3d/instance.c

   1 /*
   2 THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
   3 SOFTWARE CORPORATION ("PARALLAX").  PARALLAX, IN DISTRIBUTING THE CODE TO
   4 END-USERS, AND SUBJECT TO ALL OF THE TERMS AND CONDITIONS HEREIN, GRANTS A
   5 ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS
   6 IN USING, DISPLAYING,  AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS
   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.
  12 */
  13 /*
  14  *
  15  * Instancing routines
  16  *
  17  */
  18
  19 #ifdef HAVE_CONFIG_H
  20 #include <conf.h>
  21 #endif
  22
  23 #include <stdlib.h>
  24 #include "error.h"
  25
  26 #include "3d.h"
  27 #include "globvars.h"
  28
  29 #define MAX_INSTANCE_DEPTH      5
  30
  31 struct instance_context {
  32         vms_matrix m;
  33         vms_vector p;
  34 } instance_stack[MAX_INSTANCE_DEPTH];
  35
  36 int instance_depth = 0;
  37
  38 //instance at specified point with specified orientation
  39 //if matrix==NULL, don't modify matrix.  This will be like doing an offset
  40 void g3_start_instance_matrix(vms_vector *pos,vms_matrix *orient)
  41 {
  42         vms_vector tempv;
  43         vms_matrix tempm,tempm2;
  44
  45         Assert(instance_depth<MAX_INSTANCE_DEPTH);
  46
  47         instance_stack[instance_depth].m = View_matrix;
  48         instance_stack[instance_depth].p = View_position;
  49         instance_depth++;
  50
  51         //step 1: subtract object position from view position
  52
  53         vm_vec_sub(&tempv,&View_position,pos);
  54
  55
  56         if (orient) {
  57
  58                 //step 2: rotate view vector through object matrix
  59
  60                 vm_vec_rotate(&View_position,&tempv,orient);
  61
  62                 //step 3: rotate object matrix through view_matrix (vm = ob * vm)
  63
  64                 vm_copy_transpose_matrix(&tempm2,orient);
  65
  66                 vm_matrix_x_matrix(&tempm,&tempm2,&View_matrix);
  67                 View_matrix = tempm;
  68         }
  69 }
  70
  71
  72 //instance at specified point with specified orientation
  73 //if angles==NULL, don't modify matrix.  This will be like doing an offset
  74 void g3_start_instance_angles(vms_vector *pos,vms_angvec *angles)
  75 {
  76         vms_matrix tm;
  77
  78         if (angles==NULL) {
  79                 g3_start_instance_matrix(pos,NULL);
  80                 return;
  81         }
  82
  83         vm_angles_2_matrix(&tm,angles);
  84
  85         g3_start_instance_matrix(pos,&tm);
  86
  87 }
  88
  89
  90 //pops the old context
  91 void g3_done_instance()
  92 {
  93         instance_depth--;
  94
  95         Assert(instance_depth >= 0);
  96
  97         View_position = instance_stack[instance_depth].p;
  98         View_matrix = instance_stack[instance_depth].m;
  99 }
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