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/* Copyright (c) 2001, Stanford University
* All rights reserved
*
* See the file LICENSE.txt for information on redistributing this software.
*/
#include <float.h>
#include "cr_bbox.h"
/**
* \mainpage Util
*
* \section UtilIntroduction Introduction
*
* Chromium consists of all the top-level files in the cr
* directory. The util module basically takes care of API dispatch,
* and OpenGL state management.
*
*/
static float _vmult(const float *m, float x, float y, float z)
{
return m[0]*x + m[4]*y + m[8]*z + m[12];
}
void
crTransformBBox( float xmin, float ymin, float zmin,
float xmax, float ymax, float zmax,
const CRmatrix *m,
float *out_xmin, float *out_ymin, float *out_zmin,
float *out_xmax, float *out_ymax, float *out_zmax )
{
float x[8], y[8], z[8], w[8];
int i,j;
/* Here is the arrangement of the bounding box
*
* 0 --- 1
* |\ .\
* | 2 --- 3
* | | . |
* | | . |
* 4.|...5 |
* \| .|
* 6 --- 7
*
* c array contains the edge connectivity list
*/
static const int c[8][3] = {
{1, 2, 4},
{0, 3, 5},
{0, 3, 6},
{1, 2, 7},
{0, 5, 6},
{1, 4, 7},
{2, 4, 7},
{3, 5, 6}
};
x[0] = _vmult(&(m->m00), xmin, ymin, zmin);
x[1] = _vmult(&(m->m00), xmax, ymin, zmin);
x[2] = _vmult(&(m->m00), xmin, ymax, zmin);
x[3] = _vmult(&(m->m00), xmax, ymax, zmin);
x[4] = _vmult(&(m->m00), xmin, ymin, zmax);
x[5] = _vmult(&(m->m00), xmax, ymin, zmax);
x[6] = _vmult(&(m->m00), xmin, ymax, zmax);
x[7] = _vmult(&(m->m00), xmax, ymax, zmax);
y[0] = _vmult(&(m->m01), xmin, ymin, zmin);
y[1] = _vmult(&(m->m01), xmax, ymin, zmin);
y[2] = _vmult(&(m->m01), xmin, ymax, zmin);
y[3] = _vmult(&(m->m01), xmax, ymax, zmin);
y[4] = _vmult(&(m->m01), xmin, ymin, zmax);
y[5] = _vmult(&(m->m01), xmax, ymin, zmax);
y[6] = _vmult(&(m->m01), xmin, ymax, zmax);
y[7] = _vmult(&(m->m01), xmax, ymax, zmax);
z[0] = _vmult(&(m->m02), xmin, ymin, zmin);
z[1] = _vmult(&(m->m02), xmax, ymin, zmin);
z[2] = _vmult(&(m->m02), xmin, ymax, zmin);
z[3] = _vmult(&(m->m02), xmax, ymax, zmin);
z[4] = _vmult(&(m->m02), xmin, ymin, zmax);
z[5] = _vmult(&(m->m02), xmax, ymin, zmax);
z[6] = _vmult(&(m->m02), xmin, ymax, zmax);
z[7] = _vmult(&(m->m02), xmax, ymax, zmax);
w[0] = _vmult(&(m->m03), xmin, ymin, zmin);
w[1] = _vmult(&(m->m03), xmax, ymin, zmin);
w[2] = _vmult(&(m->m03), xmin, ymax, zmin);
w[3] = _vmult(&(m->m03), xmax, ymax, zmin);
w[4] = _vmult(&(m->m03), xmin, ymin, zmax);
w[5] = _vmult(&(m->m03), xmax, ymin, zmax);
w[6] = _vmult(&(m->m03), xmin, ymax, zmax);
w[7] = _vmult(&(m->m03), xmax, ymax, zmax);
/* Now, the object-space bbox has been transformed into
* clip-space. */
/* Find the 2D bounding box of the 3D bounding box */
xmin = ymin = zmin = FLT_MAX;
xmax = ymax = zmax = -FLT_MAX;
for (i=0; i<8; i++)
{
float xp = x[i];
float yp = y[i];
float zp = z[i];
float wp = w[i];
/* If corner is to be clipped... */
if (zp < -wp)
{
/* Point has three edges */
for (j=0; j<3; j++)
{
/* Handle the clipping... */
int k = c[i][j];
float xk = x[k];
float yk = y[k];
float zk = z[k];
float wk = w[k];
float t;
if (zp+wp-zk-wk == 0.0)
continue; /* avoid divide by zero */
else
t = (wp + zp) / (zp+wp-zk-wk);
if (t < 0.0f || t > 1.0f)
{
continue;
}
wp = wp + (wk-wp) * t;
xp = xp + (xk-xp) * t;
yp = yp + (yk-yp) * t;
zp = -wp;
xp /= wp;
yp /= wp;
zp /= wp;
if (xp < xmin) xmin = xp;
if (xp > xmax) xmax = xp;
if (yp < ymin) ymin = yp;
if (yp > ymax) ymax = yp;
if (zp < zmin) zmin = zp;
if (zp > zmax) zmax = zp;
}
}
else
{
/* corner was not clipped.. */
xp /= wp;
yp /= wp;
zp /= wp;
if (xp < xmin) xmin = xp;
if (xp > xmax) xmax = xp;
if (yp < ymin) ymin = yp;
if (yp > ymax) ymax = yp;
if (zp < zmin) zmin = zp;
if (zp > zmax) zmax = zp;
}
}
/* Copy for export */
if (out_xmin) *out_xmin = xmin;
if (out_ymin) *out_ymin = ymin;
if (out_zmin) *out_zmin = zmin;
if (out_xmax) *out_xmax = xmax;
if (out_ymax) *out_ymax = ymax;
if (out_zmax) *out_zmax = zmax;
}
/**
* Given the coordinates of the two opposite corners of a bounding box
* in object space (x1,y1,z1) and (x2,y2,z2), use the given modelview
* and projection matrices to transform the coordinates to NDC space.
* Find the 3D bounding bounding box of those eight coordinates and
* return the min/max in (x1,y1,x1) and (x2,y2,z2).
*/
void
crProjectBBox(const GLfloat modl[16], const GLfloat proj[16],
GLfloat *x1, GLfloat *y1, GLfloat *z1,
GLfloat *x2, GLfloat *y2, GLfloat *z2)
{
CRmatrix m;
/* compute product of modl and proj matrices */
m.m00 = proj[0] * modl[0] + proj[4] * modl[1] + proj[8] * modl[2] + proj[12] * modl[3];
m.m01 = proj[1] * modl[0] + proj[5] * modl[1] + proj[9] * modl[2] + proj[13] * modl[3];
m.m02 = proj[2] * modl[0] + proj[6] * modl[1] + proj[10] * modl[2] + proj[14] * modl[3];
m.m03 = proj[3] * modl[0] + proj[7] * modl[1] + proj[11] * modl[2] + proj[15] * modl[3];
m.m10 = proj[0] * modl[4] + proj[4] * modl[5] + proj[8] * modl[6] + proj[12] * modl[7];
m.m11 = proj[1] * modl[4] + proj[5] * modl[5] + proj[9] * modl[6] + proj[13] * modl[7];
m.m12 = proj[2] * modl[4] + proj[6] * modl[5] + proj[10] * modl[6] + proj[14] * modl[7];
m.m13 = proj[3] * modl[4] + proj[7] * modl[5] + proj[11] * modl[6] + proj[15] * modl[7];
m.m20 = proj[0] * modl[8] + proj[4] * modl[9] + proj[8] * modl[10] + proj[12] * modl[11];
m.m21 = proj[1] * modl[8] + proj[5] * modl[9] + proj[9] * modl[10] + proj[13] * modl[11];
m.m22 = proj[2] * modl[8] + proj[6] * modl[9] + proj[10] * modl[10] + proj[14] * modl[11];
m.m23 = proj[3] * modl[8] + proj[7] * modl[9] + proj[11] * modl[10] + proj[15] * modl[11];
m.m30 = proj[0] * modl[12] + proj[4] * modl[13] + proj[8] * modl[14] + proj[12] * modl[15];
m.m31 = proj[1] * modl[12] + proj[5] * modl[13] + proj[9] * modl[14] + proj[13] * modl[15];
m.m32 = proj[2] * modl[12] + proj[6] * modl[13] + proj[10] * modl[14] + proj[14] * modl[15];
m.m33 = proj[3] * modl[12] + proj[7] * modl[13] + proj[11] * modl[14] + proj[15] * modl[15];
crTransformBBox( *x1, *y1, *z1,
*x2, *y2, *z2,
&m,
x1, y1, z1,
x2, y2, z2 );
}
#define MIN(a, b) ((a) < (b) ? (a) : (b))
#define MAX(a, b) ((a) > (b) ? (a) : (b))
/**
* Compute union of a and b and put in result.
*/
void
crRectiUnion(CRrecti *result, const CRrecti *a, const CRrecti *b)
{
result->x1 = MIN(a->x1, b->x1);
result->x2 = MAX(a->x2, b->x2);
result->y1 = MIN(a->y1, b->y1);
result->y2 = MAX(a->y2, b->y2);
}
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