Celestin Apprentice 4/Apprentice-Release4.iso/Source Code/C/Applications/MacWT 0.9/wt Source/object.c

C/C++ Source or Header | 1995-10-10 | 5.3 KB | 246 lines | [TEXT/CWIE]

/*
**  MacWT -- a 3d game engine for the Macintosh
**  © 1995, Bill Hayden and Nikol Software
**  Free for non-commercial use - address questions to the e-mail address below
**
**  Mail:           [e-mail] (Bill Hayden)
**    MacWT FTP site: ftp.circa.ufl.edu/pub/software/ufmug/mirrors/LocalSW/Hayden/
**  WWW Page:       http://grove.ufl.edu:80/~nikolsw
**
**    All of the above addresses are due to changes sometime in 1996, so stay tuned
**
**  based on wt, by Chris Laurel
**
**  This program is distributed in the hope that it will be useful,
**  but WITHOUT ANY WARRANTY; without even the implied warranty of
**  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*/



#include <stdlib.h>
#include "wt.h"
#include "error.h"
#include "wtmem.h"
#include "fixed.h"
#include "view.h"
#include "table.h"
#include "list.h"
#include "framebuf.h"
#include "texture.h"
#include "world.h"
#include "object.h"
#include "collision.h"


#define FP_ZERO(f) (((f) > -1.0e-5) && ((f) < 1.0e-5))

double gravity = -0.05;
Bounds    WorldBounds = {0.0, 0.0, 0.0, 0.0};



Object *new_object(double mass, double xsize, double ysize, double height, double drag)
{
    Object *o;
    short    i = MAX_IMAGES;

    o = (Object *)wtmalloc(sizeof(Object));
    o->mass = mass;
    o->xsize = xsize;
    o->ysize = ysize;
    o->height = height;
    o->drag = drag;

    o->dx = o->dy = o->dz = 0.0;
    o->angle = 0.0;
    o->angular_v = 0.0;

    o->region = NULL;

    while (i--)
        o->image[i] = NULL;

    o->num_images = 0;        // No images yet
    o->cur_image = 0;        // Undefined w/o images

    o->frameticks = 0;        // Auto-animate
    o->triggerticks = 0;
    o->reference = 0;

    return o;
}


void object_update(Object *o)
{
    if (o->drag != 1.0)
        {
        o->dx *= o->drag;
        o->dy *= o->drag;
        o->angular_v *= o->drag;
        }

    o->x += o->dx;
    o->y += o->dy;
    o->z += o->dz;
    o->angle += o->angular_v;

    // Animate object

    if (o->num_images)
        {
        long    secs;

        if (!o->frameticks)    // Auto-animate
            AdvanceFrame(o);
        else
            {
            secs = LMGetTicks();
            if (secs >= o->triggerticks)
                {
                AdvanceFrame(o);
                o->triggerticks = secs + o->frameticks;
                }
            }
        }

    // Get the object's region

    if (!FP_ZERO(o->dx) || !FP_ZERO(o->dy) || (o->region == NULL))
        o->region = in_region(o->world, FLOAT_TO_FIXED(o->x /*+ (o->dx * o->xsize)*/), FLOAT_TO_FIXED(o->y /*+ (o->dy * o->ysize)*/) );

    // Prevent the object from leaving the world entirely

    if (o->x < WorldBounds.left + o->xsize)
        o->x = WorldBounds.left + o->xsize;
    else if (o->x > WorldBounds.right - o->xsize)
        o->x = WorldBounds.right - o->xsize;

    if (o->y < WorldBounds.top + o->ysize)
        o->y = WorldBounds.top + o->ysize;
    else if (o->y > WorldBounds.bottom - o->ysize)
        o->y = WorldBounds.bottom - o->ysize;


    // Prevent the object from rising through the ceiling

    if (o->z + o->height > FIXED_TO_FLOAT(o->region->ceiling))
        {
        o->z = FIXED_TO_FLOAT(o->region->ceiling) - o->height;
        o->dz = 0.0;
        }


    // Prevent the object from passing through walls

    CheckCollision(o);


    // Prevent the object from sinking through the floor

    if (o->z < FIXED_TO_FLOAT(o->region->floor))
        {
        o->z = FIXED_TO_FLOAT(o->region->floor);
        o->dz = 0.0;
        }
    else
        o->dz += gravity;    // only drop if not already on the floor
}



void object_apply_force(Object *o, double fx, double fy, double fz)
{
    o->dx += fx / o->mass;
    o->dy += fy / o->mass;
    o->dz += fz / o->mass;
}



/* This is a really simple model of torque--since there's no information in
**   the object about mass distribution, there is no moment of inertia.  For
**   lack of something better, we just use the mass.
*/
void object_apply_torque(Object *o, double torque)
{
     o->angular_v += torque / o->mass;
}


/* Set the position of an object in a world--setting an object's position
**   should only be done by calling this function; it should never be
**   set directly by modifying structure fields.
*/
extern void object_set_position(Object *o, double x, double y, double z)
{
    if (x != o->x || y != o->y || o->region == NULL)
        o->region = in_region(o->world, FLOAT_TO_FIXED(x), FLOAT_TO_FIXED(y));

    o->x = x;
    o->y = y;
    o->z = z;
}


void add_object(World *w, Object *o)
{
     /* Add an object to a world.  The object is added to the beginning of
     **   the list.  When an object is destroyed, we search for it in the
     **   the list starting from the beginning.  This ends up being quite
     **   efficient since the object being destroyed is likely to have
     **   been created recently.
     */
     add_node(w->objects, o);

     o->world = w;
}


Boolean remove_object(World *w, Object *o)
{
    List *l;

    l = scan_list(w->objects, o, find_node);
    if (l == NULL)
        return FALSE;
    else
        {
        remove_node(l);
        return TRUE;
        }
}



/* Derive a view from an object.  Assume that some fields of the view struct
**   have already been filled in:  view_plane_size, view_arc, and others that
**   cannot be determined from the object.
*/
void object_view(Object *o, View *v)
{
     v->x = FLOAT_TO_FIXED(o->x);
     v->y = FLOAT_TO_FIXED(o->y);
     v->height = FLOAT_TO_FIXED(o->z + o->height);
     v->angle = FLOAT_TO_FIXED(o->angle);
}



void AdvanceFrame(Object *o)
{
    o->cur_image = (o->cur_image + 1) % o->num_images;
}



Boolean AddFrame(Object *o, char *TextureName)
{
    if (o->num_images >= MAX_IMAGES)
        return FALSE;

    o->image[o->num_images++] = read_texture_file(TextureName);
    return TRUE;
}