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87 lines
2.8 KiB
C#
87 lines
2.8 KiB
C#
// Copyright 2014-2017 ClassicalSharp | Licensed under BSD-3
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using System;
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using OpenTK;
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namespace ClassicalSharp {
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//http://www.crownandcutlass.com/features/technicaldetails/frustum.html
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public class FrustumCulling {
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float frustum00, frustum01, frustum02, frustum03,
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frustum10, frustum11, frustum12, frustum13,
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frustum20, frustum21, frustum22, frustum23,
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frustum30, frustum31, frustum32, frustum33,
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frustum40, frustum41, frustum42, frustum43;
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public bool SphereInFrustum(float x, float y, float z, float radius) {
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float d = frustum00 * x + frustum01 * y + frustum02 * z + frustum03;
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if (d <= -radius) return false;
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d = frustum10 * x + frustum11 * y + frustum12 * z + frustum13;
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if (d <= -radius) return false;
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d = frustum20 * x + frustum21 * y + frustum22 * z + frustum23;
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if (d <= -radius) return false;
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d = frustum30 * x + frustum31 * y + frustum32 * z + frustum33;
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if (d <= -radius) return false;
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d = frustum40 * x + frustum41 * y + frustum42 * z + frustum43;
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if (d <= -radius) return false;
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// Don't test NEAR plane, it's pointless
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return true;
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}
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public unsafe void CalcFrustumEquations(ref Matrix4 projection, ref Matrix4 modelView) {
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Matrix4 clipMatrix;
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Matrix4.Mult(ref modelView, ref projection, out clipMatrix);
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float* clip = (float*)&clipMatrix;
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// Extract the numbers for the RIGHT plane
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frustum00 = clip[3] - clip[0];
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frustum01 = clip[7] - clip[4];
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frustum02 = clip[11] - clip[8];
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frustum03 = clip[15] - clip[12];
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Normalise(ref frustum00, ref frustum01, ref frustum02, ref frustum03);
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// Extract the numbers for the LEFT plane
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frustum10 = clip[3] + clip[0];
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frustum11 = clip[7] + clip[4];
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frustum12 = clip[11] + clip[8];
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frustum13 = clip[15] + clip[12];
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Normalise(ref frustum10, ref frustum11, ref frustum12, ref frustum13);
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// Extract the BOTTOM plane
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frustum20 = clip[3] + clip[1];
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frustum21 = clip[7] + clip[5];
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frustum22 = clip[11] + clip[ 9];
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frustum23 = clip[15] + clip[13];
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Normalise(ref frustum20, ref frustum21, ref frustum22, ref frustum23);
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// Extract the TOP plane
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frustum30 = clip[3] - clip[1];
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frustum31 = clip[7] - clip[5];
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frustum32 = clip[11] - clip[9];
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frustum33 = clip[15] - clip[13];
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Normalise(ref frustum30, ref frustum31, ref frustum32, ref frustum33);
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// Extract the FAR plane
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frustum40 = clip[3] - clip[2];
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frustum41 = clip[7] - clip[6];
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frustum42 = clip[11] - clip[10];
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frustum43 = clip[15] - clip[14];
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Normalise(ref frustum40, ref frustum41, ref frustum42, ref frustum43);
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}
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void Normalise(ref float plane0, ref float plane1, ref float plane2, ref float plane3) {
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float val1 = plane0;
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float val2 = plane1;
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float val3 = plane2;
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float t = (float)Math.Sqrt(val1 * val1 + val2 * val2 + val3 * val3);
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plane0 /= t;
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plane1 /= t;
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plane2 /= t;
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plane3 /= t;
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}
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}
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} |