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   1 /*
   2  * Sixth 3D engine. Author: Svjatoslav Agejenko.
   3  * This project is released under Creative Commons Zero (CC0) license.
   4  */
   5 package eu.svjatoslav.sixth.e3d.renderer.raster.shapes.composite.solid;
   6
   7 import eu.svjatoslav.sixth.e3d.geometry.Point3D;
   8 import eu.svjatoslav.sixth.e3d.renderer.raster.Color;
   9 import eu.svjatoslav.sixth.e3d.renderer.raster.shapes.basic.solidpolygon.SolidPolygon;
  10 import eu.svjatoslav.sixth.e3d.renderer.raster.shapes.composite.base.AbstractCompositeShape;
  11
  12 /**
  13  * A solid square-based pyramid with the base centered at a given point.
  14  *
  15  * <p>The pyramid has a square base and four triangular faces meeting at an apex.
  16  * The base has side length of {@code 2 * baseSize} and the height extends
  17  * {@code height} units above the base center to the apex.</p>
  18  *
  19  * <p><b>Usage example:</b></p>
  20  * <pre>{@code
  21  * SolidPolygonPyramid pyramid = new SolidPolygonPyramid(
  22  *         new Point3D(0, 0, 300), 50, 100, Color.BLUE);
  23  * shapeCollection.addShape(pyramid);
  24  * }</pre>
  25  *
  26  * @see SolidPolygonCube
  27  * @see SolidPolygonSphere
  28  * @see SolidPolygon
  29  */
  30 public class SolidPolygonPyramid extends AbstractCompositeShape {
  31
  32     /**
  33      * Constructs a solid square-based pyramid with base centered at the given point.
  34      *
  35      * @param baseCenter the center point of the pyramid's base in 3D space
  36      * @param baseSize   the half-width of the square base; the base extends
  37      *                   this distance from the center along X and Z axes,
  38      *                   giving a total base edge length of {@code 2 * baseSize}
  39      * @param height     the height of the pyramid from base center to apex
  40      * @param color      the fill color applied to all faces of the pyramid
  41      */
  42     public SolidPolygonPyramid(final Point3D baseCenter, final double baseSize,
  43                                final double height, final Color color) {
  44         super();
  45
  46         final double halfBase = baseSize;
  47         final double apexY = baseCenter.y - height;
  48         final double baseY = baseCenter.y;
  49
  50         Point3D frontLeft = new Point3D(baseCenter.x - halfBase, baseY, baseCenter.z - halfBase);
  51         Point3D frontRight = new Point3D(baseCenter.x + halfBase, baseY, baseCenter.z - halfBase);
  52         Point3D backRight = new Point3D(baseCenter.x + halfBase, baseY, baseCenter.z + halfBase);
  53         Point3D backLeft = new Point3D(baseCenter.x - halfBase, baseY, baseCenter.z + halfBase);
  54         Point3D apex = new Point3D(baseCenter.x, apexY, baseCenter.z);
  55
  56         // Polygons that touch apex
  57         addShape(new SolidPolygon(frontLeft, frontRight, apex, color));
  58         addShape(new SolidPolygon(frontRight, backRight, apex, color));
  59         addShape(new SolidPolygon(backRight, backLeft, apex, color));
  60         addShape(new SolidPolygon(backLeft, frontLeft, apex, color));
  61
  62         // Pyramid bottom
  63         addShape(new SolidPolygon( backLeft, backRight, frontLeft, color));
  64         addShape(new SolidPolygon( frontRight, frontLeft, backRight, color));
  65
  66         setBackfaceCulling(true);
  67     }
  68 }