rod.c

/*
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.
*/
/*
 * $Source: Smoke:miner:source:3d::RCS:rod.c $
 * $Revision: 1.2 $
 * $Author: allender $
 * $Date: 1995/09/13 11:31:46 $
 * 
 * Rod routines
 * 
 * $Log: rod.c $
 * Revision 1.2  1995/09/13  11:31:46  allender
 * removed checkmuldiv in PPC implemenation
 *
 * Revision 1.1  1995/05/05  08:52:45  allender
 * Initial revision
 *
 * Revision 1.1  1995/04/17  06:42:08  matt
 * Initial revision
 * 
 * 
 */

#pragma off (unreferenced)
static char rcsid[] = "$Id: rod.c 1.2 1995/09/13 11:31:46 allender Exp $";
#pragma on (unreferenced)

#include "3d.h"
#include "globvars.h"
#include "fix.h"

grs_point blob_vertices[4];
g3s_point rod_points[4];
g3s_point *rod_point_list[] = {&rod_points[0],&rod_points[1],&rod_points[2],&rod_points[3]};

g3s_uvl uvl_list[4] = {	0x0200,0x0200,0,
								0xfe00,0x0200,0,
								0xfe00,0xfe00,0,
								0x0200,0xfe00,0};

//compute the corners of a rod.  fills in vertbuf.
int calc_rod_corners(g3s_point *bot_point,fix bot_width,g3s_point *top_point,fix top_width)
{
	vms_vector delta_vec,top,tempv,rod_norm;
	ubyte codes_and;
	int i;

	//compute vector from one point to other, do cross product with vector
	//from eye to get perpendiclar

	vm_vec_sub(&delta_vec,&bot_point->p3_vec,&top_point->p3_vec);

	//unscale for aspect

	delta_vec.x = fixdiv(delta_vec.x,Matrix_scale.x);
	delta_vec.y = fixdiv(delta_vec.y,Matrix_scale.y);

	//calc perp vector

	//do lots of normalizing to prevent overflowing.  When this code works,
	//it should be optimized

	vm_vec_normalize(&delta_vec);

	vm_vec_copy_normalize(&top,&top_point->p3_vec);

	vm_vec_cross(&rod_norm,&delta_vec,&top);

	vm_vec_normalize(&rod_norm);

	//scale for aspect

	rod_norm.x = fixmul(rod_norm.x,Matrix_scale.x);
	rod_norm.y = fixmul(rod_norm.y,Matrix_scale.y);

	//now we have the usable edge.  generate four points

	//top points

	vm_vec_copy_scale(&tempv,&rod_norm,top_width);
	tempv.z = 0;

	vm_vec_add(&rod_points[0].p3_vec,&top_point->p3_vec,&tempv);
	vm_vec_sub(&rod_points[1].p3_vec,&top_point->p3_vec,&tempv);

	vm_vec_copy_scale(&tempv,&rod_norm,bot_width);
	tempv.z = 0;

	vm_vec_sub(&rod_points[2].p3_vec,&bot_point->p3_vec,&tempv);
	vm_vec_add(&rod_points[3].p3_vec,&bot_point->p3_vec,&tempv);


	//now code the four points

	for (i=0,codes_and=0xff;i<4;i++)
		codes_and &= g3_code_point(&rod_points[i]);

	if (codes_and)
		return 1;		//1 means off screen

	//clear flags for new points (not projected)

	for (i=0;i<4;i++)
		rod_points[i].p3_flags = 0;

	return 0;
}

//draw a polygon that is always facing you
//returns 1 if off screen, 0 if drew
bool g3_draw_rod_flat(g3s_point *bot_point,fix bot_width,g3s_point *top_point,fix top_width)
{
	if (calc_rod_corners(bot_point,bot_width,top_point,top_width))
		return 0;

	return g3_draw_poly(4,rod_point_list);

}

//draw a bitmap object that is always facing you
//returns 1 if off screen, 0 if drew
bool g3_draw_rod_tmap(grs_bitmap *bitmap,g3s_point *bot_point,fix bot_width,g3s_point *top_point,fix top_width,fix light)
{
	if (calc_rod_corners(bot_point,bot_width,top_point,top_width))
		return 0;

	uvl_list[0].l = uvl_list[1].l = uvl_list[2].l = uvl_list[3].l = light;

	return g3_draw_tmap(4,rod_point_list,uvl_list,bitmap);
}

#ifndef __powerc
int checkmuldiv(fix *r,fix a,fix b,fix c);
#endif

//draws a bitmap with the specified 3d width & height 
//returns 1 if off screen, 0 if drew
bool g3_draw_bitmap(vms_vector *pos,fix width,fix height,grs_bitmap *bm)
{
#ifndef __powerc
	g3s_point pnt;
	fix t,w,h;

	if (g3_rotate_point(&pnt,pos) & CC_BEHIND)
		return 1;

	g3_project_point(&pnt);

	if (pnt.p3_flags & PF_OVERFLOW)
		return 1;

	if (checkmuldiv(&t,width,Canv_w2,pnt.p3_z))
		w = fixmul(t,Matrix_scale.x);
	else
		return 1;

	if (checkmuldiv(&t,height,Canv_h2,pnt.p3_z))
		h = fixmul(t,Matrix_scale.y);
	else
		return 1;

	blob_vertices[0].x = pnt.p3_sx - w;
	blob_vertices[0].y = blob_vertices[1].y = pnt.p3_sy - h;
	blob_vertices[1].x = blob_vertices[2].x = pnt.p3_sx + w;
	blob_vertices[2].y = pnt.p3_sy + h;

	scale_bitmap(bm,blob_vertices);

	return 0;
#else
	g3s_point pnt;
	fix w,h;
	double fz;

	if (g3_rotate_point(&pnt,pos) & CC_BEHIND)
		return 1;

	g3_project_point(&pnt);

	if (pnt.p3_flags & PF_OVERFLOW)
		return 1;

	if (pnt.p3_z == 0)
		return 1;
		
	fz = f2fl(pnt.p3_z);
	w = fixmul(fl2f(((f2fl(width)*fCanv_w2) / fz)), Matrix_scale.x);
	h = fixmul(fl2f(((f2fl(height)*fCanv_h2) / fz)), Matrix_scale.y);

	blob_vertices[0].x = pnt.p3_sx - w;
	blob_vertices[0].y = blob_vertices[1].y = pnt.p3_sy - h;
	blob_vertices[1].x = blob_vertices[2].x = pnt.p3_sx + w;
	blob_vertices[2].y = pnt.p3_sy + h;

	scale_bitmap(bm,blob_vertices);

	return 0;
#endif
}