RNClassID R3Span::
Clip(const R3Plane& plane)
{
// Characterize endpoints with respect to plane
RNScalar d1 = R3SignedDistance(plane, Start());
RNScalar d2 = R3SignedDistance(plane, End());
// Clip span to plane
if (RNIsNegative(d1)) {
if (RNIsNegative(d2)) {
// Both points are below plane ???
Reset(Start(), Start());
return RN_NULL_CLASS_ID;
}
else if (RNIsPositive(d2)) {
// Start is below, end is above -- move start to plane
Reset((Start() * d2 + End() * -d1) / (d2 - d1), End());
return R3_SPAN_CLASS_ID;
}
else {
// Start is below, end is on -- move start to end
Reset(End(), End());
return R3_POINT_CLASS_ID;
}
}
else if (RNIsPositive(d1)) {
if (RNIsNegative(d2)) {
// Start is above, end is below -- move end to plane
Reset(Start(), (Start() * -d2 + End() * d1) / (d1 - d2));
return R3_SPAN_CLASS_ID;
}
else {
// Start is above, end is on or above
return R3_SPAN_CLASS_ID;
}
}
else {
if (RNIsNegative(d2)) {
// Start is on, end is below -- move end to start
Reset(Start(), Start());
return R3_POINT_CLASS_ID;
}
else {
// Start is on, end is on or above
return R3_SPAN_CLASS_ID;
}
}
}
RNRgb R3PointLight::
Reflection(const R3Brdf& brdf, const R3Point& eye,
const R3Point& point, const R3Vector& normal) const
{
// Check if light is active
if (!IsActive()) return RNblack_rgb;
// Get material properties
const RNRgb& Dc = brdf.Diffuse();
const RNRgb& Sc = brdf.Specular();
RNScalar s = brdf.Shininess();
// Get light properties
RNScalar I = IntensityAtPoint(point);
R3Vector L = DirectionFromPoint(point);
const RNRgb& Ic = Color();
// Compute geometric stuff
RNScalar NL = normal.Dot(L);
if (RNIsNegativeOrZero(NL)) return RNblack_rgb;
R3Vector R = (2.0 * NL) * normal - L;
R3Vector V = eye - point;
V.Normalize();
RNScalar VR = V.Dot(R);
// Compute diffuse reflection
RNRgb rgb = (I * NL) * Dc * Ic;
// Compute specular reflection
if (RNIsPositive(VR)) rgb += (I * pow(VR,s)) * Sc * Ic;
// Return total reflection
return rgb;
}
RNLength R2Distance(const R2Line& line, const R2Span& span)
{
// Return distance from span to line
RNScalar d = R2SignedDistance(line, span);
if (RNIsPositive(d)) return d;
else if (RNIsNegative(d)) return -d;
else return 0.0;
}
RNLength R2SignedDistance(const R2Line& line, const R2Span& span)
{
// Return signed distance from line to span
RNLength d1 = R2SignedDistance(line, span.Start());
if (RNIsPositive(d1)) {
// Start point is above line
RNLength d2 = R2SignedDistance(line, span.End());
if (RNIsPositive(d2)) return ((d1 > d2) ? d2 : d1);
else return 0.0;
}
else if (RNIsNegative(d1)) {
// Start point is below line
RNLength d2 = R2SignedDistance(line, span.End());
if (RNIsNegative(d2)) return ((d1 > d2) ? d1 : d2);
else return 0.0;
}
else {
// Start point is on line
return 0.0;
}
}
RNLength R2Distance(const R2Point& point, const R2Span& span)
{
// Check span
if (RNIsZero(span.Length())) return R2Distance(point, span.Start());
// Check if start point is closest
R2Vector v1 = point - span.Start();
RNScalar dir1 = v1.Dot(span.Vector());
if (RNIsNegative(dir1)) return v1.Length();
// Check if end point is closest
R2Vector v2 = point - span.End();
RNScalar dir2 = v2.Dot(span.Vector());
if (RNIsPositive(dir2)) return v2.Length();
// Return distance from point to span line
return R2Distance(point, span.Line());
}
