jme3utilities.mesh.Prism Maven / Gradle / Ivy
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/*
Copyright (c) 2019-2023, Stephen Gold
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* Neither the name of the copyright holder nor the names of its contributors
may be used to endorse or promote products derived from this software without
specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package jme3utilities.mesh;
import com.jme3.math.FastMath;
import com.jme3.scene.Mesh;
import com.jme3.scene.VertexBuffer;
import com.jme3.util.BufferUtils;
import java.nio.FloatBuffer;
import java.util.logging.Logger;
import jme3utilities.MyMesh;
import jme3utilities.Validate;
import jme3utilities.math.MyMath;
/**
* A 3-D, static, Triangles-mode Mesh (without indices or texture coordinates)
* that renders a prism.
*
* @author Stephen Gold [email protected]
* @see com.jme3.scene.shape.Cylinder
*/
public class Prism extends Mesh {
// *************************************************************************
// constants and loggers
/**
* number of axes in a vector
*/
final private static int numAxes = 3;
/**
* message logger for this class
*/
final public static Logger logger
= Logger.getLogger(Prism.class.getName());
// *************************************************************************
// constructors
/**
* No-argument constructor needed by SavableClassUtil.
*/
protected Prism() {
}
/**
* Instantiate a right prism, closed at both ends with regular polygons.
*
* The center is at (0,0,0). The end polygons lie parallel with the X-Z
* plane. All triangles face outward.
*
* @param numSides the desired number of sides for each end (≥3)
* @param radius the desired radius of each end (in mesh units, >0)
* @param yHeight the desired total height of the prism on the Y axis (in
* mesh units, >0)
* @param generateNormals true → generate normals, false → no
* normals
*/
public Prism(int numSides, float radius, float yHeight,
boolean generateNormals) {
Validate.inRange(numSides, "number of sides", 3, Integer.MAX_VALUE);
Validate.positive(radius, "radius");
Validate.positive(yHeight, "height");
int numEndTriangles = 2 * (numSides - 2);
int numSideTriangles = 2 * numSides;
int numTriangles = numEndTriangles + numSideTriangles;
int numFloats = numTriangles * MyMesh.vpt * numAxes;
FloatBuffer positionBuffer = BufferUtils.createFloatBuffer(numFloats);
setBuffer(VertexBuffer.Type.Position, numAxes, positionBuffer);
float y = yHeight / 2f;
float interiorAngle = FastMath.TWO_PI / numSides; // in radians
for (int sideIndex = 0; sideIndex < numSides; ++sideIndex) {
float theta1 = sideIndex * interiorAngle; // in radians
float x1 = radius * FastMath.sin(theta1);
float z1 = radius * FastMath.cos(theta1);
int nextSideIndex = MyMath.modulo(sideIndex + 1, numSides);
float theta2 = nextSideIndex * interiorAngle; // in radians
float x2 = radius * FastMath.sin(theta2);
float z2 = radius * FastMath.cos(theta2);
positionBuffer.put(x2).put(+y).put(z2);
positionBuffer.put(x1).put(+y).put(z1);
positionBuffer.put(x2).put(-y).put(z2);
positionBuffer.put(x1).put(+y).put(z1);
positionBuffer.put(x1).put(-y).put(z1);
positionBuffer.put(x2).put(-y).put(z2);
if (sideIndex < numSides - 2) {
float theta3 = (numSides - 1) * interiorAngle; // in radians
float x3 = radius * FastMath.sin(theta3);
float z3 = radius * FastMath.cos(theta3);
positionBuffer.put(x1).put(+y).put(z1);
positionBuffer.put(x2).put(+y).put(z2);
positionBuffer.put(x3).put(+y).put(z3);
positionBuffer.put(x3).put(-y).put(z3);
positionBuffer.put(x2).put(-y).put(z2);
positionBuffer.put(x1).put(-y).put(z1);
}
}
positionBuffer.flip();
assert positionBuffer.limit() == positionBuffer.capacity();
if (generateNormals) {
MyMesh.generateFacetNormals(this);
}
updateBound();
setStatic();
}
/**
* Instantiate a right prism, closed at both ends with right triangles.
*
* The midpoint of the edge joining the right angles of the triangles is at
* (0,0,0). The end triangles lie parallel with the X-Z plane. All triangles
* face outward.
*
* Normals are not generated. If normals are needed, add them using
* {@link jme3utilities.MyMesh#generateFacetNormals(com.jme3.scene.Mesh)}.
*
* @param x the desired length of the legs parallel to the X axis (in mesh
* units, >0)
* @param yHeight the desired total height of the prism on the Y axis (in
* mesh units, >0)
* @param z the desired length of the legs parallel to the Z axis (in mesh
* units, >0)
*/
public Prism(float x, float yHeight, float z) {
Validate.positive(x, "x length");
Validate.positive(yHeight, "height");
Validate.positive(z, "z length");
int numTriangles = 8;
int numFloats = numTriangles * MyMesh.vpt * numAxes;
FloatBuffer positionBuffer = BufferUtils.createFloatBuffer(numFloats);
setBuffer(VertexBuffer.Type.Position, numAxes, positionBuffer);
float y = yHeight / 2f;
// top (right triangle)
positionBuffer.put(0f).put(+y).put(0f);
positionBuffer.put(0f).put(+y).put(z);
positionBuffer.put(x).put(+y).put(0f);
// base (right triangle)
positionBuffer.put(0f).put(-y).put(0f);
positionBuffer.put(x).put(-y).put(0f);
positionBuffer.put(0f).put(-y).put(z);
// rectangle containing the hypotenuses
positionBuffer.put(x).put(+y).put(0f);
positionBuffer.put(0f).put(+y).put(z);
positionBuffer.put(0f).put(-y).put(z);
positionBuffer.put(0f).put(-y).put(z);
positionBuffer.put(x).put(-y).put(0f);
positionBuffer.put(x).put(+y).put(0f);
// rectangle containing the legs parallel to the X axis
positionBuffer.put(0f).put(+y).put(0f);
positionBuffer.put(x).put(+y).put(0f);
positionBuffer.put(x).put(-y).put(0f);
positionBuffer.put(x).put(-y).put(0f);
positionBuffer.put(0f).put(-y).put(0f);
positionBuffer.put(0f).put(+y).put(0f);
// rectangle containing the legs parallel to the Z axis
positionBuffer.put(0f).put(+y).put(z);
positionBuffer.put(0f).put(+y).put(0f);
positionBuffer.put(0f).put(-y).put(0f);
positionBuffer.put(0f).put(-y).put(0f);
positionBuffer.put(0f).put(-y).put(z);
positionBuffer.put(0f).put(+y).put(z);
positionBuffer.flip();
assert positionBuffer.limit() == positionBuffer.capacity();
updateBound();
setStatic();
}
}