54 flt VDot(vector *a, vector *b) {  in VDot()  argument
55     return (a->x * b->x + a->y * b->y + a->z * b->z);  in VDot()
58 void VCross(vector *a, vector *b, vector *c) {  in VCross()  argument
59     c->x = (a->y * b->z) - (a->z * b->y);  in VCross()
60     c->y = (a->z * b->x) - (a->x * b->z);  in VCross()
61     c->z = (a->x * b->y) - (a->y * b->x);  in VCross()
79 void VAdd(vector *a, vector *b, vector *c) {  in VAdd()  argument
80     c->x = (a->x + b->x);  in VAdd()
81     c->y = (a->y + b->y);  in VAdd()
82     c->z = (a->z + b->z);  in VAdd()
85 void VSub(vector *a, vector *b, vector *c) {  in VSub()  argument
86     c->x = (a->x - b->x);  in VSub()
87     c->y = (a->y - b->y);  in VSub()
88     c->z = (a->z - b->z);  in VSub()
113 void ColorAddS(color *a, color *b, flt s) {  in ColorAddS()  argument
114     a->r += b->r * s;  in ColorAddS()
115     a->g += b->g * s;  in ColorAddS()
116     a->b += b->b * s;  in ColorAddS()
119 void ColorAccum(color *a, color *b) {  in ColorAccum()  argument
120     a->r += b->r;  in ColorAccum()
121     a->g += b->g;  in ColorAccum()
122     a->b += b->b;  in ColorAccum()
128     a->b *= s;  in ColorScale()