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/******************************************************************/
/* This file is part of the homework assignments for CSCI-427/527 */
/* at The College of William & Mary and authored by Pieter Peers. */
/* No part of this file, whether altered or in original form, can */
/* be distributed or used outside the context of CSCI-427/527 */
/* without consent of either the College of William & Mary or */
/* Pieter Peers. */
/******************************************************************/
#include <cmath>
#include "constants.h"
#include "spotLightsource.h"
//////////////////
// Constructors //
//////////////////
spotLightsource::spotLightsource(const vec3d& position, const vec3d& direction, float cutoffDegrees, float sharpness, const color& power, const vec3d& attenuation)
{
_position = position;
_direction = normalize(direction);
_cutoff = cos(cutoffDegrees * PI / 180.0f);
_sharpness = sharpness;
_power = power;
_attenuation = attenuation;
}
/////////////
// Methods //
/////////////
lightSample spotLightsource::intensityAt(const vec3d& point) const
{
// HW5: Implement this. Computes the intensity from a spot
// light source toward the 'point' taking in account
// attenuation, cutoff angle, and sharpness.
// Modifies: nothing.
// Returns: light sample (pass 1) direction, 2) power/color
// of the incident lighting, and 3) distance between
// the light source and the point).
vec3d direction = (point - _position).normalize();
float dl_dot = direction.dot(_direction);
float distance = _position.distance(point);
color emittance;
if (dl_dot > _cutoff) {
emittance = _power * pow(dl_dot, _sharpness) / (
_attenuation.x +
_attenuation.y * distance +
_attenuation.z * _position.squared_distance(point));
}
else {
emittance = color(0);
}
return lightSample(direction, emittance, distance);
}
/////////////////////
// Private Methods //
/////////////////////
void spotLightsource::_print(std::ostream& s) const
{
s << "Spot Lightsource: position=" << _position << ", direction=" << _direction << ", cutoff=" << (acos(_cutoff)*180.0f/PI) << ", sharpness=" << _sharpness << ", power=" << _power << ", attenuation=" << _attenuation;
}
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