Created
July 25, 2022 09:16
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Bezier visualization script for grass blade generation
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using System.Collections; | |
using System.Collections.Generic; | |
using UnityEngine; | |
[ExecuteAlways] | |
public class BezierTest : MonoBehaviour { | |
public int numOfPoints; | |
public float height = 1; | |
public float forwardRotation = 0; | |
public float curvature = 0; | |
private Vector3 normal = Vector3.up; | |
private Vector3 tangent = Vector3.right; | |
private Vector3[] points; | |
private Vector3[] tangents; | |
private Vector3 pointA, pointB, handle; | |
private void OnEnable() { | |
normal = transform.up; | |
tangent = transform.right; | |
} | |
private void Update() { | |
Vector3 bitangent = Vector3.Cross(normal, tangent).normalized; | |
pointA = Vector3.zero; | |
pointB = Vector3.zero + normal * height + forwardRotation * height * bitangent; | |
handle = (pointA + pointB) * 0.5f - Vector3.Cross(pointB - pointA, tangent).normalized * curvature * forwardRotation * height; | |
points = new Vector3[numOfPoints]; | |
tangents = new Vector3[numOfPoints]; | |
for (int i = 0; i < numOfPoints; i++) { | |
float t = (float)i / numOfPoints; | |
points[i] = GetBezierPoint(pointA, pointB, handle, t); | |
tangents[i] = GetBezierPointTangent(pointA, pointB, handle, t); | |
} | |
} | |
private Vector3 GetBezierPoint(Vector3 pointA, Vector3 pointB, Vector3 handle, float t) { | |
return (1 - t) * ((1 - t) * pointA + t * handle) + t * ((1 - t) * handle + t * pointB); | |
} | |
private Vector3 GetBezierPointTangent(Vector3 pointA, Vector3 pointB, Vector3 handle, float t) { | |
return (2 * t * (pointA - 2 * handle + pointB) + 2 * (handle - pointA)).normalized; | |
} | |
private void OnDrawGizmos() { | |
Gizmos.color = Color.green; | |
Vector3 worldPointA = transform.TransformPoint(pointA); | |
Vector3 worldPointB = transform.TransformPoint(pointB); | |
Vector3 worldHandle = transform.TransformPoint(handle); | |
Gizmos.DrawSphere(worldPointA, 0.1f); | |
Gizmos.DrawSphere(worldPointB, 0.1f); | |
Gizmos.DrawSphere(worldHandle, 0.15f); | |
Gizmos.DrawLine(worldPointA, worldPointB); | |
Gizmos.DrawLine(worldHandle, (worldPointA + worldPointB) * 0.5f); | |
for (int i = 0; i < points.Length; i++) { | |
Gizmos.color = Color.yellow; | |
Vector3 point = transform.TransformPoint(points[i]); | |
Gizmos.DrawSphere(point, 0.05f); | |
if (i < points.Length - 1) { | |
Gizmos.DrawLine(point, transform.TransformPoint(points[i + 1])); | |
} else { | |
Gizmos.DrawLine(point, worldPointB); | |
} | |
Gizmos.color = Color.red; | |
Gizmos.DrawRay(point, transform.TransformDirection(tangents[i])); | |
Gizmos.color = Color.blue; | |
Vector3 normal = transform.TransformDirection(Quaternion.AngleAxis(90, tangent) * tangents[i]).normalized; | |
Gizmos.DrawRay(point, normal); | |
} | |
} | |
} |
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