/* $XFree86: xc/extras/ogl-sample/main/gfx/lib/glu/libutil/project.c,v 1.2 2001/10/28 03:32:24 tsi Exp $ */
/*
** License Applicability. Except to the extent portions of this file are
** made subject to an alternative license as permitted in the SGI Free
** Software License B, Version 1.1 (the "License"), the contents of this
** file are subject only to the provisions of the License. You may not use
** this file except in compliance with the License. You may obtain a copy
** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
** 
** http://oss.sgi.com/projects/FreeB
** 
** Note that, as provided in the License, the Software is distributed on an
** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
** 
** Original Code. The Original Code is: OpenGL Sample Implementation,
** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
** Copyright in any portions created by third parties is as indicated
** elsewhere herein. All Rights Reserved.
** 
** Additional Notice Provisions: The application programming interfaces
** established by SGI in conjunction with the Original Code are The
** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
** Window System(R) (Version 1.3), released October 19, 1998. This software
** was created using the OpenGL(R) version 1.2.1 Sample Implementation
** published by SGI, but has not been independently verified as being
** compliant with the OpenGL(R) version 1.2.1 Specification.
**
*/

#include "gluos.h"
#include <math.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include "gluint.h"

/*
** Make m an identity matrix
*/
static void __gluMakeIdentityd(GLdouble m[16])
{
    m[0+4*0] = 1; m[0+4*1] = 0; m[0+4*2] = 0; m[0+4*3] = 0;
    m[1+4*0] = 0; m[1+4*1] = 1; m[1+4*2] = 0; m[1+4*3] = 0;
    m[2+4*0] = 0; m[2+4*1] = 0; m[2+4*2] = 1; m[2+4*3] = 0;
    m[3+4*0] = 0; m[3+4*1] = 0; m[3+4*2] = 0; m[3+4*3] = 1;
}

static void __gluMakeIdentityf(GLfloat m[16])
{
    m[0+4*0] = 1; m[0+4*1] = 0; m[0+4*2] = 0; m[0+4*3] = 0;
    m[1+4*0] = 0; m[1+4*1] = 1; m[1+4*2] = 0; m[1+4*3] = 0;
    m[2+4*0] = 0; m[2+4*1] = 0; m[2+4*2] = 1; m[2+4*3] = 0;
    m[3+4*0] = 0; m[3+4*1] = 0; m[3+4*2] = 0; m[3+4*3] = 1;
}

void GLAPIENTRY
gluOrtho2D(GLdouble left, GLdouble right, GLdouble bottom, GLdouble top)
{
    glOrtho(left, right, bottom, top, -1, 1);
}

#define __glPi 3.14159265358979323846

void GLAPIENTRY
gluPerspective(GLdouble fovy, GLdouble aspect, GLdouble zNear, GLdouble zFar)
{
    GLdouble m[4][4];
    double sine, cotangent, deltaZ;
    double radians = fovy / 2 * __glPi / 180;

    deltaZ = zFar - zNear;
    sine = sin(radians);
    if ((deltaZ == 0) || (sine == 0) || (aspect == 0)) {
	return;
    }
    cotangent = COS(radians) / sine;

    __gluMakeIdentityd(&m[0][0]);
    m[0][0] = cotangent / aspect;
    m[1][1] = cotangent;
    m[2][2] = -(zFar + zNear) / deltaZ;
    m[2][3] = -1;
    m[3][2] = -2 * zNear * zFar / deltaZ;
    m[3][3] = 0;
    glMultMatrixd(&m[0][0]);
}

static void normalize(float v[3])
{
    float r;

    r = sqrt( v[0]*v[0] + v[1]*v[1] + v[2]*v[2] );
    if (r == 0.0) return;

    v[0] /= r;
    v[1] /= r;
    v[2] /= r;
}

static void cross(float v1[3], float v2[3], float result[3])
{
    result[0] = v1[1]*v2[2] - v1[2]*v2[1];
    result[1] = v1[2]*v2[0] - v1[0]*v2[2];
    result[2] = v1[0]*v2[1] - v1[1]*v2[0];
}

void GLAPIENTRY
gluLookAt(GLdouble eyex, GLdouble eyey, GLdouble eyez, GLdouble centerx,
	  GLdouble centery, GLdouble centerz, GLdouble upx, GLdouble upy,
	  GLdouble upz)
{
    float forward[3], side[3], up[3];
    GLfloat m[4][4];

    forward[0] = centerx - eyex;
    forward[1] = centery - eyey;
    forward[2] = centerz - eyez;

    up[0] = upx;
    up[1] = upy;
    up[2] = upz;

    normalize(forward);

    /* Side = forward x up */
    cross(forward, up, side);
    normalize(side);

    /* Recompute up as: up = side x forward */
    cross(side, forward, up);

    __gluMakeIdentityf(&m[0][0]);
    m[0][0] = side[0];
    m[1][0] = side[1];
    m[2][0] = side[2];

    m[0][1] = up[0];
    m[1][1] = up[1];
    m[2][1] = up[2];

    m[0][2] = -forward[0];
    m[1][2] = -forward[1];
    m[2][2] = -forward[2];

    glMultMatrixf(&m[0][0]);
    glTranslated(-eyex, -eyey, -eyez);
}

static void __gluMultMatrixVecd(const GLdouble matrix[16], const GLdouble in[4],
		      GLdouble out[4])
{
    int i;

    for (i=0; i<4; i++) {
	out[i] = 
	    in[0] * matrix[0*4+i] +
	    in[1] * matrix[1*4+i] +
	    in[2] * matrix[2*4+i] +
	    in[3] * matrix[3*4+i];
    }
}

/*
** inverse = invert(src)
*/
static int __gluInvertMatrixd(const GLdouble src[16], GLdouble inverse[16])
{
    int i, j, k, swap;
    double t;
    GLdouble temp[4][4];

    for (i=0; i<4; i++) {
	for (j=0; j<4; j++) {
	    temp[i][j] = src[i*4+j];
	}
    }
    __gluMakeIdentityd(inverse);

    for (i = 0; i < 4; i++) {
	/*
	** Look for largest element in column
	*/
	swap = i;
	for (j = i + 1; j < 4; j++) {
	    if (fabs(temp[j][i]) > fabs(temp[i][i])) {
		swap = j;
	    }
	}

	if (swap != i) {
	    /*
	    ** Swap rows.
	    */
	    for (k = 0; k < 4; k++) {
		t = temp[i][k];
		temp[i][k] = temp[swap][k];
		temp[swap][k] = t;

		t = inverse[i*4+k];
		inverse[i*4+k] = inverse[swap*4+k];
		inverse[swap*4+k] = t;
	    }
	}

	if (temp[i][i] == 0) {
	    /*
	    ** No non-zero pivot.  The matrix is singular, which shouldn't
	    ** happen.  This means the user gave us a bad matrix.
	    */
	    return GL_FALSE;
	}

	t = temp[i][i];
	for (k = 0; k < 4; k++) {
	    temp[i][k] /= t;
	    inverse[i*4+k] /= t;
	}
	for (j = 0; j < 4; j++) {
	    if (j != i) {
		t = temp[j][i];
		for (k = 0; k < 4; k++) {
		    temp[j][k] -= temp[i][k]*t;
		    inverse[j*4+k] -= inverse[i*4+k]*t;
		}
	    }
	}
    }
    return GL_TRUE;
}

static void __gluMultMatricesd(const GLdouble a[16], const GLdouble b[16],
				GLdouble r[16])
{
    int i, j;

    for (i = 0; i < 4; i++) {
	for (j = 0; j < 4; j++) {
	    r[i*4+j] = 
		a[i*4+0]*b[0*4+j] +
		a[i*4+1]*b[1*4+j] +
		a[i*4+2]*b[2*4+j] +
		a[i*4+3]*b[3*4+j];
	}
    }
}

GLint GLAPIENTRY
gluProject(GLdouble objx, GLdouble objy, GLdouble objz, 
	      const GLdouble modelMatrix[16], 
	      const GLdouble projMatrix[16],
              const GLint viewport[4],
	      GLdouble *winx, GLdouble *winy, GLdouble *winz)
{
    double in[4];
    double out[4];

    in[0]=objx;
    in[1]=objy;
    in[2]=objz;
    in[3]=1.0;
    __gluMultMatrixVecd(modelMatrix, in, out);
    __gluMultMatrixVecd(projMatrix, out, in);
    if (in[3] == 0.0) return(GL_FALSE);
    in[0] /= in[3];
    in[1] /= in[3];
    in[2] /= in[3];
    /* Map x, y and z to range 0-1 */
    in[0] = in[0] * 0.5 + 0.5;
    in[1] = in[1] * 0.5 + 0.5;
    in[2] = in[2] * 0.5 + 0.5;

    /* Map x,y to viewport */
    in[0] = in[0] * viewport[2] + viewport[0];
    in[1] = in[1] * viewport[3] + viewport[1];

    *winx=in[0];
    *winy=in[1];
    *winz=in[2];
    return(GL_TRUE);
}

GLint GLAPIENTRY
gluUnProject(GLdouble winx, GLdouble winy, GLdouble winz,
		const GLdouble modelMatrix[16], 
		const GLdouble projMatrix[16],
                const GLint viewport[4],
	        GLdouble *objx, GLdouble *objy, GLdouble *objz)
{
    double finalMatrix[16];
    double in[4];
    double out[4];

    __gluMultMatricesd(modelMatrix, projMatrix, finalMatrix);
    if (!__gluInvertMatrixd(finalMatrix, finalMatrix)) return(GL_FALSE);

    in[0]=winx;
    in[1]=winy;
    in[2]=winz;
    in[3]=1.0;

    /* Map x and y from window coordinates */
    in[0] = (in[0] - viewport[0]) / viewport[2];
    in[1] = (in[1] - viewport[1]) / viewport[3];

    /* Map to range -1 to 1 */
    in[0] = in[0] * 2 - 1;
    in[1] = in[1] * 2 - 1;
    in[2] = in[2] * 2 - 1;

    __gluMultMatrixVecd(finalMatrix, in, out);
    if (out[3] == 0.0) return(GL_FALSE);
    out[0] /= out[3];
    out[1] /= out[3];
    out[2] /= out[3];
    *objx = out[0];
    *objy = out[1];
    *objz = out[2];
    return(GL_TRUE);
}

GLint GLAPIENTRY
gluUnProject4(GLdouble winx, GLdouble winy, GLdouble winz, GLdouble clipw,
	      const GLdouble modelMatrix[16], 
	      const GLdouble projMatrix[16],
	      const GLint viewport[4],
	      GLclampd near, GLclampd far,		    
	      GLdouble *objx, GLdouble *objy, GLdouble *objz,
	      GLdouble *objw)
{
    double finalMatrix[16];
    double in[4];
    double out[4];

    __gluMultMatricesd(modelMatrix, projMatrix, finalMatrix);
    if (!__gluInvertMatrixd(finalMatrix, finalMatrix)) return(GL_FALSE);

    in[0]=winx;
    in[1]=winy;
    in[2]=winz;
    in[3]=clipw;

    /* Map x and y from window coordinates */
    in[0] = (in[0] - viewport[0]) / viewport[2];
    in[1] = (in[1] - viewport[1]) / viewport[3];
    in[2] = (in[2] - near) / (far - near);

    /* Map to range -1 to 1 */
    in[0] = in[0] * 2 - 1;
    in[1] = in[1] * 2 - 1;
    in[2] = in[2] * 2 - 1;

    __gluMultMatrixVecd(finalMatrix, in, out);
    if (out[3] == 0.0) return(GL_FALSE);
    *objx = out[0];
    *objy = out[1];
    *objz = out[2];
    *objw = out[3];
    return(GL_TRUE);
}

void GLAPIENTRY
gluPickMatrix(GLdouble x, GLdouble y, GLdouble deltax, GLdouble deltay,
		  GLint viewport[4])
{
    if (deltax <= 0 || deltay <= 0) { 
	return;
    }

    /* Translate and scale the picked region to the entire window */
    glTranslatef((viewport[2] - 2 * (x - viewport[0])) / deltax,
	    (viewport[3] - 2 * (y - viewport[1])) / deltay, 0);
    glScalef(viewport[2] / deltax, viewport[3] / deltay, 1.0);
}
