ao_helpers.cpp

#include "ao.h"

double vdot(vec v0, vec v1)
{
    return v0.x * v1.x + v0.y * v1.y + v0.z * v1.z;
}

void vcross(vec *c, vec v0, vec v1)
{
    
    c->x = v0.y * v1.z - v0.z * v1.y;
    c->y = v0.z * v1.x - v0.x * v1.z;
    c->z = v0.x * v1.y - v0.y * v1.x;
}

void vnormalize(vec *c)
{
    double length = sqrt(vdot((*c), (*c)));

    if (fabs(length) > 1.0e-17) {
        c->x /= length;
        c->y /= length;
        c->z /= length;
    }
}

unsigned char
clamp(double f)
{
  int i = (int)(f * 255.5);

  if (i < 0) i = 0;
  if (i > 255) i = 255;

  return (unsigned char)i;
}

void
saveppm(const char *fname, int w, int h, unsigned char *img)
{
    FILE *fp;

    fp = fopen(fname, "wb");
    assert(fp);

    fprintf(fp, "P6\n");
    fprintf(fp, "%d %d\n", w, h);
    fprintf(fp, "255\n");
    fwrite(img, w * h * 3, 1, fp);
    fclose(fp);
}