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capdevoncapdevon
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added Circle class
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  • jme3-core/src/main/java/com/jme3/environment/util

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‎jme3-core/src/main/java/com/jme3/environment/util/Circle.java‎

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/*
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* Copyright (c) 2009-2025 jMonkeyEngine
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* * Neither the name of 'jMonkeyEngine' nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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package com.jme3.environment.util;
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import com.jme3.asset.AssetManager;
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import com.jme3.material.Material;
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import com.jme3.material.RenderState;
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import com.jme3.math.ColorRGBA;
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import com.jme3.math.FastMath;
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import com.jme3.renderer.queue.RenderQueue;
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import com.jme3.scene.Geometry;
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import com.jme3.scene.Mesh;
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import com.jme3.scene.VertexBuffer.Type;
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import com.jme3.util.BufferUtils;
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import java.nio.FloatBuffer;
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import java.nio.ShortBuffer;
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/**
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* <p>A `Circle` is a 2D mesh representing a circular outline (wireframe).
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* It's defined by a specified number of radial samples, which determine its smoothness.</p>
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*
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* <p>The circle is centered at (0,0,0) in its local coordinate space and has a radius of 1.0.</p>
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*/
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public class Circle extends Mesh {
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// The number of segments used to approximate the circle.
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protected int radialSamples = 256;
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/**
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* Creates a new `Circle` mesh.
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*/
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public Circle() {
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setGeometryData();
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setIndexData();
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}
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/**
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* Creates a new `Circle` mesh with the specified number of radial samples.
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* The circle will be centered at (0,0,0) with a radius of 1.0.
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*
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* @param radialSamples The number of segments (vertices) to use for the circle's perimeter.
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* @throws IllegalArgumentException if `radialSamples` is less than 2.
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*/
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public Circle(int radialSamples) {
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if (radialSamples < 2) {
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throw new IllegalArgumentException("radialSamples must be at least 2 for a valid circle.");
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}
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this.radialSamples = radialSamples;
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setGeometryData();
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setIndexData();
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}
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/**
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* builds the vertices based on the radius.
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*/
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private void setGeometryData() {
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setMode(Mode.Lines);
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FloatBuffer posBuf = BufferUtils.createVector3Buffer((radialSamples + 1));
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FloatBuffer colBuf = BufferUtils.createFloatBuffer((radialSamples + 1) * 4);
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FloatBuffer texBuf = BufferUtils.createVector2Buffer(radialSamples + 1);
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setBuffer(Type.Position, 3, posBuf);
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setBuffer(Type.Color, 4, colBuf);
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setBuffer(Type.TexCoord, 2, texBuf);
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// generate geometry
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float fInvRS = 1.0f / radialSamples;
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// Generate points on the unit circle to be used in computing the mesh
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// points on a sphere slice.
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float[] sin = new float[(radialSamples + 1)];
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float[] cos = new float[(radialSamples + 1)];
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for (int i = 0; i < radialSamples; i++) {
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float angle = FastMath.TWO_PI * fInvRS * i;
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cos[i] = FastMath.cos(angle);
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sin[i] = FastMath.sin(angle);
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}
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sin[radialSamples] = sin[0];
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cos[radialSamples] = cos[0];
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ColorRGBA color = ColorRGBA.Orange;
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for (int iR = 0; iR <= radialSamples; iR++) {
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posBuf.put(cos[iR]).put(sin[iR]).put(0);
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colBuf.put(color.r).put(color.g).put(color.b).put(color.a);
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texBuf.put(iR % 2f).put(iR % 2f);
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}
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updateBound();
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setStatic();
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}
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/**
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* sets the indices for rendering the circle.
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*/
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private void setIndexData() {
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// allocate connectivity
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int nbSegments = (radialSamples);
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ShortBuffer idxBuf = BufferUtils.createShortBuffer(2 * nbSegments);
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setBuffer(Type.Index, 2, idxBuf);
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int idx = 0;
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int segDone = 0;
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while (segDone < nbSegments) {
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idxBuf.put((short) idx);
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idxBuf.put((short) (idx + 1));
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idx++;
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segDone++;
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}
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}
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/**
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* Creates a {@link Geometry} object representing a dashed wireframe circle.
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*
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* @param assetManager The application's AssetManager to load materials.
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* @param name The desired name for the Geometry.
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* @return A new Geometry instance with a `Circle` mesh.
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*/
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public static Geometry createShape(AssetManager assetManager, String name) {
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return createShape(assetManager, name, 256);
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}
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/**
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* Creates a {@link Geometry} object representing a dashed wireframe circle
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* with a specified number of radial samples.
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*
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* @param assetManager The application's AssetManager to load materials.
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* @param name The desired name for the Geometry.
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* @param radialSamples The number of segments to use for the circle's perimeter.
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* @return A new Geometry instance with a `Circle` mesh.
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*/
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public static Geometry createShape(AssetManager assetManager, String name, int radialSamples) {
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Circle mesh = new Circle(radialSamples);
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Geometry geom = new Geometry(name, mesh);
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geom.setQueueBucket(RenderQueue.Bucket.Transparent);
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Material mat = new Material(assetManager, "Common/MatDefs/Dashed/dashed.j3md");
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mat.getAdditionalRenderState().setWireframe(true);
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mat.getAdditionalRenderState().setBlendMode(RenderState.BlendMode.Alpha);
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mat.getAdditionalRenderState().setDepthWrite(false);
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mat.getAdditionalRenderState().setDepthTest(false);
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mat.getAdditionalRenderState().setLineWidth(2f);
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mat.setColor("Color", ColorRGBA.Orange);
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mat.setFloat("DashSize", 0.5f);
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geom.setMaterial(mat);
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return geom;
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}
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}

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