#include #include "rtd.h" #include "extern.h" #include "macros.h" int d_bug = FALSE; double findo (m, s) /* finds where a ray inside the ball exits. */ struct mat *m; struct sphere_data *s; { /* foops id the rotated position vector. */ struct vector foops; double t; MTV (foops, (*m), s -> cent); /* see if it hits the ball (it better)*/ t = s -> rad * s -> rad - foops.y * foops.y - foops.z * foops.z; if (t > 0) t = foops.x + sqrt (t); else t = 0; /* return how far along the ray you were when you hit */ return (t); } double find (m, s)/* finds whether a ray hits a ball*/ struct mat *m; struct sphere_data *s; { struct vector foops; double t; MTV (foops, (*m), s -> cent); t = s -> rad * s -> rad - foops.y * foops.y - foops.z * foops.z; if (t > 0) t = foops.x - sqrt (t); else t = 0; return (t); } double finds (m, s)/* finds if a ball is between a point and a lightsource. Returns how obscuring the ball is */ struct mat *m; struct sphere_data *s; { struct vector foops; double t; MTV (foops, (*m), s -> cent); t = s -> rad - sqrt (foops.y * foops.y + foops.z * foops.z); if (t > 0) t = t / foops.x; else t = 0; return (t); } double shadow (p,objid)/* finds if a point is in a shadow, or if it is on edge */ struct vector *p; int objid; { struct mat trans; struct sphere_data ss; struct vector d, temp, new; struct ray r; struct obj_link *ptr, *three_dda(), *three_next(); struct object_data *c; struct vector intersection_pts; int i; double l, k, x, y, z, find_facet(), finds (); int sead_x, sead_y, sead_z; double bound_x, bound_y, bound_z; l = 0.0; c = NULL; SV (d, light_source.cent, (*p)); d.l = LEN (d); d.xzl = XZL (d); mt (&(d), &trans); MV(p->x, p->y, p-> z, r.org); MV(d.x, d.y, d.z, r.dir); ptr = three_dda(&r, &sead_x, &sead_y, &sead_z); r.src = objid; while (ptr != NULL) { while (ptr != NULL) { if (ptr->the_object->type == SPHERE_TYPE) { ss.rad = ptr->the_object->object.sphere.rad; SV (ss.cent, ptr->the_object->object.sphere.cent, (*p)); if ((k = finds (&trans, &ss)) > l) { c = ptr->the_object; l = k; } /* k > l */ } /* end of if SPHERE_TYPE */ else{ if((k=find_facet(ptr->the_object,&r,&intersection_pts))>0.0) { if (0.9>l) {l = 0.9; c = ptr->the_object;} /* facets are very occlusive in this code, snicker snicker */ } } ptr = ptr->next_obj; } /* end of inner while */ ptr = three_next(&sead_x, &sead_y, &sead_z); } /* end of outer while */ if (c == NULL) k = 200.0; else { k = 1.0 - l / ((light_source.rad) / (d.l)); if (k < 0.0) k = 0.0; k *= 200.0; } return (k); } /* find if a vector intersects a triangle in three space */ double find_facet(ptr, r, intersect_pt) struct object_data *ptr; struct ray *r; struct vector *intersect_pt; { double x, y, z; double t, d, x5, y5, z5, divisor; struct vector v1, v2, vec1, vec2, vec3, norm, new; if (ptr->id == r->src) return(0.0); /* if the ray began at the current object then we should have ret'd above */ MV(ptr->object.facet.point[0].x, ptr->object.facet.point[0].y, ptr->object.facet.point[0].z, vec1); MV(ptr->object.facet.point[1].x, ptr->object.facet.point[1].y, ptr->object.facet.point[1].z, vec2); MV(ptr->object.facet.point[2].x, ptr->object.facet.point[2].y, ptr->object.facet.point[2].z, vec3); MV(ptr->object.facet.normal.x, ptr->object.facet.normal.y, ptr->object.facet.normal.z, norm); norm.xzl = ptr->object.facet.normal.xzl; norm.l = ptr->object.facet.normal.l; MV(r->dir.x,r->dir.y,r->dir.z,new); new.l = LEN(r->dir); if (acos(DOT(norm,new)/(norm.l*new.l)) <= (double)(3.14159265358/2.0)) return(0.0); /*if angle twixt ray and normal is greater than pi/2 we should have returned */ SCMLT((1.0/norm.l), norm); divisor = DOT(norm, r->dir); if (divisor != 0) { t = (DOT(norm, vec1) - DOT(norm, r->org)) / divisor; MV(r->dir.x, r->dir.y, r->dir.z, new); new.l = LEN(new); SCMLT(t, new); t = new.l; AV((*intersect_pt), r->org, new); if (point_inclusion(intersect_pt, &vec1, &vec2, &vec3)) /* we have an intersection */ { if (d_bug) { printf("FACET INTERSECTION t= %5.2f\n", t); printf(" i_pt x = %5.2f y = %5.2f z = %5.2f\n", intersect_pt->x, intersect_pt->y, intersect_pt->z); } return(t); } else return(0.0); } else return(0.0); } /* end of find_facet */ int HALF_PLANE(x,y,x1,y1,x2,y2) /*----------------------------------------------------+ | A FUNCTION TO CHARACTERIZE WHICH SIDE OF THE | | LINE DETERMINED BY (X1,Y1) AND (X2,Y2) THE POINT | | (X,Y) LIES | +----------------------------------------------------*/ float x,y,x1,y1,x2,y2; { float a,b; short c; if (d_bug == TRUE ) printf("\n HALF_PLANE(%5.2f,%5.2f,%5.2f,%5.2f,%5.2f,%5.2f",x,y,x1,y1,x2,y2); a = (x - x1) * (y2 - y1); b = (x2 - x1) * (y - y1); if ( a > b ) c = 1; else if ( a < b ) c = -1; else c = 0; if (d_bug) printf("\nleaving half plane and result is %d",c); return(c); } int point_inclusion(intersect_pt, vec1, vec2, vec3) struct vector *intersect_pt, *vec1, *vec2, *vec3; { double xtmp0, xtmp1, xtmp2, ytmp0, ytmp1, ytmp2, a, x, y, z, mindir, dx, dy, dz; int dummy; dummy = FALSE; /* find change in x, y, and z coordinates */ dx = fabs(NUM_MAX(vec1->x, NUM_MAX(vec2->x, vec3->x)) - NUM_MIN(vec1->x, NUM_MIN(vec2->x, vec3->x))); dy = fabs(NUM_MAX(vec1->y, NUM_MAX(vec2->y, vec3->y)) - NUM_MIN(vec1->y, NUM_MIN(vec2->y, vec3->y))); dz = fabs(NUM_MAX(vec1->z, NUM_MAX(vec2->z, vec3->z)) - NUM_MIN(vec1->z, NUM_MIN(vec2->z, vec3->z))); /* find smallest change in magnitude */ /* this will let us look at the largest */ /* possible plane */ mindir = NUM_MIN(dx, NUM_MIN(dy, dz)); if (mindir == dx) { x = intersect_pt->z; y = intersect_pt->y; xtmp2 = vec3->z; xtmp1 = vec2->z; xtmp0 = vec1->z; ytmp2 = vec3->y; ytmp1 = vec2->y; ytmp0 = vec1->y; } else { if (mindir == dy) { x = intersect_pt->x; y = intersect_pt->z; xtmp2 = vec3->x; xtmp1 = vec2->x; xtmp0 = vec1->x; ytmp2 = vec3->z; ytmp1 = vec2->z; ytmp0 = vec1->z; } else { x = intersect_pt->x; y = intersect_pt->y; xtmp2 = vec3->x; xtmp1 = vec2->x; xtmp0 = vec1->x; ytmp2 = vec3->y; ytmp1 = vec2->y; ytmp0 = vec1->y; } } /* bounding box test for possible intersection points */ if ( ((x - NUM_MAX(xtmp2,NUM_MAX(xtmp1,xtmp0))) > ROUNDOFF) || ((NUM_MIN(xtmp2,NUM_MIN(xtmp1,xtmp0)) - x ) > ROUNDOFF) || (( y - NUM_MAX(ytmp2,NUM_MAX(ytmp1,ytmp0)) ) > ROUNDOFF) || ((NUM_MIN(ytmp2,NUM_MIN(ytmp1,ytmp0)) - y ) > ROUNDOFF)) { if (d_bug) printf("\nleaving inside and result is %d",dummy); return(dummy); } /* see if point is contained in the correct half planes */ /* defined by the triangle */ if ( HALF_PLANE(x,y,xtmp2,ytmp2,xtmp1,ytmp1) != HALF_PLANE(xtmp0,ytmp0,xtmp2,ytmp2,xtmp1,ytmp1) ) { if (d_bug) printf("\nleaving inside(1st half plane) and result is %d",dummy); return(dummy); } if ( HALF_PLANE(x,y,xtmp1,ytmp1,xtmp0,ytmp0) != HALF_PLANE(xtmp2,ytmp2,xtmp1,ytmp1,xtmp0,ytmp0) ) { if (d_bug) printf("\nleaving inside(2nd half plane) and result is %d",dummy); return(dummy); } if ( HALF_PLANE(x,y,xtmp0,ytmp0,xtmp2,ytmp2) == HALF_PLANE(xtmp1,ytmp1,xtmp0, ytmp0,xtmp2,ytmp2)) dummy = TRUE; else dummy = FALSE; if (d_bug) printf("\nleaving inside at end and result is %d",dummy); return(dummy); }