323 lines
8.8 KiB
C++
323 lines
8.8 KiB
C++
// fragment.cxx -- routines to handle "atomic" display objects
|
|
//
|
|
// Written by Curtis Olson, started August 1998.
|
|
//
|
|
// Copyright (C) 1998 Curtis L. Olson - curt@me.umn.edu
|
|
//
|
|
// This program is free software; you can redistribute it and/or
|
|
// modify it under the terms of the GNU General Public License as
|
|
// published by the Free Software Foundation; either version 2 of the
|
|
// License, or (at your option) any later version.
|
|
//
|
|
// This program is distributed in the hope that it will be useful, but
|
|
// WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
// General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU General Public License
|
|
// along with this program; if not, write to the Free Software
|
|
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
|
|
//
|
|
// $Id$
|
|
|
|
|
|
#include <Include/fg_constants.h>
|
|
#include <Math/mat3.h>
|
|
#include <Math/point3d.hxx>
|
|
#include <Scenery/tileentry.hxx>
|
|
|
|
#include "fragment.hxx"
|
|
|
|
|
|
template <class T>
|
|
inline const int FG_SIGN(const T& x) {
|
|
return x < T(0) ? -1 : 1;
|
|
}
|
|
|
|
template <class T>
|
|
inline const T& FG_MIN(const T& a, const T& b) {
|
|
return b < a ? b : a;
|
|
}
|
|
|
|
template <class T>
|
|
inline const T& FG_MAX(const T& a, const T& b) {
|
|
return a < b ? b : a;
|
|
}
|
|
|
|
// return the minimum of the three values
|
|
template <class T>
|
|
inline const T& fg_min3( const T& a, const T& b, const T& c)
|
|
{
|
|
return (a > b ? FG_MIN (b, c) : FG_MIN (a, c));
|
|
}
|
|
|
|
|
|
// return the maximum of the three values
|
|
template <class T>
|
|
inline const T& fg_max3 (const T& a, const T& b, const T& c)
|
|
{
|
|
return (a < b ? FG_MAX (b, c) : FG_MAX (a, c));
|
|
}
|
|
|
|
// Add a face to the face list
|
|
// Copy constructor
|
|
fgFRAGMENT::fgFRAGMENT ( const fgFRAGMENT & rhs ) :
|
|
center ( rhs.center ),
|
|
bounding_radius( rhs.bounding_radius ),
|
|
material_ptr ( rhs.material_ptr ),
|
|
tile_ptr ( rhs.tile_ptr ),
|
|
display_list ( rhs.display_list ),
|
|
faces ( rhs.faces )
|
|
{
|
|
}
|
|
|
|
fgFRAGMENT & fgFRAGMENT::operator = ( const fgFRAGMENT & rhs )
|
|
{
|
|
if(!(this == &rhs )) {
|
|
center = rhs.center;
|
|
bounding_radius = rhs.bounding_radius;
|
|
material_ptr = rhs.material_ptr;
|
|
tile_ptr = rhs.tile_ptr;
|
|
// display_list = rhs.display_list;
|
|
faces = rhs.faces;
|
|
}
|
|
return *this;
|
|
}
|
|
|
|
|
|
// test if line intesects with this fragment. p0 and p1 are the two
|
|
// line end points of the line. If side_flag is true, check to see
|
|
// that end points are on opposite sides of face. Returns 1 if it
|
|
// intersection found, 0 otherwise. If it intesects, result is the
|
|
// point of intersection
|
|
|
|
int fgFRAGMENT::intersect( const Point3D& end0,
|
|
const Point3D& end1,
|
|
int side_flag,
|
|
Point3D& result) const
|
|
{
|
|
FGTileEntry *t;
|
|
MAT3vec v1, v2, n, center;
|
|
double p1[3], p2[3], p3[3];
|
|
double x, y, z; // temporary holding spot for result
|
|
double a, b, c, d;
|
|
double x0, y0, z0, x1, y1, z1, a1, b1, c1;
|
|
double t1, t2, t3;
|
|
double xmin, xmax, ymin, ymax, zmin, zmax;
|
|
double dx, dy, dz, min_dim, x2, y2, x3, y3, rx, ry;
|
|
int side1, side2;
|
|
|
|
// find the associated tile
|
|
t = tile_ptr;
|
|
|
|
// printf("Intersecting\n");
|
|
|
|
// traverse the face list for this fragment
|
|
const_iterator last = faces.end();
|
|
for ( const_iterator current = faces.begin(); current != last; ++current )
|
|
{
|
|
// printf(".");
|
|
|
|
// get face vertex coordinates
|
|
center[0] = t->center.x();
|
|
center[1] = t->center.y();
|
|
center[2] = t->center.z();
|
|
|
|
MAT3_ADD_VEC(p1, t->nodes[(*current).n1], center);
|
|
MAT3_ADD_VEC(p2, t->nodes[(*current).n2], center);
|
|
MAT3_ADD_VEC(p3, t->nodes[(*current).n3], center);
|
|
|
|
// printf("point 1 = %.2f %.2f %.2f\n", p1[0], p1[1], p1[2]);
|
|
// printf("point 2 = %.2f %.2f %.2f\n", p2[0], p2[1], p2[2]);
|
|
// printf("point 3 = %.2f %.2f %.2f\n", p3[0], p3[1], p3[2]);
|
|
|
|
// calculate two edge vectors, and the face normal
|
|
MAT3_SUB_VEC(v1, p2, p1);
|
|
MAT3_SUB_VEC(v2, p3, p1);
|
|
MAT3cross_product(n, v1, v2);
|
|
|
|
// calculate the plane coefficients for the plane defined by
|
|
// this face. If n is the normal vector, n = (a, b, c) and p1
|
|
// is a point on the plane, p1 = (x0, y0, z0), then the
|
|
// equation of the line is a(x-x0) + b(y-y0) + c(z-z0) = 0
|
|
a = n[0];
|
|
b = n[1];
|
|
c = n[2];
|
|
d = a * p1[0] + b * p1[1] + c * p1[2];
|
|
// printf("a, b, c, d = %.2f %.2f %.2f %.2f\n", a, b, c, d);
|
|
|
|
// printf("p1(d) = %.2f\n", a * p1[0] + b * p1[1] + c * p1[2]);
|
|
// printf("p2(d) = %.2f\n", a * p2[0] + b * p2[1] + c * p2[2]);
|
|
// printf("p3(d) = %.2f\n", a * p3[0] + b * p3[1] + c * p3[2]);
|
|
|
|
// calculate the line coefficients for the specified line
|
|
x0 = end0.x(); x1 = end1.x();
|
|
y0 = end0.y(); y1 = end1.y();
|
|
z0 = end0.z(); z1 = end1.z();
|
|
|
|
if ( fabs(x1 - x0) > FG_EPSILON ) {
|
|
a1 = 1.0 / (x1 - x0);
|
|
} else {
|
|
// we got a big divide by zero problem here
|
|
a1 = 0.0;
|
|
}
|
|
b1 = y1 - y0;
|
|
c1 = z1 - z0;
|
|
|
|
// intersect the specified line with this plane
|
|
t1 = b * b1 * a1;
|
|
t2 = c * c1 * a1;
|
|
|
|
// printf("a = %.2f t1 = %.2f t2 = %.2f\n", a, t1, t2);
|
|
|
|
if ( fabs(a + t1 + t2) > FG_EPSILON ) {
|
|
x = (t1*x0 - b*y0 + t2*x0 - c*z0 + d) / (a + t1 + t2);
|
|
t3 = a1 * (x - x0);
|
|
y = b1 * t3 + y0;
|
|
z = c1 * t3 + z0;
|
|
// printf("result(d) = %.2f\n", a * x + b * y + c * z);
|
|
} else {
|
|
// no intersection point
|
|
continue;
|
|
}
|
|
|
|
if ( side_flag ) {
|
|
// check to see if end0 and end1 are on opposite sides of
|
|
// plane
|
|
if ( (x - x0) > FG_EPSILON ) {
|
|
t1 = x;
|
|
t2 = x0;
|
|
t3 = x1;
|
|
} else if ( (y - y0) > FG_EPSILON ) {
|
|
t1 = y;
|
|
t2 = y0;
|
|
t3 = y1;
|
|
} else if ( (z - z0) > FG_EPSILON ) {
|
|
t1 = z;
|
|
t2 = z0;
|
|
t3 = z1;
|
|
} else {
|
|
// everything is too close together to tell the difference
|
|
// so the current intersection point should work as good
|
|
// as any
|
|
result = Point3D(x, y, z);
|
|
return(1);
|
|
}
|
|
side1 = FG_SIGN (t1 - t2);
|
|
side2 = FG_SIGN (t1 - t3);
|
|
if ( side1 == side2 ) {
|
|
// same side, punt
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// check to see if intersection point is in the bounding
|
|
// cube of the face
|
|
#ifdef XTRA_DEBUG_STUFF
|
|
xmin = fg_min3 (p1[0], p2[0], p3[0]);
|
|
xmax = fg_max3 (p1[0], p2[0], p3[0]);
|
|
ymin = fg_min3 (p1[1], p2[1], p3[1]);
|
|
ymax = fg_max3 (p1[1], p2[1], p3[1]);
|
|
zmin = fg_min3 (p1[2], p2[2], p3[2]);
|
|
zmax = fg_max3 (p1[2], p2[2], p3[2]);
|
|
printf("bounding cube = %.2f,%.2f,%.2f %.2f,%.2f,%.2f\n",
|
|
xmin, ymin, zmin, xmax, ymax, zmax);
|
|
#endif
|
|
// punt if outside bouding cube
|
|
if ( x < (xmin = fg_min3 (p1[0], p2[0], p3[0])) ) {
|
|
continue;
|
|
} else if ( x > (xmax = fg_max3 (p1[0], p2[0], p3[0])) ) {
|
|
continue;
|
|
} else if ( y < (ymin = fg_min3 (p1[1], p2[1], p3[1])) ) {
|
|
continue;
|
|
} else if ( y > (ymax = fg_max3 (p1[1], p2[1], p3[1])) ) {
|
|
continue;
|
|
} else if ( z < (zmin = fg_min3 (p1[2], p2[2], p3[2])) ) {
|
|
continue;
|
|
} else if ( z > (zmax = fg_max3 (p1[2], p2[2], p3[2])) ) {
|
|
continue;
|
|
}
|
|
|
|
// (finally) check to see if the intersection point is
|
|
// actually inside this face
|
|
|
|
//first, drop the smallest dimension so we only have to work
|
|
//in 2d.
|
|
dx = xmax - xmin;
|
|
dy = ymax - ymin;
|
|
dz = zmax - zmin;
|
|
min_dim = fg_min3 (dx, dy, dz);
|
|
if ( fabs(min_dim - dx) <= FG_EPSILON ) {
|
|
// x is the smallest dimension
|
|
x1 = p1[1];
|
|
y1 = p1[2];
|
|
x2 = p2[1];
|
|
y2 = p2[2];
|
|
x3 = p3[1];
|
|
y3 = p3[2];
|
|
rx = y;
|
|
ry = z;
|
|
} else if ( fabs(min_dim - dy) <= FG_EPSILON ) {
|
|
// y is the smallest dimension
|
|
x1 = p1[0];
|
|
y1 = p1[2];
|
|
x2 = p2[0];
|
|
y2 = p2[2];
|
|
x3 = p3[0];
|
|
y3 = p3[2];
|
|
rx = x;
|
|
ry = z;
|
|
} else if ( fabs(min_dim - dz) <= FG_EPSILON ) {
|
|
// z is the smallest dimension
|
|
x1 = p1[0];
|
|
y1 = p1[1];
|
|
x2 = p2[0];
|
|
y2 = p2[1];
|
|
x3 = p3[0];
|
|
y3 = p3[1];
|
|
rx = x;
|
|
ry = y;
|
|
} else {
|
|
// all dimensions are really small so lets call it close
|
|
// enough and return a successful match
|
|
result = Point3D(x, y, z);
|
|
return(1);
|
|
}
|
|
|
|
// check if intersection point is on the same side of p1 <-> p2 as p3
|
|
t1 = (y1 - y2) / (x1 - x2);
|
|
side1 = FG_SIGN (t1 * ((x3) - x2) + y2 - (y3));
|
|
side2 = FG_SIGN (t1 * ((rx) - x2) + y2 - (ry));
|
|
if ( side1 != side2 ) {
|
|
// printf("failed side 1 check\n");
|
|
continue;
|
|
}
|
|
|
|
// check if intersection point is on correct side of p2 <-> p3 as p1
|
|
t1 = (y2 - y3) / (x2 - x3);
|
|
side1 = FG_SIGN (t1 * ((x1) - x3) + y3 - (y1));
|
|
side2 = FG_SIGN (t1 * ((rx) - x3) + y3 - (ry));
|
|
if ( side1 != side2 ) {
|
|
// printf("failed side 2 check\n");
|
|
continue;
|
|
}
|
|
|
|
// check if intersection point is on correct side of p1 <-> p3 as p2
|
|
t1 = (y1 - y3) / (x1 - x3);
|
|
side1 = FG_SIGN (t1 * ((x2) - x3) + y3 - (y2));
|
|
side2 = FG_SIGN (t1 * ((rx) - x3) + y3 - (ry));
|
|
if ( side1 != side2 ) {
|
|
// printf("failed side 3 check\n");
|
|
continue;
|
|
}
|
|
|
|
// printf( "intersection point = %.2f %.2f %.2f\n", x, y, z);
|
|
result = Point3D(x, y, z);
|
|
return(1);
|
|
}
|
|
|
|
// printf("\n");
|
|
|
|
return(0);
|
|
}
|
|
|