public bool trace(RayContext rayContext)
{
double maxt = rayContext.ray.maxt;
bool haveIntersection = false;
foreach (GeomPrimitive primitive in m_primitives)
{
if (rayContext.ignorePrimitive == primitive)
continue; //skip this primitive
IntersectionData hitData = new IntersectionData();
if (primitive.intersect(rayContext.ray, hitData))
{
if (maxt > hitData.hitT && hitData.hitT > rayContext.ray.mint)
{
maxt = hitData.hitT;
rayContext.hitData = hitData;
rayContext.hitData.hitPrimitive = primitive;
haveIntersection = true;
}
if (haveIntersection)
{
rayContext.hitData.hitPos = rayContext.ray.p + rayContext.ray.dir * rayContext.hitData.hitT;
}
}
}//foreach
return haveIntersection;
}
public override bool intersect( Ray ray, IntersectionData hitData )
{
Vector3 d = ray.dir;
Vector3 p = ray.p;
//лъчът преминава в локални координати на сферата
p = p - center;
double A = d * d;
double B = 2 * (d * p);
double C = (p * p) - (radius * radius);
//връщаме лъча в коодинати на сцената
p = p + center;
double D = (B * B) - (4 * A * C);
if (D < 0)
return false;
else
D = System.Math.Sqrt(D);
double t0 = (-B - D) / (2 * A);
double t1 = (-B + D) / (2 * A);
if (t1 < t0)
t0 = t1;
hitData.hitT = t0;
Vector3 wp = p + d * t0;
hitData.hitPos = wp;
hitData.hitNormal = wp - center;
hitData.hitNormal.normalize();
double u = (System.Math.PI + System.Math.Atan2(wp.z - center.z, wp.x - center.x)) / (System.Math.PI * 2);
double v = 1.0 - ((System.Math.PI / 2) + System.Math.Asin((wp.y - center.y) / radius)) / System.Math.PI;
hitData.textureUVW = new Vector3(u, v, 0);
return true;
}
public abstract bool intersect( Ray ray, IntersectionData hitData );
public override bool intersect( Ray ray, IntersectionData hitData )
{
Vector3 e1, e2;
e1 = v[1] - v[0];// e1 = edge v0 to v1
e2 = v[2] - v[0];// e2 = edge v0 to v2
Vector3 pvec = ray.dir ^ e2;// pvec = cross(dir,e2)
double det = e1 * pvec;// determinant = dot(e1,pvec)
if (det < 1e-6f && det > -1e-6f) return false; // if det close to zero -> ray lies in the plane
double inv_det = 1.0f / det;// inverse determinant
Vector3 tvec = ray.p - v[0];// distance v0 to ray origin
double u = inv_det * (tvec * pvec);// u = dot(tvec,pvec) / det
if (u < -1e-6f || u > (1.0f + 1e-6f)) return false;// if u outside triangle return
Vector3 qvec = tvec ^ e1;// qvec = cross(tvec,e1)
double t = inv_det * (e2 * qvec);// t = dot(e2,qvec) / det
if (t < ray.mint || t > ray.maxt) return false;// return false if t is outside range
double uvV = inv_det * (ray.dir * qvec);// v = dot(dir,qvec) / det
if (uvV < -1e-6f || (u + uvV) > (1.0f + 1e-6f)) return false;// if v outside triangle return
hitData.hitT = t;
hitData.hitNormal = e1 ^ e2;
hitData.hitNormal.normalize();
hitData.textureUVW = ((1 - u - uvV) * tc[0]) + (u * tc[1]) + (uvV * tc[2]);
hitData.shaderID = shaderID;
return true;
}
public void GetIntersection(
Vector3 rayOrigin, Vector3 rayDirection, GeomPrimitive lastHit,
out GeomPrimitive pHitObject, Vector3 pStart, RayContext rayContext)
{
//hitPosition = null;
pHitObject = null;
// is branch: step through subcells and recurse
if (isBranch)
{
//if (pStart == null)
// pStart = rayOrigin;
// find which subcell holds ray origin (ray origin is inside cell)
int subCell = 0;
for (int i = 3; i-- > 0; )
{
// compare dimension with center
if (pStart[i] >= ((bound[i] + bound[i + 3]) * 0.5f))
subCell |= 1 << i;
}
// step through intersected subcells
Vector3 cellPosition = new Vector3(pStart);
for (; ; )
{
if (null != spatial[subCell])
{
// intersect subcell
spatial[subCell].GetIntersection(rayOrigin, rayDirection, lastHit, out pHitObject, cellPosition, rayContext);
// exit if item hit
if (null != pHitObject)
break;
}
// find next subcell ray moves to
// (by finding which face of the corner ahead is crossed first)
int axis = 2;
float[] step = new float[3]; // todo - move this allocation?
for (int i = 3; i-- > 0; axis = step[i] < step[axis] ? i : axis)
{
bool high = ((subCell >> i) & 1) != 0;
float face = (rayDirection[i] < 0.0f) ^ high ? bound[i + ((high ? 1 : 0) * 3)] : (bound[i] + bound[i + 3]) * 0.5f;
// distance to face
// (div by zero produces infinity, which is later discarded)
step[i] = (float)(face - rayOrigin[i]) / (float)rayDirection[i];
}
// leaving branch if: subcell is low and direction is negative,
// or subcell is high and direction is positive
if ((((subCell >> axis) & 1) != 0) ^ (rayDirection[axis] < 0.0f))
break;
// move to (outer face of) next subcell
cellPosition = rayOrigin + (rayDirection * step[axis]);
subCell = subCell ^ (1 << axis);
}
}
else
{ // is leaf: exhaustively intersect contained items
//float nearestDistance = float.MaxValue;
// step through items
foreach (GeomPrimitive item in triangles)
{
if (rayContext.ignorePrimitive == item)
continue; //skip this primitive
if (item == lastHit)
continue; //skip this primitive
IntersectionData hitData = new IntersectionData();
if (item.intersect(rayContext.ray, hitData))
{
// check intersection is inside cell bound (with tolerance)
Vector3 hit = rayOrigin + (rayDirection * hitData.hitT);
float t = TOLERANCE;
if ((bound[0] - hit[0] <= t) && (hit[0] - bound[3] <= t) &&
(bound[1] - hit[1] <= t) && (hit[1] - bound[4] <= t) &&
(bound[2] - hit[2] <= t) && (hit[2] - bound[5] <= t))
{
pHitObject = item;
//nearestDistance = distance;
//hitPosition = hit;
rayContext.hitData = hitData;
rayContext.hitData.hitPrimitive = item;
rayContext.hitData.hitPos = rayContext.ray.p + rayContext.ray.dir * rayContext.hitData.hitT;
rayContext.hitData.hasIntersection = true;
}
}
}
}
}
