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Update examples (add interpolation example 10).

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This commit is contained in:
wo80
2022-03-05 21:13:52 +01:00
parent ffbe041f7b
commit fd205fbb9c
11 changed files with 216 additions and 60 deletions
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src/Triangle/Tools/Interpolation.cs
+69 -42
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@@ -1,10 +1,54 @@
// -----------------------------------------------------------------------
// <copyright file="Interpolation.cs">
// Triangle Copyright (c) 1993, 1995, 1997, 1998, 2002, 2005 Jonathan Richard Shewchuk
// Triangle.NET code by Christian Woltering
// </copyright>
// -----------------------------------------------------------------------
namespace TriangleNet.Tools
{
using TriangleNet.Geometry;
public static class Interpolation
{
/// <summary>
/// Linear interpolation of a point.
/// </summary>
/// <param name="tri">The triangle containing the point <paramref name="p"/></param>
/// <param name="p">The point to interpolate.</param>
/// <param name="data">The vertex data (z values).</param>
/// <returns>The linear interpolation value.</returns>
/// <remarks>
/// IMPORTANT: this method assumes the mesh vertex ids correspond to the data array indices.
/// </remarks>
public static double InterpolatePoint(ITriangle tri, Point p, double[] data)
{
var org = tri.GetVertex(0);
var dest = tri.GetVertex(1);
var apex = tri.GetVertex(2);
double xdo = dest.x - org.x;
double ydo = dest.y - org.y;
double xao = apex.x - org.x;
double yao = apex.y - org.y;
double denominator = 0.5 / (xdo * yao - xao * ydo);
double dx = p.x - org.x;
double dy = p.y - org.y;
// To interpolate z value for the given point inserted, define a
// coordinate system with a xi-axis, directed from the triangle's
// origin to its destination, and an eta-axis, directed from its
// origin to its apex.
double xi = (yao * dx - xao * dy) * (2.0 * denominator);
double eta = (xdo * dy - ydo * dx) * (2.0 * denominator);
double orgz = data[org.id];
return orgz + xi * (data[dest.id] - orgz) + eta * (data[apex.id] - orgz);
}
#if USE_ATTRIBS
/// <summary>
/// Linear interpolation of vertex attributes.
@@ -17,35 +61,26 @@ namespace TriangleNet.Tools
/// </remarks>
public static void InterpolateAttributes(Vertex vertex, ITriangle triangle, int n)
{
Vertex org = triangle.GetVertex(0);
Vertex dest = triangle.GetVertex(1);
Vertex apex = triangle.GetVertex(2);
var org = triangle.GetVertex(0);
var dest = triangle.GetVertex(1);
var apex = triangle.GetVertex(2);
double xdo, ydo, xao, yao;
double denominator;
double dx, dy;
double xi, eta;
double xdo = dest.x - org.x;
double ydo = dest.y - org.y;
double xao = apex.x - org.x;
double yao = apex.y - org.y;
// Compute the circumcenter of the triangle.
xdo = dest.x - org.x;
ydo = dest.y - org.y;
xao = apex.x - org.x;
yao = apex.y - org.y;
double denominator = 0.5 / (xdo * yao - xao * ydo);
denominator = 0.5 / (xdo * yao - xao * ydo);
//dx = (yao * dodist - ydo * aodist) * denominator;
//dy = (xdo * aodist - xao * dodist) * denominator;
dx = vertex.x - org.x;
dy = vertex.y - org.y;
double dx = vertex.x - org.x;
double dy = vertex.y - org.y;
// To interpolate vertex attributes for the new vertex, define a
// coordinate system with a xi-axis directed from the triangle's
// origin to its destination, and an eta-axis, directed from its
// origin to its apex.
xi = (yao * dx - xao * dy) * (2.0 * denominator);
eta = (xdo * dy - ydo * dx) * (2.0 * denominator);
double xi = (yao * dx - xao * dy) * (2.0 * denominator);
double eta = (xdo * dy - ydo * dx) * (2.0 * denominator);
for (int i = 0; i < n; i++)
{
@@ -68,35 +103,27 @@ namespace TriangleNet.Tools
/// </remarks>
public static void InterpolateZ(Point p, ITriangle triangle)
{
Vertex org = triangle.GetVertex(0);
Vertex dest = triangle.GetVertex(1);
Vertex apex = triangle.GetVertex(2);
double xdo, ydo, xao, yao;
double denominator;
double dx, dy;
double xi, eta;
var org = triangle.GetVertex(0);
var dest = triangle.GetVertex(1);
var apex = triangle.GetVertex(2);
// Compute the circumcenter of the triangle.
xdo = dest.x - org.x;
ydo = dest.y - org.y;
xao = apex.x - org.x;
yao = apex.y - org.y;
double xdo = dest.x - org.x;
double ydo = dest.y - org.y;
double xao = apex.x - org.x;
double yao = apex.y - org.y;
denominator = 0.5 / (xdo * yao - xao * ydo);
double denominator = 0.5 / (xdo * yao - xao * ydo);
//dx = (yao * dodist - ydo * aodist) * denominator;
//dy = (xdo * aodist - xao * dodist) * denominator;
dx = p.x - org.x;
dy = p.y - org.y;
double dx = p.x - org.x;
double dy = p.y - org.y;
// To interpolate z value for the given point inserted, define a
// coordinate system with a xi-axis, directed from the triangle's
// origin to its destination, and an eta-axis, directed from its
// origin to its apex.
xi = (yao * dx - xao * dy) * (2.0 * denominator);
eta = (xdo * dy - ydo * dx) * (2.0 * denominator);
double xi = (yao * dx - xao * dy) * (2.0 * denominator);
double eta = (xdo * dy - ydo * dx) * (2.0 * denominator);
p.z = org.z + xi * (dest.z - org.z) + eta * (apex.z - org.z);
}