Graphics Plus/Graphics Plus.iso/msdos/raytrace/rayshade/src/texture.c

C/C++ Source or Header | 1991-07-18 | 5.1 KB | 213 lines

/*
 * texture.c
 *
 * Copyright (C) 1989, 1991, Craig E. Kolb
 * All rights reserved.
 *
 * This software may be freely copied, modified, and redistributed
 * provided that this copyright notice is preserved on all copies.
 *
 * You may not distribute this software, in whole or in part, as part of
 * any commercial product without the express consent of the authors.
 *
 * There is no warranty or other guarantee of fitness of this software
 * for any purpose.  It is provided solely "as is".
 *
 * $Id: texture.c,v 4.0 91/07/17 14:44:11 kolb Exp Locker: kolb $
 *
 * $Log:    texture.c,v $
 * Revision 4.0  91/07/17  14:44:11  kolb
 * Initial version.
 *
 */
#include "texture.h"

/*
 * Transformation structures used to map from texture space to
 * model/primitive/world space.
 */
Trans prim2model, model2text, prim2text, world2text;

#define ApplyMapping(m,o,p,n,c,u,v)    (*m->method)(m, o, p, n, c, u, v)

Texture *
TextCreate(data, meth)
TextRef data;
void (*meth)();
{
    Texture *res;

    res = (Texture *)share_calloc(1, sizeof(Texture));
    res->data = data;
    res->method = meth;
    res->trans = (Trans *)NULL;
    res->next = (Texture *)NULL;
    res->animtrans = FALSE;
    return res;
}

/*
 * Apply appropriate textures to a surface.
 */
void
TextApply(tlist, prim, ray, pos, norm, gnorm, surf, p2model, world2model)
Texture *tlist;                /* Textures */
Geom *prim;
Ray *ray;
Vector *pos, *norm, *gnorm;        /* pos, shading norm, geo. norm */
Surface *surf;
Trans *p2model, *world2model;
{
    Vector ptmp;
    Texture *ttmp;

    prim2model = *p2model;
    /*
     * Walk down texture list, applying each in turn.
     */
    for (ttmp = tlist; ttmp; ttmp = ttmp->next) {
        /*
         * Make copies of pos & ray to pass to the texturing function.
         */
        ptmp = *pos;
        if (ttmp->trans) {
            /*
             * 'take' the inverse of ttmp->trans, since
             * transforming a texture means applying the
             * inverse of the transformation
             * to the point of intersection, etc.
             */
            if (ttmp->animtrans) {
                /*
                 * Resolve animated associations.
                 * We currently do not store a time
                 * for the texture, so we can't know if
                 * we're already resolved for the current
                 * ray->time.
                 */
                TransResolveAssoc(ttmp->trans);
                TransComposeList(ttmp->trans, &model2text);
                TransInvert(&model2text, &model2text);
            } else
                TransInvert(ttmp->trans, &model2text);
            /*
             * We compose ttmp->trans, which maps from model to
             * texture space, with prim2model and world2model
             * to get prim2text and world2text.
             */
            TransCompose(&model2text, &prim2model, &prim2text);
            TransCompose(&model2text, world2model, &world2text);
            /*
             * Transform intersection point to texture space.
             * Ray and normal are passed in model space.
             */
            ModelPointToText(&ptmp);
        } else {
            /*
              * By default, texture and model space are identical.
              */
            TransInit(&model2text);
            TransCopy(&prim2model, &prim2text);
            TransCopy(world2model, &world2text);
        }

        /*
         * Call texture function.
         */
        (*ttmp->method) (ttmp->data,prim,ray,&ptmp,norm,gnorm,surf);
    }
}

/*
 * Compute UV at 'pos' on given primitive.
 */
TextToUV(mapping, prim, pos, norm, u, v, dpdu, dpdv)
Mapping *mapping;
Geom *prim;
Vector *pos, *norm, *dpdu, *dpdv;
Float *u, *v;
{
    Vec2d uv;
    Vector ptmp;
    RSMatrix t;

    ptmp = *pos;

    if (mapping->flags & PRIMSPACE) {
        /*
          * Convert point and normal to primitive space.
          */
        TextPointToPrim(&ptmp);
    } else {
        /*
         * Convert point and normal to object space.
         */
        TextPointToModel(&ptmp);
    }

    ApplyMapping(mapping, prim, &ptmp, norm, &uv, dpdu, dpdv);

    /*
     * Transform UV by model2text.  We set X = u and Y = v,
     * while Z = 0.
     * Although the UV coordinates may be in prim space,
     * we treat them as if they are model-space coords.
     * This is due to the fact that we want the texture
     * to be applied in model space.
     */
    ptmp.x = uv.u;
    ptmp.y = uv.v;
    ptmp.z = 0.;
    PointTransform(&ptmp, &model2text.trans);
    *u = ptmp.x;
    *v = ptmp.y;
    if (dpdu == (Vector *)NULL || dpdv == (Vector *)NULL)
        return;
    /*
     * Here's the ugly part.
     * Build initial UVN-->XYZ matrix...
     */
    ArbitraryMatrix(dpdu->x, dpdu->y, dpdu->z,
             dpdv->x, dpdv->y, dpdv->z,
             norm->x, norm->y, norm->z, 0., 0., 0., &t);
    /*
     * ...transform to model space...
     */
    MatrixMult(&t, &prim2model.trans, &t);
    /*
     * ... apply model2text in UVN space.
     */
    MatrixMult(&model2text.itrans, &t, &t);
    dpdu->x = t.matrix[0][0];
    dpdu->y = t.matrix[0][1];
    dpdu->z = t.matrix[0][2];
    dpdv->x = t.matrix[1][0];
    dpdv->y = t.matrix[1][1];
    dpdv->z = t.matrix[1][2];
    (void)VecNormalize(dpdu);
    (void)VecNormalize(dpdv);
}

/*
 * Append 'text' to the given linked list of textures.
 * Note that 'text' may be a list, too.
 */
Texture *
TextAppend(text, list)
Texture *text, *list;
{
    Texture *tp;

    if (list) {
        /*
         * Walk to the end of the list
         */
        for (tp = list;tp->next ;tp = tp->next)
                ;
        tp->next = text;
        return list;
    }
    /* else */
    return text;
}