83 lines
2.8 KiB
C#
83 lines
2.8 KiB
C#
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using System;
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using System.Collections.Generic;
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using System.Numerics;
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namespace Csharp_3d_viewer
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{
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public class SphereRenderer : TriangleRenderer
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{
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private const float radius = 1.0f;
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private const int MinSectorCount = 3;
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private const int MinStackCount = 2;
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public SphereRenderer(int sectorCount = 36, int stackCount = 18)
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{
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sectorCount = Math.Max(sectorCount, MinSectorCount);
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stackCount = Math.Max(stackCount, MinStackCount);
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BuildVertices(sectorCount, stackCount, out var vertices, out var indices);
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UpdateTriangles(vertices, indices);
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}
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public void Render(Vector3 position, float radius, Vector4 color)
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{
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var model = Matrix4x4.CreateScale(radius) * Matrix4x4.CreateTranslation(position);
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Render(model, color);
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}
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private void BuildVertices(int sectorCount, int stackCount, out Vertex[] vertices, out int[] indices)
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{
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var radiusInv = 1.0f / radius;
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var sectorStep = (float)(2 * Math.PI / sectorCount);
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var stackStep = Math.PI / stackCount;
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var sphereVertices = new List<Vertex>();
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for (int i = 0; i <= stackCount; ++i)
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{
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Vector3 position = new Vector3();
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var stackAngle = (float)(Math.PI / 2 - i * stackStep);
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var xy = radius * Math.Cos(stackAngle);
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position.Z = (float)(radius * Math.Sin(stackAngle));
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for (int j = 0; j <= sectorCount; ++j)
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{
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var sectorAngle = j * sectorStep;
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position.X = (float)(xy * Math.Cos(sectorAngle));
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position.Y = (float)(xy * Math.Sin(sectorAngle));
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Vector3 normal = new Vector3(position.X, position.Y, position.Z) * radiusInv;
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sphereVertices.Add(new Vertex { Position = position, Normal = normal });
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}
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}
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vertices = sphereVertices.ToArray();
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var sphereIndices = new List<int>();
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for (int i = 0; i < stackCount; ++i)
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{
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var k1 = i * (sectorCount + 1);
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var k2 = k1 + sectorCount + 1;
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for (int j = 0; j < sectorCount; ++j, ++k1, ++k2)
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{
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if (i != 0)
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{
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sphereIndices.Add(k1);
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sphereIndices.Add(k2);
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sphereIndices.Add(k1 + 1);
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}
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if (i != (stackCount - 1))
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{
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sphereIndices.Add(k1 + 1);
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sphereIndices.Add(k2);
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sphereIndices.Add(k2 + 1);
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}
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}
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}
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indices = sphereIndices.ToArray();
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}
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}
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}
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