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/*
THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
SOFTWARE CORPORATION ("PARALLAX"). PARALLAX, IN DISTRIBUTING THE CODE TO
END-USERS, AND SUBJECT TO ALL OF THE TERMS AND CONDITIONS HEREIN, GRANTS A
ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS
IN USING, DISPLAYING, AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS
SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE
FREE PURPOSES. IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE
CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES. THE END-USER UNDERSTANDS
AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.
COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION. ALL RIGHTS RESERVED.
*/
/*
*
* Routines for point definition, rotation, etc.
*
*/
#include "3d.h"
#include "globvars.h"
//code a point. fills in the p3_codes field of the point, and returns the codes
ubyte g3_code_point(g3s_point *p)
{
ubyte cc=0;
if (p->p3_x > p->p3_z)
cc |= CC_OFF_RIGHT;
if (p->p3_y > p->p3_z)
cc |= CC_OFF_TOP;
if (p->p3_x < -p->p3_z)
cc |= CC_OFF_LEFT;
if (p->p3_y < -p->p3_z)
cc |= CC_OFF_BOT;
if (p->p3_z < 0)
cc |= CC_BEHIND;
return p->p3_codes = cc;
}
//rotates a point. returns codes. does not check if already rotated
ubyte g3_rotate_point(g3s_point *dest,const vms_vector *src)
{
vms_vector tempv;
vm_vec_sub(&tempv,src,&View_position);
vm_vec_rotate(&dest->p3_vec,&tempv,&View_matrix);
dest->p3_flags = 0; //no projected
return g3_code_point(dest);
}
//checks for overflow & divides if ok, fillig in r
//returns true if div is ok, else false
int checkmuldiv(fix *r,fix a,fix b,fix c)
{
quadint q,qt;
q.low=q.high=0;
fixmulaccum(&q,a,b);
qt = q;
if (qt.high < 0)
fixquadnegate(&qt);
qt.high *= 2;
if (qt.low > 0x7fff)
qt.high++;
if (qt.high >= c)
return 0;
else {
*r = fixdivquadlong(q.low,q.high,c);
return 1;
}
}
//projects a point
void g3_project_point(g3s_point *p)
{
#ifndef __powerc
fix tx,ty;
if (p->p3_flags & PF_PROJECTED || p->p3_codes & CC_BEHIND)
return;
if (checkmuldiv(&tx,p->p3_x,Canv_w2,p->p3_z) && checkmuldiv(&ty,p->p3_y,Canv_h2,p->p3_z)) {
p->p3_sx = Canv_w2 + tx;
p->p3_sy = Canv_h2 - ty;
p->p3_flags |= PF_PROJECTED;
}
else
p->p3_flags |= PF_OVERFLOW;
#else
double fz;
if ((p->p3_flags & PF_PROJECTED) || (p->p3_codes & CC_BEHIND))
return;
if ( p->p3_z <= 0 ) {
p->p3_flags |= PF_OVERFLOW;
return;
}
fz = f2fl(p->p3_z);
p->p3_sx = fl2f(fCanv_w2 + (f2fl(p->p3_x)*fCanv_w2 / fz));
p->p3_sy = fl2f(fCanv_h2 - (f2fl(p->p3_y)*fCanv_h2 / fz));
p->p3_flags |= PF_PROJECTED;
#endif
}
//from a 2d point, compute the vector through that point
void g3_point_2_vec(vms_vector *v,short sx,short sy)
{
vms_vector tempv;
vms_matrix tempm;
tempv.x = fixmuldiv(fixdiv((sx<<16) - Canv_w2,Canv_w2),Matrix_scale.z,Matrix_scale.x);
tempv.y = -fixmuldiv(fixdiv((sy<<16) - Canv_h2,Canv_h2),Matrix_scale.z,Matrix_scale.y);
tempv.z = f1_0;
vm_vec_normalize(&tempv);
vm_copy_transpose_matrix(&tempm,&Unscaled_matrix);
vm_vec_rotate(v,&tempv,&tempm);
}
//delta rotation functions
vms_vector *g3_rotate_delta_x(vms_vector *dest,fix dx)
{
dest->x = fixmul(View_matrix.rvec.x,dx);
dest->y = fixmul(View_matrix.uvec.x,dx);
dest->z = fixmul(View_matrix.fvec.x,dx);
return dest;
}
vms_vector *g3_rotate_delta_y(vms_vector *dest,fix dy)
{
dest->x = fixmul(View_matrix.rvec.y,dy);
dest->y = fixmul(View_matrix.uvec.y,dy);
dest->z = fixmul(View_matrix.fvec.y,dy);
return dest;
}
vms_vector *g3_rotate_delta_z(vms_vector *dest,fix dz)
{
dest->x = fixmul(View_matrix.rvec.z,dz);
dest->y = fixmul(View_matrix.uvec.z,dz);
dest->z = fixmul(View_matrix.fvec.z,dz);
return dest;
}
vms_vector *g3_rotate_delta_vec(vms_vector *dest,vms_vector *src)
{
return vm_vec_rotate(dest,src,&View_matrix);
}
ubyte g3_add_delta_vec(g3s_point *dest,g3s_point *src,vms_vector *deltav)
{
vm_vec_add(&dest->p3_vec,&src->p3_vec,deltav);
dest->p3_flags = 0; //not projected
return g3_code_point(dest);
}
//calculate the depth of a point - returns the z coord of the rotated point
fix g3_calc_point_depth(vms_vector *pnt)
{
quadint q;
q.low=q.high=0;
fixmulaccum(&q,(pnt->x - View_position.x),View_matrix.fvec.x);
fixmulaccum(&q,(pnt->y - View_position.y),View_matrix.fvec.y);
fixmulaccum(&q,(pnt->z - View_position.z),View_matrix.fvec.z);
return fixquadadjust(&q);
}
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