Filling the space between bezier curves with a texture,

Question

I want to dynamically draw 2D road segments in Unity with scripts. Each segment is defined by 4 points and the required control points to draw bezier curves. This means a segments outer shape consists of 2 "ends" wich are just simple lines, and 2 bezier curves.

I am using this https://github.com/dbrizov/NaughtyBezierCurves to create the bezier curves. This results into an outer shape of a segment like this:

outer shape

Creating the outer shape of a segment is pretty simple. Now I want to fill the segment with a texture. I dont know how I can create planes or a mesh with the same shape as the outer shape of the segment. This is what I want to achive: alt text I first thought about going along the bezier curves and creating slim splanes all along the curve, but this would lead to overlapping or gaps between them. Plus, I dont know how to orient the planes towards the other curve.

Maybe someone has a simple solution how I can add a texture to the road with a script.

,

Answer 1

alt text

Discretize your curves into two point lists. Build the mesh like this (Not tested but should not be too wrong):

 // Discretize the curves
 // You have verticesOnCurve1[n] and verticesOnCurve2[n]
 // float width is your road's width
 
 //// Vertices ////
 List<Vector3> vertexBuffer = new List<Vector3>();
 for (int i = 0; i < n; i++) {
     vertexBuffer.Add(verticesOnCurve1[i]); // Top points
 }
 for (int i = 0; i < n; i++) {
     vertexBuffer.Add(verticesOnCurve2[i]); // Bottom points
 }
 
 //// Indices ////
 List<int> indexBuffer = new List<int>();
 for (int i = 0; i < n - 1; i++) {
     indexBuffer.Add(i);
     indexBuffer.Add(i + 1);
     indexBuffer.Add(n + i);
     indexBuffer.Add(n + i);
     indexBuffer.Add(i + 1);
     indexBuffer.Add(n + i + 1);
 }
 
 //// UVs ////
 List<float> pointMileages = new List<float>(); // Mileages are calculated from the top curve
 pointMileages.Add(0); // Starting point
 for (int i = 1; i < n; i++) {
     var distance = (verticesOnCurve1[i] - verticesOnCurve1[i - 1]).magnitude;
     pointMileages.Add(pointMileages[i - 1] + distance); // Other points
 }
 List<Vector2> uvs = new List<Vector2>();
 for (int i = 0; i < n; i++) {
     uvs.Add(new Vector2(pointMileages[i] / width, 0)); // Top points
 }
 for (int i = 0; i < n; i++) {
     uvs.Add(new Vector2(pointMileages[i] / width, 1)); // Bottom points
 }

Filling the space between bezier curves with a texture,

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