3d/instance.c

   1 /* $Id: instance.c,v 1.6 2005-08-02 06:14:48 chris Exp $ */
   2 /*
   3 THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
   4 SOFTWARE CORPORATION ("PARALLAX").  PARALLAX, IN DISTRIBUTING THE CODE TO
   5 END-USERS, AND SUBJECT TO ALL OF THE TERMS AND CONDITIONS HEREIN, GRANTS A
   6 ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS
   7 IN USING, DISPLAYING,  AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS
   8 SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE
   9 FREE PURPOSES.  IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE
  10 CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES.  THE END-USER UNDERSTANDS
  11 AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.
  12 COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
  13 */
  14 /*
  15  *
  16  * Instancing routines
  17  *
  18  */
  19
  20 #ifdef HAVE_CONFIG_H
  21 #include <conf.h>
  22 #endif
  23
  24 #include <stdlib.h>
  25 #include "error.h"
  26
  27 #include "3d.h"
  28 #include "globvars.h"
  29
  30 #define MAX_INSTANCE_DEPTH      5
  31
  32 struct instance_context {
  33         vms_matrix m;
  34         vms_vector p;
  35 } instance_stack[MAX_INSTANCE_DEPTH];
  36
  37 int instance_depth = 0;
  38
  39 //instance at specified point with specified orientation
  40 //if matrix==NULL, don't modify matrix.  This will be like doing an offset
  41 void g3_start_instance_matrix(vms_vector *pos,vms_matrix *orient)
  42 {
  43         vms_vector tempv;
  44         vms_matrix tempm,tempm2;
  45
  46         Assert(instance_depth<MAX_INSTANCE_DEPTH);
  47
  48         instance_stack[instance_depth].m = View_matrix;
  49         instance_stack[instance_depth].p = View_position;
  50         instance_depth++;
  51
  52         //step 1: subtract object position from view position
  53
  54         vm_vec_sub(&tempv,&View_position,pos);
  55
  56
  57         if (orient) {
  58
  59                 //step 2: rotate view vector through object matrix
  60
  61                 vm_vec_rotate(&View_position,&tempv,orient);
  62
  63                 //step 3: rotate object matrix through view_matrix (vm = ob * vm)
  64
  65                 vm_copy_transpose_matrix(&tempm2,orient);
  66
  67                 vm_matrix_x_matrix(&tempm,&tempm2,&View_matrix);
  68                 View_matrix = tempm;
  69         }
  70 }
  71
  72
  73 //instance at specified point with specified orientation
  74 //if angles==NULL, don't modify matrix.  This will be like doing an offset
  75 void g3_start_instance_angles(vms_vector *pos,vms_angvec *angles)
  76 {
  77         vms_matrix tm;
  78
  79         if (angles==NULL) {
  80                 g3_start_instance_matrix(pos,NULL);
  81                 return;
  82         }
  83
  84         vm_angles_2_matrix(&tm,angles);
  85
  86         g3_start_instance_matrix(pos,&tm);
  87
  88 }
  89
  90
  91 //pops the old context
  92 void g3_done_instance()
  93 {
  94         instance_depth--;
  95
  96         Assert(instance_depth >= 0);
  97
  98         View_position = instance_stack[instance_depth].p;
  99         View_matrix = instance_stack[instance_depth].m;
 100 }
 101
 102