2 THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
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5 ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS
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7 SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE
8 FREE PURPOSES. IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE
9 CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES. THE END-USER UNDERSTANDS
10 AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.
11 COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION. ALL RIGHTS RESERVED.
15 * Routines for point definition, rotation, etc.
27 //code a point. fills in the p3_codes field of the point, and returns the codes
28 ubyte g3_code_point(g3s_point *p)
32 if (p->p3_x > p->p3_z)
35 if (p->p3_y > p->p3_z)
38 if (p->p3_x < -p->p3_z)
41 if (p->p3_y < -p->p3_z)
47 return p->p3_codes = cc;
51 //rotates a point. returns codes. does not check if already rotated
52 ubyte g3_rotate_point(g3s_point *dest,const vms_vector *src)
56 vm_vec_sub(&tempv,src,&View_position);
58 vm_vec_rotate(&dest->p3_vec,&tempv,&View_matrix);
60 dest->p3_flags = 0; //no projected
62 return g3_code_point(dest);
66 //checks for overflow & divides if ok, fillig in r
67 //returns true if div is ok, else false
68 int checkmuldiv(fix *r,fix a,fix b,fix c)
86 *r = fixdivquadlong(q.low,q.high,c);
92 void g3_project_point(g3s_point *p)
97 if (p->p3_flags & PF_PROJECTED || p->p3_codes & CC_BEHIND)
100 if (checkmuldiv(&tx,p->p3_x,Canv_w2,p->p3_z) && checkmuldiv(&ty,p->p3_y,Canv_h2,p->p3_z)) {
101 p->p3_sx = Canv_w2 + tx;
102 p->p3_sy = Canv_h2 - ty;
103 p->p3_flags |= PF_PROJECTED;
106 p->p3_flags |= PF_OVERFLOW;
110 if ((p->p3_flags & PF_PROJECTED) || (p->p3_codes & CC_BEHIND))
113 if ( p->p3_z <= 0 ) {
114 p->p3_flags |= PF_OVERFLOW;
119 p->p3_sx = fl2f(fCanv_w2 + (f2fl(p->p3_x)*fCanv_w2 / fz));
120 p->p3_sy = fl2f(fCanv_h2 - (f2fl(p->p3_y)*fCanv_h2 / fz));
122 p->p3_flags |= PF_PROJECTED;
126 //from a 2d point, compute the vector through that point
127 void g3_point_2_vec(vms_vector *v,short sx,short sy)
132 tempv.x = fixmuldiv(fixdiv((sx<<16) - Canv_w2,Canv_w2),Matrix_scale.z,Matrix_scale.x);
133 tempv.y = -fixmuldiv(fixdiv((sy<<16) - Canv_h2,Canv_h2),Matrix_scale.z,Matrix_scale.y);
136 vm_vec_normalize(&tempv);
138 vm_copy_transpose_matrix(&tempm,&Unscaled_matrix);
140 vm_vec_rotate(v,&tempv,&tempm);
144 //delta rotation functions
145 vms_vector *g3_rotate_delta_x(vms_vector *dest,fix dx)
147 dest->x = fixmul(View_matrix.rvec.x,dx);
148 dest->y = fixmul(View_matrix.uvec.x,dx);
149 dest->z = fixmul(View_matrix.fvec.x,dx);
154 vms_vector *g3_rotate_delta_y(vms_vector *dest,fix dy)
156 dest->x = fixmul(View_matrix.rvec.y,dy);
157 dest->y = fixmul(View_matrix.uvec.y,dy);
158 dest->z = fixmul(View_matrix.fvec.y,dy);
163 vms_vector *g3_rotate_delta_z(vms_vector *dest,fix dz)
165 dest->x = fixmul(View_matrix.rvec.z,dz);
166 dest->y = fixmul(View_matrix.uvec.z,dz);
167 dest->z = fixmul(View_matrix.fvec.z,dz);
173 vms_vector *g3_rotate_delta_vec(vms_vector *dest,vms_vector *src)
175 return vm_vec_rotate(dest,src,&View_matrix);
178 ubyte g3_add_delta_vec(g3s_point *dest,g3s_point *src,vms_vector *deltav)
180 vm_vec_add(&dest->p3_vec,&src->p3_vec,deltav);
182 dest->p3_flags = 0; //not projected
184 return g3_code_point(dest);
187 //calculate the depth of a point - returns the z coord of the rotated point
188 fix g3_calc_point_depth(vms_vector *pnt)
193 fixmulaccum(&q,(pnt->x - View_position.x),View_matrix.fvec.x);
194 fixmulaccum(&q,(pnt->y - View_position.y),View_matrix.fvec.y);
195 fixmulaccum(&q,(pnt->z - View_position.z),View_matrix.fvec.z);
197 return fixquadadjust(&q);