0;

m[9] = 0;

m[10] = -2 / d; //why negative ???

m[11] = 0;

m[12] = -(left + right) / w;

m[13] = -(top + bottom) / h;

m[14] = -(far + near) / d;

m[15] = 1;

}

/**

public void lookAt(GLVector3 eye, GLVector3 at, GLVector3 up) {

//see https://www.opengl.org/archives/resources/faq/technical/lookat.cpp

at.v[0] -= eye.v[0];

at.v[1] -= eye.v[1];

at.v[2] -= eye.v[2];

at.normalize();

vec.cross(at, up);

vec.normalize();

up.cross(vec, at);

at.scale(-1f);

//right vector

m[0] = vec.v[0];

m[1] = vec.v[1];

m[2] = vec.v[2];

m[3] = 0;

//up vector

m[4] = up.v[0];

m[5] = up.v[1];

m[6] = up.v[2];

m[7] = 0;

//lookAt vector

m[8] = at.v[0];

m[9] = at.v[1];

m[10] = at.v[2];

m[11] = 0;

//camera translation

m[12] = eye.v[0];

m[13] = eye.v[1];

m[14] = eye.v[2];

m[15] = 1f;

}

public String toString() {

StringBuilder sb = new StringBuilder();

sb.append("[");

for(int a=0;a<16;a+=4) {

if (a > 0) sb.append(",");

sb.append(String.format("%.3f,%.3f,%.3f,%.3f", m[a + 0], m[a + 1], m[a + 2], m[a + 3]));

}

sb.append("]");

return sb.toString();

}