public static void ClosestPointOnPolygon(RenderVertex3D[] rgv, Vertex2D pvin, bool fClosed, out Vertex2D pvOut, out int piSeg)
{
var count = rgv.Length;
var minDist = Constants.FloatMax;
piSeg = -1; // in case we are not next to the line
pvOut = new Vertex2D();
var loopCount = count;
if (!fClosed)
{
--loopCount; // Don"t check segment running from the end point to the beginning point
}
// Go through line segment, calculate distance from point to the line
// then pick the shortest distance
for (var i = 0; i < loopCount; ++i)
{
var p2 = i < count - 1 ? i + 1 : 0;
var rgvi = new RenderVertex3D();
rgvi.Set(rgv[i].X, rgv[i].Y, rgv[i].Z);
var rgvp2 = new RenderVertex3D();
rgvp2.Set(rgv[p2].X, rgv[p2].Y, rgv[p2].Z);
var a = rgvi.Y - rgvp2.Y;
var b = rgvp2.X - rgvi.X;
var c = -(a * rgvi.X + b * rgvi.Y);
var dist = MathF.Abs(a * pvin.X + b * pvin.Y + c) / MathF.Sqrt(a * a + b * b);
if (dist < minDist)
{
// Assuming we got a segment that we are closet to, calculate the intersection
// of the line with the perpendicular line projected from the point,
// to find the closest point on the line
var d = -b;
var f = -(d * pvin.X + a * pvin.Y);
var det = a * a - b * d;
var invDet = det != 0.0f ? 1.0f / det : 0.0f;
var intersectX = (b * f - a * c) * invDet;
var intersectY = (c * d - a * f) * invDet;
// If the intersect point lies on the polygon segment
// (not out in space), then make this the closest known point
if (intersectX >= MathF.Min(rgvi.X, rgvp2.X) - 0.1 &&
intersectX <= MathF.Max(rgvi.X, rgvp2.X) + 0.1 &&
intersectY >= MathF.Min(rgvi.Y, rgvp2.Y) - 0.1 &&
intersectY <= MathF.Max(rgvi.Y, rgvp2.Y) + 0.1)
{
minDist = dist;
var seg = i;
pvOut.X = intersectX;
pvOut.Y = intersectY;
piSeg = seg;
}
}
}
}
public RampVertex GetRampVertex(float tableHeight, float accuracy, bool incWidth)
{
var result = new RampVertex();
// vvertex are the 2D vertices forming the central curve of the ramp as seen from above
var vertex = GetCentralCurve(accuracy);
var numVertices = vertex.Length;
result.VertexCount = numVertices;
result.PointHeights = new float[numVertices];
result.Cross = new bool[numVertices];
result.PointRatios = new float[numVertices];
result.MiddlePoints = new Vertex2D[numVertices];
result.RgvLocal = new Vertex2D[_data.Type != RampType.RampTypeFlat ? (numVertices + 1) * 2 : numVertices * 2];
// Compute an approximation to the length of the central curve
// by adding up the lengths of the line segments.
var totalLength = 0f;
var bottomHeight = _data.HeightBottom + tableHeight;
var topHeight = _data.HeightTop + tableHeight;
for (var i = 0; i < numVertices - 1; i++)
{
var v1 = vertex[i];
var v2 = vertex[i + 1];
var dx = v1.X - v2.X;
var dy = v1.Y - v2.Y;
var length = MathF.Sqrt(dx * dx + dy * dy);
totalLength += length;
}
var currentLength = 0f;
for (var i = 0; i < numVertices; i++)
{
// clamp next and prev as ramps do not loop
var prev = vertex[i > 0 ? i - 1 : i];
var next = vertex[i < numVertices - 1 ? i + 1 : i];
var middle = vertex[i];
result.Cross[i] = middle.IsControlPoint;
var normal = new Vertex2D();
// Get normal at this point
// Notice that these values equal the ones in the line
// equation and could probably be substituted by them.
var v1Normal = new Vertex2D(prev.Y - middle.Y, middle.X - prev.X); // vector vmiddle-vprev rotated RIGHT
var v2Normal = new Vertex2D(middle.Y - next.Y, next.X - middle.X); // vector vnext-vmiddle rotated RIGHT
// special handling for beginning and end of the ramp, as ramps do not loop
if (i == numVertices - 1)
{
v1Normal.Normalize();
normal = v1Normal;
}
else if (i == 0)
{
v2Normal.Normalize();
normal = v2Normal;
}
else
{
v1Normal.Normalize();
v2Normal.Normalize();
if (MathF.Abs(v1Normal.X - v2Normal.X) < 0.0001 && MathF.Abs(v1Normal.Y - v2Normal.Y) < 0.0001)
{
// Two parallel segments
normal = v1Normal;
}
else
{
// Find intersection of the two edges meeting this points, but
// shift those lines outwards along their normals
// First line
var a = prev.Y - middle.Y;
var b = middle.X - prev.X;
// Shift line along the normal
var c = -(a * (prev.X - v1Normal.X) + b * (prev.Y - v1Normal.Y));
// Second line
var d = next.Y - middle.Y;
var e = middle.X - next.X;
// Shift line along the normal
var f = -(d * (next.X - v2Normal.X) + e * (next.Y - v2Normal.Y));
var det = a * e - b * d;
var invDet = det != 0.0 ? 1.0f / det : 0.0f;
var intersectX = (b * f - e * c) * invDet;
var intersectY = (c * d - a * f) * invDet;
normal.X = middle.X - intersectX;
normal.Y = middle.Y - intersectY;
}
}
// Update current length along the ramp.
var dx = prev.X - middle.X;
var dy = prev.Y - middle.Y;
var length = MathF.Sqrt(dx * dx + dy * dy);
currentLength += length;
var percentage = currentLength / totalLength;
var currentWidth = percentage * (_data.WidthTop - _data.WidthBottom) + _data.WidthBottom;
result.PointHeights[i] = middle.Z + percentage * (topHeight - bottomHeight) + bottomHeight;
AssignHeightToControlPoint(new Vertex2D(vertex[i].X, vertex[i].Y), middle.Z + percentage * (topHeight - bottomHeight) + bottomHeight);
result.PointRatios[i] = 1.0f - percentage;
// only change the width if we want to create vertices for rendering or for the editor
// the collision engine uses flat type ramps
if (IsHabitrail() && _data.Type != RampType.RampType1Wire)
{
currentWidth = _data.WireDistanceX;
if (incWidth)
{
currentWidth += 20.0f;
}
}
else if (_data.Type == RampType.RampType1Wire)
{
currentWidth = _data.WireDiameter;
}
result.MiddlePoints[i] = new Vertex2D(middle.X, middle.Y) + normal;
result.RgvLocal[i] = new Vertex2D(middle.X, middle.Y) + currentWidth * 0.5f * normal;
result.RgvLocal[numVertices * 2 - i - 1] = new Vertex2D(middle.X, middle.Y) - currentWidth * 0.5f * normal;
}
return(result);
}
public bool IsZero()
{
return(MathF.Abs(X) < Constants.FloatMin && MathF.Abs(Y) < Constants.FloatMin &&
MathF.Abs(Z) < Constants.FloatMin);
}
