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273 行
6.8 KiB
273 行
6.8 KiB
using System.Collections;
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using System.Collections.Generic;
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using UnityEngine.Rendering;
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using UnityEngine;
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public class SkyboxHelper
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{
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public SkyboxHelper()
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{
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}
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const int NumFullSubdivisions = 3; // 3 subdivs == 2048 triangles
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const int NumHorizonSubdivisions = 2;
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public void CreateMesh()
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{
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Vector3[] vertData = new Vector3[8 * 3];
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for (int i = 0; i < 8 * 3; i++)
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{
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vertData[i] = octaVerts[i];
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}
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// Regular subdivisions
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for (int i = 0; i < NumFullSubdivisions; i++)
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{
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Vector3[] srcData = vertData.Clone() as Vector3[];
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List<Vector3> verts = new List<Vector3>();
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for (int k = 0; k < srcData.Length; k += 3)
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{
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Subdivide(verts, srcData[k], srcData[k + 1], srcData[k + 2]);
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}
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vertData = verts.ToArray();
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}
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// Horizon subdivisions
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float horizonLimit = 1.0f;
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for (int i = 0; i < NumHorizonSubdivisions; i++)
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{
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Vector3[] srcData = vertData.Clone() as Vector3[];
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List<Vector3> verts = new List<Vector3>();
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horizonLimit *= 0.5f; // First iteration limit to y < +-0.5, next one 0.25 etc.
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for (int k = 0; k < srcData.Length; k += 3)
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{
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float maxAbsY = Mathf.Max(Mathf.Abs(srcData[k].y), Mathf.Abs(srcData[k + 1].y), Mathf.Abs(srcData[k + 2].y));
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if (maxAbsY > horizonLimit)
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{
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// Pass through existing triangle
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verts.Add(srcData[k]);
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verts.Add(srcData[k + 1]);
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verts.Add(srcData[k + 2]);
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}
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else
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{
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SubdivideYOnly(verts, srcData[k], srcData[k + 1], srcData[k + 2]);
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}
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}
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vertData = verts.ToArray();
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}
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// Write out the mesh
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int vertexCount = vertData.Length;
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var triangles = new int[vertexCount];
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for (int i = 0; i < vertexCount; i++)
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{
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triangles[i] = i;
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}
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_mesh = new Mesh();
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_mesh.vertices = vertData;
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_mesh.triangles = triangles;
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}
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public UnityEngine.Mesh mesh
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{
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get { return _mesh; }
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}
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public void Draw(RenderLoop loop, Camera camera)
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{
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if (camera.clearFlags != CameraClearFlags.Skybox)
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{
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return;
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}
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Material mat = RenderSettings.skybox;
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if (mat == null)
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{
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return;
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}
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CommandBuffer cmd = new CommandBuffer();
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cmd.name = "Skybox";
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bool looksLikeSixSidedShader = true;
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looksLikeSixSidedShader &= (mat.passCount == 6); // should have six passes
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//looksLikeSixSidedShader &= !mat.GetShader()->GetShaderLabShader()->HasLightingPasses();
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if (looksLikeSixSidedShader)
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{
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Debug.LogWarning("Six sided skybox not yet supported.");
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}
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else
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{
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if (mesh == null)
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{
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CreateMesh();
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}
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float dist = camera.farClipPlane * 10.0f;
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Matrix4x4 world = Matrix4x4.TRS(camera.transform.position, Quaternion.identity, new Vector3(dist, dist, dist));
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Matrix4x4 skyboxProj = SkyboxHelper.GetProjectionMatrix(camera);
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cmd.SetProjectionAndViewMatrices(skyboxProj, camera.worldToCameraMatrix);
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cmd.DrawMesh(mesh, world, mat);
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cmd.SetProjectionAndViewMatrices(camera.projectionMatrix, camera.worldToCameraMatrix);
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}
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loop.ExecuteCommandBuffer(cmd);
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cmd.Dispose();
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}
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static public Matrix4x4 GetProjectionMatrix(Camera camera)
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{
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Matrix4x4 skyboxProj = Matrix4x4.Perspective(camera.fieldOfView, camera.aspect, camera.nearClipPlane, camera.farClipPlane);
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float nearPlane = camera.nearClipPlane * 0.01f;
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skyboxProj = AdjustDepthRange(skyboxProj, camera.nearClipPlane, nearPlane, camera.farClipPlane);
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return MakeProjectionInfinite(skyboxProj, nearPlane);
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}
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static Matrix4x4 MakeProjectionInfinite(Matrix4x4 m, float nearPlane)
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{
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const float epsilon = 1e-6f;
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Matrix4x4 r = m;
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r[2, 2] = -1.0f + epsilon;
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r[2, 3] = (-2.0f + epsilon) * nearPlane;
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r[3, 2] = -1.0f;
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return r;
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}
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static Matrix4x4 AdjustDepthRange(Matrix4x4 mat, float origNear, float newNear, float newFar)
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{
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float x = mat[0, 0];
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float y = mat[1, 1];
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float w = mat[0, 2];
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float z = mat[1, 2];
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float r = ((2.0f * origNear) / x) * ((w + 1) * 0.5f);
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float t = ((2.0f * origNear) / y) * ((z + 1) * 0.5f);
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float l = ((2.0f * origNear) / x) * (((w + 1) * 0.5f) - 1);
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float b = ((2.0f * origNear) / y) * (((z + 1) * 0.5f) - 1);
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float ratio = (newNear / origNear);
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r *= ratio;
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t *= ratio;
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l *= ratio;
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b *= ratio;
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Matrix4x4 ret = new Matrix4x4();
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ret[0, 0] = (2.0f * newNear) / (r - l); ret[0, 1] = 0; ret[0, 2] = (r + l) / (r - l); ret[0, 3] = 0;
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ret[1, 0] = 0; ret[1, 1] = (2.0f * newNear) / (t - b); ret[1, 2] = (t + b) / (t - b); ret[1, 3] = 0;
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ret[2, 0] = 0; ret[2, 1] = 0; ret[2, 2] = -(newFar + newNear) / (newFar - newNear); ret[2, 3] = -(2.0f * newFar * newNear) / (newFar - newNear);
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ret[3, 0] = 0; ret[3, 1] = 0; ret[3, 2] = -1.0f; ret[3, 3] = 0;
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return ret;
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}
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// Octahedron vertices
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Vector3[] octaVerts =
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{
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new Vector3(0.0f, 1.0f, 0.0f), new Vector3(0.0f, 0.0f, -1.0f), new Vector3(1.0f, 0.0f, 0.0f),
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new Vector3(0.0f, 1.0f, 0.0f), new Vector3(1.0f, 0.0f, 0.0f), new Vector3(0.0f, 0.0f, 1.0f),
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new Vector3(0.0f, 1.0f, 0.0f), new Vector3(0.0f, 0.0f, 1.0f), new Vector3(-1.0f, 0.0f, 0.0f),
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new Vector3(0.0f, 1.0f, 0.0f), new Vector3(-1.0f, 0.0f, 0.0f), new Vector3(0.0f, 0.0f, -1.0f),
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new Vector3(0.0f, -1.0f, 0.0f), new Vector3(1.0f, 0.0f, 0.0f), new Vector3(0.0f, 0.0f, -1.0f),
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new Vector3(0.0f, -1.0f, 0.0f), new Vector3(0.0f, 0.0f, 1.0f), new Vector3(1.0f, 0.0f, 0.0f),
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new Vector3(0.0f, -1.0f, 0.0f), new Vector3(-1.0f, 0.0f, 0.0f), new Vector3(0.0f, 0.0f, 1.0f),
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new Vector3(0.0f, -1.0f, 0.0f), new Vector3(0.0f, 0.0f, -1.0f), new Vector3(-1.0f, 0.0f, 0.0f),
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};
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Vector3 SubDivVert(Vector3 v1, Vector3 v2)
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{
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return Vector3.Normalize(v1 + v2);
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}
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void Subdivide(List<Vector3> dest, Vector3 v1, Vector3 v2, Vector3 v3)
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{
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Vector3 v12 = SubDivVert(v1, v2);
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Vector3 v23 = SubDivVert(v2, v3);
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Vector3 v13 = SubDivVert(v1, v3);
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dest.Add(v1);
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dest.Add(v12);
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dest.Add(v13);
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dest.Add(v12);
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dest.Add(v2);
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dest.Add(v23);
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dest.Add(v23);
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dest.Add(v13);
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dest.Add(v12);
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dest.Add(v3);
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dest.Add(v13);
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dest.Add(v23);
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}
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void SubdivideYOnly(List<Vector3> dest, Vector3 v1, Vector3 v2, Vector3 v3)
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{
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// Find out which vertex is furthest out from the others on the y axis
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float d12 = Mathf.Abs(v2.y - v1.y);
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float d23 = Mathf.Abs(v2.y - v3.y);
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float d31 = Mathf.Abs(v3.y - v1.y);
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Vector3 top, va, vb;
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if (d12 < d23 && d12 < d31)
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{
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top = v3;
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va = v1;
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vb = v2;
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}
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else if (d23 < d12 && d23 < d31)
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{
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top = v1;
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va = v2;
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vb = v3;
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}
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else
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{
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top = v2;
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va = v3;
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vb = v1;
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}
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Vector3 v12 = SubDivVert(top, va);
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Vector3 v13 = SubDivVert(top, vb);
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dest.Add(top);
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dest.Add(v12);
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dest.Add(v13);
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// A bit of extra logic to prevent triangle slivers: choose the shorter of (13->va), (12->vb) as triangle base
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if ((v13 - va).sqrMagnitude > (v12 - vb).sqrMagnitude)
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{
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dest.Add(v12);
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dest.Add(va);
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dest.Add(vb);
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dest.Add(v13);
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dest.Add(v12);
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dest.Add(vb);
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}
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else
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{
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dest.Add(v13);
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dest.Add(v12);
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dest.Add(va);
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dest.Add(v13);
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dest.Add(va);
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dest.Add(vb);
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}
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}
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Mesh _mesh;
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}
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