// Returns index of triangle intersected by central axis of lightfield cell's beam
// Returns -1 if no triangle is intersected
private int BeamTriangleSimpleIntersect(Coord4D lfCoord, RenderContext context)
{
// switch to tracing the canonical ray associated with this lightfield entry, instead of the original ray (to avoid biasing values in lightfield)
Vector cellRayStart;
Vector cellRayDir;
lightFieldCache.Coord4DToRay(lfCoord, out cellRayStart, out cellRayDir);
// TODO: once the light field cache 'fills up', do we cease tracing rays? Prove/measure this!
// trace a primary ray against all triangles in scene
// TODO: trace multiple rays to find the triangle with largest cross-section in the beam corresponding to this lightfield cell?
// This may also avoid incorrectly storing 'missing triangle' value when primary ray misses because there are no triangles along central axis of cell's beam.
IntersectionInfo intersection = geometry_subdivided.IntersectRay(cellRayStart, cellRayDir, context);
if (intersection == null)
{
return(-1);
}
else
{
Contract.Assert(intersection.triIndex >= 0);
return(intersection.triIndex);
}
}
/// <summary>
/// Intersect a line segment this object.
/// </summary>
/// <param name="start">The start position of the line segment, in object space.</param>
/// <param name="end">The end position of the line segment, in object space.</param>
/// <returns>Information about the first intersection, or null if no intersection.</returns>
public IntersectionInfo IntersectLineSegment(Vector start, Vector end)
{
// Project the start and end vectors onto the plane normal.
// Note that all distances are in multiples of the normal, NOT in space units!
double startDist = start.DotProduct(_normal);
double endDist = end.DotProduct(_normal);
double lineFrac = (_originDist - startDist) / (endDist - startDist);
if (0.0 <= lineFrac && lineFrac <= 1.0)
{
IntersectionInfo info = new IntersectionInfo();
info.rayFrac = lineFrac;
info.pos = start + (end - start) * lineFrac;
// TODO: not strictly neccessary
info.normal = _normal;
info.color = 0x00ffffff;
// TODO: better parameterisation of the surface
// info.u = info.pos.x;
// info.v = info.pos.z;
return(info);
}
else
{
return(null);
}
}
/// <summary>
/// Intersect a ray against this object.
/// </summary>
/// <param name="start">The start position of the ray, in object space.</param>
/// <param name="dir">The direction of the ray, in object space (not a unit vector).</param>
/// <returns>Information about the nearest intersection, or null if no intersection.</returns>
/// <remarks>Thread safe</remarks>
public IntersectionInfo IntersectRay(Vector start, Vector dir, RenderContext context)
{
// trace ray through underlying geometry
IntersectionInfo info = geometry.IntersectRay(start, dir, context);
// if shadowing is disabled, pass-through the ray intersection
if (!Enabled)
{
return(info);
}
// did ray not hit any geometry?
if (info == null)
{
return(null);
}
byte lightIntensityByte = 255;
if (softShadowCache != null)
{
// Static soft shadows, cached in a 3D texture
currSurfaceNormal = info.normal; // a hack to pass this value to TraceRaysForSoftShadows
lightIntensityByte = softShadowCache.Sample(info.pos);
}
else
{
// Dynamic soft shadows, not cached
lightIntensityByte = (byte)(TraceRaysForSoftShadows(info.pos, info.normal, geometry, context) * 255);
}
info.color = Color.ModulatePackedColor(info.color, lightIntensityByte);
return(info);
}
/// <summary>
/// Intersect a ray against this object.
/// </summary>
/// <param name="start">The start position of the ray, in object space.</param>
/// <param name="dir">The direction of the ray, in object space (not a unit vector).</param>
/// <returns>Information about the nearest intersection, or null if no intersection.</returns>
public IntersectionInfo IntersectRay(Vector start, Vector dir, RenderContext context)
{
numRayTests = 0;
IntersectionInfo closest = new IntersectionInfo();
closest.rayFrac = double.MaxValue;
foreach (IRayIntersectable geometry in _geomList)
{
IntersectionInfo curr = geometry.IntersectRay(start, dir, context);
if (curr != null && curr.rayFrac < closest.rayFrac)
{
closest = curr;
}
numRayTests += geometry.NumRayTests;
RayGeometryTestCount++;
}
if (closest.rayFrac == double.MaxValue)
{
return(null);
}
else
{
return(closest);
}
}
/// <summary>
/// Intersect a ray against this object.
/// </summary>
/// <param name="start">The start position of the ray, in object space.</param>
/// <param name="dir">The direction of the ray, in object space (not a unit vector).</param>
/// <returns>Information about the nearest intersection, or null if no intersection.</returns>
public IntersectionInfo IntersectRay(Vector start, Vector dir, RenderContext context)
{
numRayTests = 0;
IntersectionInfo closest = new IntersectionInfo();
closest.rayFrac = double.MaxValue;
foreach (Plane plane in planes)
{
// Does ray intersect this plane?
IntersectionInfo curr = plane.IntersectRay(start, dir, context);
numRayTests += plane.NumRayTests;
if (curr != null && curr.rayFrac < closest.rayFrac)
{
// Does the intersection point lie on the surface of this box?
if (ContainsPoint(curr.pos))
{
// Yes, so the ray intersects this box.
closest = curr;
}
}
}
if (closest.rayFrac == double.MaxValue)
{
return(null);
}
else
{
return(closest);
}
}
/// <summary>
/// Intersect a ray against this object.
/// </summary>
/// <param name="start">The start position of the ray, in object space.</param>
/// <param name="dir">The direction of the ray, in object space (not a unit vector).</param>
/// <returns>Information about the nearest intersection, or null if no intersection.</returns>
public IntersectionInfo IntersectRay(Vector start, Vector dir, RenderContext context)
{
IntersectionInfo info = plane.IntersectRay(start, dir, context);
if (info == null)
{
return(null);
}
Assert.IsTrue(info.rayFrac >= 0.0, "Ray fraction is negative");
Vector v1ToIntersection = info.pos - vertex1.Position;
double s = v1ToIntersection.DotProduct(edge2Perp) / edge1.DotProduct(edge2Perp);
if (s < 0.0 || s > 1.0)
{
return(null);
}
double t = v1ToIntersection.DotProduct(edge1Perp) / edge2.DotProduct(edge1Perp);
if (s >= 0.0 && t >= 0.0 && s + t <= 1.0)
{
info.color = color;
info.triIndex = TriangleIndex;
return(info);
}
return(null);
}
/// <summary>
/// Calculates ambient occlusion at a point on a surface.
/// </summary>
/// <param name="surface">Information about surface point</param>
/// <param name="geometry">The geometry to be raytraced (both occlusion caster and occlusion receiver)</param>
/// <param name="random">Random number generator to use</param>
/// <returns>Fraction of non-occlusion at surface point (between 0 and 1): 0 = surface point fully occluded by neighbour surfaces; 1 = surface point not occluded at all</returns>
private double CalcAmbientOcclusion(IntersectionInfo surface, Raytrace.IRayIntersectable geometry, RenderContext context)
{
Contract.Ensures(0 <= Contract.Result <double>() && Contract.Result <double>() <= 1);
var random = context.RNG;
var rayStart = surface.pos + surface.normal * ambientOcclusionProbeOffset;
Vector avgEscapedRayDir = new Vector();
int rayEscapeCount = 0;
for (int i = 0; i < ambientOcclusionQuality; i++)
{
// Pick a random direction within the hemisphere around the surface normal
// TODO: works for external surfaces, but some self-intersection on interior surfaces
var rayDir = new Vector(random.NextDouble() * 2 - 1, random.NextDouble() * 2 - 1, random.NextDouble() * 2 - 1);
//rayDir.Normalise();
if (rayDir.DotProduct(surface.normal) < 0)
{
rayDir = -rayDir;
}
// Pick random directions until we find one roughly in the same direction as the surface normal
//Vector rayDir;
//double cosOfAngle;
//do
//{
// rayDir = new Vector(random.NextDouble() * 2 - 1, random.NextDouble() * 2 - 1, random.NextDouble() * 2 - 1);
// rayDir.Normalise();
// cosOfAngle = rayDir.DotProduct(surfaceInfo.normal);
// // force ray to be in the hemisphere around the surface normal
//} while (cosOfAngle < 0.0);
// Fire off ray to check for nearby surface in chosen direction
// TODO: might be more efficient if ray tracing stopped after a short distance from ray origin
Raytrace.IntersectionInfo shadowInfo = geometry.IntersectRay(rayStart, rayDir, context);
if (shadowInfo == null || shadowInfo.rayFrac > ambientOcclusionProbeDist)
{
// This ray did not hit a nearby surface
rayEscapeCount++;
avgEscapedRayDir += rayDir;
}
}
// visualise direction of unobstructed space around surface point
//avgEscapedRayDir.Normalise();
//var v = new Vector(avgEscapedRayDir.x + 1, avgEscapedRayDir.y + 1, avgEscapedRayDir.z + 1);
//v *= 128;
//return Surface.PackRgb((byte)v.x, (byte)v.y, (byte)v.z);
//avgEscapedRayDir.Normalise();
//avgEscapedRayDir *= 255;
//return Surface.PackRgb((byte)avgEscapedRayDir.x, (byte)avgEscapedRayDir.y, (byte)avgEscapedRayDir.z);
return((double)rayEscapeCount / (double)ambientOcclusionQuality);
}
/// <summary>
/// Intersect a ray against this object.
/// </summary>
/// <param name="start">The start position of the ray, in object space.</param>
/// <param name="dir">The direction of the ray, in object space (not a unit vector).</param>
/// <returns>Information about the nearest intersection, or null if no intersection.</returns>
public IntersectionInfo IntersectRay(Vector start, Vector dir, RenderContext context)
{
Contract.Ensures(Contract.Result <IntersectionInfo>() == null || (Contract.Result <IntersectionInfo>().color & 0xff000000) == 0xff000000);
// trace ray through underlying geometry
IntersectionInfo info = geometry.IntersectRay(start, dir, context);
// if we are disabled, pass-through the ray intersection
if (!Enabled)
{
return(info);
}
// did ray not hit any geometry?
if (info == null)
{
return(null);
}
// shade the surface point
Vector surfaceNormal = info.normal;
Vector newRayStart = info.pos + surfaceNormal * raySurfaceOffset;
Vector newRayDir = RandomRayInHemisphere(surfaceNormal, context.RNG);
newRayDir.Normalise(); // only needed for calling BRDF function
// Fire off ray to check for another surface in the chosen direction
Raytrace.IntersectionInfo newRayInfo = geometry.IntersectRay(newRayStart, newRayDir, context);
// Did this ray did hit another surface?
Color incomingLight = Color.Black; // TODO: use background color from Renderer
if (newRayInfo != null)
{
incomingLight = new Color(newRayInfo.color);
}
// TODO: color conversions are probably very slow
Color surfaceEmission = new Color(info.color); // TODO: info.color might be shaded surface color! We want the raw material color here!
double reflectedLightFrac = BRDF(newRayDir, surfaceNormal /*, dir */);
Color outgoingLight = incomingLight * reflectedLightFrac + surfaceEmission;
// only normalise colour if R, G or B are greater than 1.0
if (outgoingLight.r > 1.0 || outgoingLight.g > 1.0 || outgoingLight.b > 1.0)
{
outgoingLight.Normalise();
}
Contract.Assert(0.0 <= outgoingLight.r && outgoingLight.r <= 1.0);
Contract.Assert(0.0 <= outgoingLight.g && outgoingLight.g <= 1.0);
Contract.Assert(0.0 <= outgoingLight.b && outgoingLight.b <= 1.0);
info.color = outgoingLight.ToARGB();
return(info);
}
// Returns index of triangle most frequently intersected by random rays along lightfield cell's beam
// Returns -1 if no triangle is intersected
private int BeamTriangleComplexIntersect(Coord4D lfCoord, RenderContext context)
{
var triCount = new Dictionary <int, short>();
for (int i = 0; i < 100; i++)
{
const double bias = +0.5;
Float4D randCoord = new Float4D(
lfCoord.Item1 + random.NextDouble() + bias,
lfCoord.Item2 + random.NextDouble() + bias,
lfCoord.Item3 + random.NextDouble() + bias,
lfCoord.Item4 + random.NextDouble() + bias);
// switch to tracing the canonical ray associated with this lightfield entry, instead of the original ray (to avoid biasing values in lightfield)
Vector cellRayStart;
Vector cellRayDir;
lightFieldCache.Float4DToRay(randCoord, out cellRayStart, out cellRayDir);
// TODO: once the light field cache 'fills up', do we cease tracing rays? Prove/measure this!
// trace a primary ray against all triangles in scene
// TODO: trace multiple rays to find the triangle with largest cross-section in the beam corresponding to this lightfield cell?
// This may also avoid incorrectly storing 'missing triangle' value when primary ray misses because there are no triangles along central axis of cell's beam.
IntersectionInfo intersection = geometry_subdivided.IntersectRay(cellRayStart, cellRayDir, context);
if (null != intersection)
{
var triIndex = intersection.triIndex;
Contract.Assert(triIndex >= 0);
if (triCount.ContainsKey(triIndex))
{
triCount[triIndex]++;
}
else
{
triCount[triIndex] = 1;
}
}
}
if (triCount.Count == 0)
{
return(-1);
}
else
{
// find tri index that occurs most often
var maxCount = triCount.Max(x => x.Value);
return(triCount.First(x => x.Value == maxCount).Key);
}
}
/// <summary>
/// Clip a line segment against this axis-aligned box.
/// Any portion of the line segment within this box is returned.
/// Otherwise false is returned.
/// </summary>
/// <param name="start">The start position of the line segment, in object space.</param>
/// <param name="end">The end position of the line segment, in object space.</param>
/// <returns>False if line segment entirely outside of box;
/// True if some portion of line segment is inside box</returns>
public bool ClipLineSegment(ref Vector start, ref Vector end)
{
bool startInside = ContainsPoint(start);
bool endInside = ContainsPoint(end);
if (startInside && endInside)
{
// Line segment is entirely inside this box.
return(true);
}
IntersectionInfo intersection = IntersectLineSegment(start, end);
if (intersection == null)
{
// Line segment does not intersect box, so entirely outside of box.
Contract.Assert(!startInside && !endInside, "Start and end must be outside box");
return(false);
}
// Line segment intersects box.
if (startInside)
{
// Only end is outside of box, so clipped line is now entirely within the box.
end = intersection.pos;
return(true);
}
// Start is outside box, so clip to surface of box.
Vector originalStart = start;
start = intersection.pos;
// Is end outside of box?
if (!endInside)
{
// End is outside of box, and original start was outside of box,
// so original line segment must intersect box at two points.
intersection = IntersectLineSegment(end, originalStart);
Contract.Assume(intersection != null, "Intersection must exist");
end = intersection.pos;
}
return(true);
}
/// <summary>
/// Intersect a ray against this object.
/// </summary>
/// <param name="start">The start position of the ray, in object space.</param>
/// <param name="dir">The direction of the ray, in object space (not a unit vector).</param>
/// <returns>Information about the nearest intersection, or null if no intersection.</returns>
/// <remarks>Thread safe</remarks>
public IntersectionInfo IntersectRay(Vector start, Vector dir, RenderContext context)
{
// trace ray through underlying geometry
IntersectionInfo info = geometry.IntersectRay(start, dir, context);
// if AO is disabled, pass-through the ray intersection
if (!Enabled)
{
return(info);
}
// did ray not hit any geometry?
if (info == null)
{
return(null);
}
if (ambientOcclusionCache == null)
{
// Create ambient occlusion cache, and optionally load cache data from disk
// Extract the name of the model from the 3DS file name.
// TODO: this is missing most/all of the time!
//var modelFileName = model.GetFileName();
//Contract.Assert(modelFileName != null && modelFileName.Length > 0);
//var modelName = RemoveFileExtension(modelFileName);
// TODO: power-of-two size/resolution might make 3D array indexing quicker
ambientOcclusionCache = new AmbientOcclusion(resolution, instanceKey, cachePath);
}
// Should the AO cache be enabled, or pass-through?
ambientOcclusionCache.EnableCache = EnableAoCache;
// shade surface point based on nearby geometry blocking ambient light from reaching surface
var lightIntensityByte = ambientOcclusionCache.CacheAmbientOcclusion(info, geometry, context);
info.color = Color.ModulatePackedColor(info.color, lightIntensityByte);
return(info);
}
/// <summary>
/// Intersect a ray against this object.
/// </summary>
/// <param name="start">The start position of the ray, in object space.</param>
/// <param name="dir">The direction of the ray, in object space (not a unit vector).</param>
/// <returns>Information about the nearest intersection, or null if no intersection.</returns>
public IntersectionInfo IntersectRay(Vector start, Vector dir, RenderContext context)
{
// Project the start and direction vectors onto the plane normal.
// Note that all distances are in multiples of the normal, NOT in space units!
double startDist = start.DotProduct(_normal);
double dirDist = dir.DotProduct(_normal);
// Make the plane one-sided.
if (dirDist >= 0.0)
{
return(null);
}
double rayFrac = _originDist - startDist;
if (rayFrac <= 0.0 /* epsilon */)
{
rayFrac /= dirDist;
IntersectionInfo info = new IntersectionInfo();
info.pos = start + dir * rayFrac;
info.normal = _normal;
info.rayFrac = rayFrac;
info.color = color;
// TODO: better parameterisation of the surface
// info.u = info.pos.x;
// info.v = info.pos.z;
Assert.IsTrue(info.rayFrac >= 0.0, "Ray fraction is negative");
return(info);
}
else
{
return(null);
}
}
/// <summary>
/// Calculates soft shadows at a point on a surface.
/// Multithread safe?
/// </summary>
/// <param name="surfacePos">Position of surface point to be shadowed</param>
/// <param name="surfaceNormal">Normal to surface at surface point</param>
/// <param name="geometry">The geometry to be raytraced (both shadow caster and shadow receiver)</param>
/// <returns>Fraction of light reaching the surface point (between 0 and 1): 0 = surface point fully shadowed; 1 = surface point not shadowed at all</returns>
private double TraceRaysForSoftShadows(Vector surfacePos, Vector surfaceNormal, IRayIntersectable geometry, RenderContext context)
{
int rayEscapeCount = 0;
for (int i = 0; i < softShadowQuality; i++)
{
// Check for shadow. Calculate direction and distance from light to surface point.
Vector dirLightToSurface;
Vector shadowRayStart;
Vector shadowRayEnd = surfacePos + surfaceNormal * shadowProbeOffset;
if (scene.pointLighting)
{
// generate points on the surface of a unit sphere (representing the light source)
var lightSource = scene.positionalLightPos_Model + areaLightOffsets[i];
dirLightToSurface = shadowRayEnd - lightSource;
shadowRayStart = lightSource;
}
else
{
// Directional lighting.
// TODO: soft shadows might make no sense for a directional light!
dirLightToSurface = scene.directionalLightDir_Model;
shadowRayStart = shadowRayEnd + dirLightToSurface * 1000.0 + areaLightOffsets[i];
}
// Fire off shadow ray through underlying geometry
IntersectionInfo shadowInfo = geometry.IntersectRay(shadowRayStart, dirLightToSurface, context);
// Did the shadow ray hit an occluder before reaching the light?
if (shadowInfo == null || shadowInfo.rayFrac > 1.0)
{
// No, so this light ray reaches the surface point
rayEscapeCount++;
}
}
return((double)rayEscapeCount / (double)softShadowQuality);
}
/// <summary>
/// Intersect a ray against this object.
/// </summary>
/// <param name="start">The start position of the ray, in object space.</param>
/// <param name="dir">The direction of the ray, in object space (not a unit vector).</param>
/// <returns>Information about the nearest intersection, or null if no intersection.</returns>
public IntersectionInfo IntersectRay(Vector start, Vector dir, RenderContext context)
{
// trace ray through underlying geometry
IntersectionInfo info = geometry.IntersectRay(start, dir, context);
// if shading is disabled, pass-through the ray intersection
if (!Enabled)
{
return(info);
}
// did ray not hit any geometry?
if (info == null)
{
return(null);
}
// shade the surface point based on angle of lighting
//double intensity = CalcLightingIntensity(info.pos, info.normal); // in object space
// TODO: All lighting calcs are broken for raytracing.
Vector pos_View = instance.TransformPosToView(info.pos);
Vector normal_View = instance.TransformDirection(info.normal);
double intensity = CalcLightingIntensity(pos_View, normal_View);
byte lightIntensityByte = 255; // TODO: change this to a double in range [0, 1] so that conversion to byte occurs only once?
lightIntensityByte = (byte)(lightIntensityByte * intensity);
//else
//{
// return Surface.PackRgb(lightIntensityByte, lightIntensityByte, lightIntensityByte);
//}
//color = Surface.ColorFromArgb(0, intensityByte, intensityByte, intensityByte);
info.color = Color.ModulatePackedColor(info.color, lightIntensityByte);
return(info);
}
private uint CalcColorForCoord(Coord4D lfCoord, RenderContext context)
{
// Index into light field cache using 4D spherical coordinates
uint lfCacheEntry = lightFieldCache.ReadCache(lfCoord.Item1, lfCoord.Item2, lfCoord.Item3, lfCoord.Item4);
if (lfCacheEntry != lightFieldCache.EmptyCacheEntry)
{
// lightfield stores colors, and we found a color entry to return
return(lfCacheEntry);
}
// switch to tracing the ray associated with this lightfield entry, instead of the original ray (to avoid biasing values in lightfield)
Vector rayStart;
Vector rayDir;
lightFieldCache.Coord4DToRay(lfCoord, out rayStart, out rayDir);
// TODO: once the light field cache 'fills up', do we cease tracing rays? Prove/measure this!
// we did not find a color in the light field corresponding to this ray, so trace this ray against the geometry
// TODO: this line is the major performance bottleneck!
IntersectionInfo info = geometry.IntersectRay(rayStart, rayDir, context);
if (info == null)
{
// ray did not hit the geometry, so cache background color into the 4D light field
lightFieldCache.WriteCache(lfCoord.Item1, lfCoord.Item2, lfCoord.Item3, lfCoord.Item4, backgroundColor);
return(backgroundColor);
}
// TODO: this is where lots of other AO, shadow code etc used to execute
// cache ray colors in a 4D light field?
lightFieldCache.WriteCache(lfCoord.Item1, lfCoord.Item2, lfCoord.Item3, lfCoord.Item4, info.color);
return(info.color);
}
/// <summary>
/// Intersect a ray against this object.
/// </summary>
/// <param name="start">The start position of the ray, in object space.</param>
/// <param name="dir">The direction of the ray, in object space (not a unit vector).</param>
/// <returns>Information about the nearest intersection, or null if no intersection.</returns>
public IntersectionInfo IntersectRay(Vector start, Vector dir, RenderContext context)
{
// if lightfield is disabled, pass-through the ray intersection
if (!Enabled)
{
return(geometry.IntersectRay(start, dir, context));
}
// lazily create the lightfield cache
if (lightFieldCache == null)
{
lightFieldCache = new LightField4D <ushort>(resolution, instanceKey, default(ushort), default(ushort) + 1, cachePath);
}
// cache triangle indices in a 4D light field
Coord4D lfCoord = null;
Vector rayStart = start;
Vector rayDir = dir;
// Convert ray to 4D spherical coordinates
// TODO: do we need locking to ensure another thread does not overwrite this lightfield cache entry?
lfCoord = lightFieldCache.RayToCoord4D(ref rayStart, ref rayDir);
if (lfCoord == null)
{
return(null);
}
// TODO: debugging. Very slow! Also broken as of Aug 2016.
//Vector tmpStart;
//Vector tmpDir;
//lightFieldCache.Coord4DToRay(lfCoord, out tmpStart, out tmpDir);
//var tmpCoord = lightFieldCache.RayToCoord4D(ref tmpStart, ref tmpDir);
//Contract.Assert(tmpCoord.Equals(lfCoord));
// Index into light field cache using 4D spherical coordinates
ushort lfCacheEntry = lightFieldCache.ReadCache(lfCoord.Item1, lfCoord.Item2, lfCoord.Item3, lfCoord.Item4);
if (lfCacheEntry == lightFieldCache.EmptyCacheEntryReplacement)
{
// cache entry indicates 'missing triangle', so nothing to intersect against
return(null);
}
// if lightfield cache entry is empty, populate it with a triangle from the cell's beam
int triIndex;
if (lightFieldCache.EmptyCacheEntry == lfCacheEntry)
{
// lightfield does not yet contain a triangle entry to intersect against
// TODO: once the light field cache 'fills up', do we cease tracing rays? Prove/measure this!
// Intersect random rays along beam of lightfield cell, against all triangles
// TODO: this *should* improve quality, but seems to decrease it, and adds a little randomness to the regression tests
//triIndex = BeamTriangleComplexIntersect(lfCoord, context);
// Intersect central axis of lightfield cell against all triangles
triIndex = BeamTriangleSimpleIntersect(lfCoord, context);
if (triIndex == -1)
{
// Cache 'missing triangle' value into the light field cache
lightFieldCache.WriteCache(lfCoord.Item1, lfCoord.Item2, lfCoord.Item3, lfCoord.Item4, lightFieldCache.EmptyCacheEntryReplacement);
return(null);
}
else
{
// Take triangle that we intersected, and store its index into the light field cache
// TODO: triIndex could overflow a ushort and wrap around to an incorrect triangle index!
lfCacheEntry = (ushort)(triIndex + 2); // account for empty cache value and replacement cache value (i.e. avoid storing 0 or 1 into lightfield)
lightFieldCache.WriteCache(lfCoord.Item1, lfCoord.Item2, lfCoord.Item3, lfCoord.Item4, lfCacheEntry);
}
}
Contract.Assert(lightFieldCache.EmptyCacheEntry != lfCacheEntry);
// lightfield contains a triangle entry to intersect against
// store triangle indices in light field, and raytrace the triangle that we get from the lightfield
// TODO: Store index of bucket of triangles into lightfield? Tradeoff between small buckets and many buckets. Optimise for 8-bit or 16-bit bucket indices?
// Intersect primary ray against closest/likely/best triangle (from lightfield cache)
triIndex = (int)lfCacheEntry - 2; // discount empty and replacement cache values
// TODO: Contracts analyser says assert unproven
Contract.Assert(triIndex >= 0);
var tri = geometry_simple[triIndex] as Raytrace.Triangle;
IntersectionInfo intersection = tri.IntersectRay(rayStart, rayDir, context); // intersect ray against triangle
// intersect ray against plane of triangle, to avoid holes by covering full extent of lightfield cell. Creates spatial tearing around triangle silhouettes.
//info = tri.Plane.IntersectRay(rayStart, rayDir);
//info.color = tri.Color; // all planes are white, so use color of triangle
if (intersection == null)
{
// Intersect ray against triangles 'near' to the triangle from the lightfield (i.e. in the same subdivision node).
// This is slower than intersecting the single triangle from the lightfield, but much faster than intersecting the entire subdivision structure.
// TODO: need to walk the subdivision tree to find triangles in nearby tree nodes
intersection = geometry_subdivided.IntersectRayWithLeafNode(rayStart, rayDir, tri, context);
#if VISUALISATION
if (intersection != null)
{
return new IntersectionInfo {
color = 0x000000FF, normal = new Vector(0, 1, 0)
}
}
; // visualise hitting nearby triangle (blue)
#endif
}
if (intersection == null)
{
// Intersect ray against all triangles in the geometry.
// TODO: this is much slower than intersecting the single triangle from the lightfield, or the triangles in the same node.
// Performance will be reasonable if not many pixels reach this code path.
intersection = geometry_subdivided.IntersectRay(rayStart, rayDir, context);
#if VISUALISATION
if (intersection != null)
{
return new IntersectionInfo {
color = 0x00FF0000, normal = new Vector(0, 1, 0)
}
}
; // visualise hitting triangle in distant node (red)
#endif
}
//if (info == null)
//{
// // intersect ray against plane of triangle, to avoid holes by covering full extent of lightfield cell
// // TODO: this creates spatial tearing around triangle silhouettes, as all background pixels in this cell are covered by this plane.
// info = tri.Plane.IntersectRay(rayStart, rayDir);
// if (info != null)
// info.color = tri.Color; // all planes are white, so use color of triangle
//}
#if VISUALISATION
if (intersection == null)
{
return new IntersectionInfo {
color = 0x0000FF00, normal = new Vector(0, 1, 0)
}
}
; // visualise missing nearby triangles (green)
#endif
return(intersection);
}
/// <summary>
/// Intersect a ray against this object.
/// </summary>
/// <param name="start">The start position of the ray, in object space.</param>
/// <param name="dir">The direction of the ray, in object space (not a unit vector).</param>
/// <returns>Information about the nearest intersection, or null if no intersection.</returns>
public IntersectionInfo IntersectRay(Vector start, Vector dir, RenderContext context)
{
// TODO: optimise ray-sphere intersection code
// Make dir a unit vector.
// TODO: not strictly neccessary, but it makes the quadratic equation a bit simpler.
// TODO: make this function faster by removing the normalise, and accounting for sphereToStartProjDir
// being scaled up by the length of dir.
dir.Normalise();
// Solve quadratic equation to determine number of intersection points between (infinite) line and sphere: 0, 1 or 2 intersections
Vector sphereToStart = start - center; // o - c
double sphereToStartProjDir = sphereToStart.DotProduct(dir); // l.(o - c)
// Is the entire sphere behind the start of the ray?
if (sphereToStartProjDir > radius)
{
return(null);
}
double sphereToStartDistSqr = sphereToStart.LengthSqr; // |o - c|^2
// TODO: ignore rays starting inside the sphere?
// Is any part of the sphere behind the start of the ray?
// if(sphereToStartProjDir > -radius)
// return null;
// Is the sphere surrounding the ray start? TODO: is this ever true after the previous check?
// if(sphereToStartDistSqr < radiusSqr)
// return null;
double termUnderSqrRoot = sphereToStartProjDir * sphereToStartProjDir - sphereToStartDistSqr + radiusSqr; // (l.(o - c))^2 - |o - c|^2 + r^2
if (termUnderSqrRoot < epsilon) // use epsilon to avoid unstable pixels flickering between one root and zero roots
// (infinite) line does not intersect sphere
{
return(null);
}
double positiveSqrRoot = Math.Sqrt(termUnderSqrRoot);
double intersectRayFrac1 = -sphereToStartProjDir - positiveSqrRoot; // distance along line from ray-start to first intersection
double intersectRayFrac2 = -sphereToStartProjDir + positiveSqrRoot; // distance along line from ray-start to second intersection (might be same as first intersection)
double rayFrac = (intersectRayFrac1 >= 0 ? intersectRayFrac1 : intersectRayFrac2);
if (rayFrac < 0)
{
// (infinite) line intersects sphere, but ray does not
return(null);
}
// Determine details of nearest intersection point
// TODO: rearchitect to avoid calculating intersection position and normal unless this is the first object hit
IntersectionInfo info = new IntersectionInfo();
info.rayFrac = rayFrac;
info.pos = start + dir * rayFrac;
info.normal = info.pos - center;
info.normal.Normalise();
info.color = color;
// TODO: this is for debugging spherical angles!
/*
* // work out spherical angles of intersection point
* var sphereToHitPt = info.pos - center;
* var horizAngle = Math.Atan2(sphereToHitPt.x, sphereToHitPt.z); // longitude of point on sphere, -π ≤ θ ≤ π
* var vertAngle = Math.Asin(sphereToHitPt.y / radius); // latitude of point on sphere, -π/2 ≤ θ ≤ π/2
*
* //var visualNorm = horizAngle / Math.PI / 2.0 + 0.5; // [0, 1]
* var visualNorm = vertAngle / Math.PI + 0.5; // [0, 1]
* //byte visualNormByte = (byte)(visualNorm * 255); // [0, 255]
* var visualNormInt = (int)(visualNorm * 255); // [0, 255]
* info.color = (uint)(visualNormInt << 8);
* //info.color = (uint)((visualNormByte << 16) + (visualNormByte << 8) + visualNormByte);
*/
return(info);
}
//public void CalcAllAmbientOcclusion()
//{
// // TODO: write brute force algorithm: for every cell in 3D cube, find intersecting triangles and calc AO for these? Or just find nearest triangle to each cell center?
//}
/// <summary>
/// Calculates and caches ambient occlusion at a point on a surface.
/// Multithread safe.
/// </summary>
/// <param name="surface">Information about surface point</param>
/// <param name="geometry">The geometry to be raytraced (both occlusion caster and occlusion receiver)</param>
/// <param name="random">Random number generator to use. Set to <value>NULL</value> to use the default random number generator</param>
/// <returns>Fraction of non-occlusion at surface point (between 1 and 255): 1 = surface point fully occluded by neighbour surfaces; 255 = surface point not occluded at all</returns>
public T CacheAmbientOcclusion(IntersectionInfo surface, Raytrace.IRayIntersectable geometry, RenderContext context)
{
Contract.Requires(surface != null);
// TODO: Sometimes a surface point coordinate is very slightly outside the unit cube (i.e. Z coordinate of 0.50000000001)
const double maxExtent = 0.5; // TODO: extent seems too large on Couch model...
const double scale = 0.5 / maxExtent;
// So we clamp coordinates to the unit cube
surface.pos.x = Math.Min(Math.Max(-0.5, surface.pos.x), 0.5);
surface.pos.y = Math.Min(Math.Max(-0.5, surface.pos.y), 0.5);
surface.pos.z = Math.Min(Math.Max(-0.5, surface.pos.z), 0.5);
/*
* Assert.IsTrue(-maxExtent <= surface.pos.x && surface.pos.x <= maxExtent, "Surface point is outside unit cube");
* Assert.IsTrue(-maxExtent <= surface.pos.y && surface.pos.y <= maxExtent, "Surface point is outside unit cube");
* Assert.IsTrue(-maxExtent <= surface.pos.z && surface.pos.z <= maxExtent, "Surface point is outside unit cube");
*/
var cacheIndex = (int)((surface.pos.x * scale + 0.5) * (cacheSize - 1)) * cacheSize * cacheSize +
(int)((surface.pos.y * scale + 0.5) * (cacheSize - 1)) * cacheSize +
(int)((surface.pos.z * scale + 0.5) * (cacheSize - 1));
// fetch cache entry, but if missing then calc AO factor
// TODO: probably not multithread safe!
// TODO: tri-linearly interpolate AO factor from eight neighbouring cache entries for smoother results!
// Cheap thread lock - prevent other threads recalculating this value, while it is calculated by this thread
// TODO: cannot be used with byte values, but could be used with ints
//if(0 == Interlocked.CompareExchange<byte>(ref cacheData[cacheIndex], (byte)1, (byte)0))
if (!EnableCache)
{
// calc shading intensity based on percentage AO shadowing
double unoccludedFactor = CalcAmbientOcclusion(surface, geometry, context);
// scale to range [1, 255]. We avoid zero as this is a sentinel value indicating empty cache entry.
return((T)(unoccludedFactor * 254 + 1));
}
// Double-check locking pattern
// TODO: rare IndexOutOfRangeException here
T lightByte = cacheData[cacheIndex];
if (EmptyCacheEntry == lightByte)
{
lock (calcLock)
{
// another thread may have got the lock first, and already calculated this value
if (EmptyCacheEntry == cacheData[cacheIndex])
{
// calc shading intensity based on percentage AO shadowing
double unoccludedFactor = CalcAmbientOcclusion(surface, geometry, context);
// scale to range [1, 255]. We avoid zero as this is a sentinel value indicating empty cache entry.
lightByte = (T)(unoccludedFactor * 254 + 1);
cacheData[cacheIndex] = lightByte;
// Time to persist cache data to file in isolated storage?
numCalcsUntilNextPersist--;
if (numCalcsUntilNextPersist <= 0)
{
// TODO: lock may be held for long time!
SaveCacheToDisk(cacheFilePath, cacheData);
numCalcsUntilNextPersist = numCalcsBetweenPersists;
}
}
}
}
return(lightByte);
}
