Android Open Source - GLaunchy3 Shape Builder

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License

The source code is released under:

Apache License

Java Source Code

package com.frak.glaunchy.common;
/*w w  w  .j ava2 s .  com*/
public class ShapeBuilder 
{
  public static float[] generateCubeData(float[] point1,
      float[] point2,
      float[] point3,
      float[] point4,
      float[] point5,
      float[] point6,
      float[] point7,
      float[] point8,
      int elementsPerPoint)
  {
    // Given a cube with the points defined as follows:
    // front left top, front right top, front left bottom, front right bottom,
    // back left top, back right top, back left bottom, back right bottom,    
    // return an array of 6 sides, 2 triangles per side, 3 vertices per triangle, and 4 floats per vertex.
    final int FRONT = 0;
    final int RIGHT = 1;
    final int BACK = 2;
    final int LEFT = 3;
    final int TOP = 4;
    final int BOTTOM = 5;

    final int size = elementsPerPoint * 6 * 6;
    final float[] cubeData = new float[size];    

    for (int face = 0; face < 6; face ++)
    {
      // Relative to the side, p1 = top left, p2 = top right, p3 = bottom left, p4 = bottom right
      final float[] p1, p2, p3, p4;

      // Select the points for this face
      if (face == FRONT)
      {
        p1 = point1; p2 = point2; p3 = point3; p4 = point4; 
      }
      else if (face == RIGHT)
      {
        p1 = point2; p2 = point6; p3 = point4; p4 = point8;
      }
      else if (face == BACK)
      {
        p1 = point6; p2 = point5; p3 = point8; p4 = point7;
      }
      else if (face == LEFT)
      {
        p1 = point5; p2 = point1; p3 = point7; p4 = point3;
      }
      else if (face == TOP)
      {
        p1 = point5; p2 = point6; p3 = point1; p4 = point2;
      }
      else // if (side == BOTTOM)
      {
        p1 = point8; p2 = point7; p3 = point4; p4 = point3;                
      }
      
      // In OpenGL counter-clockwise winding is default. This means that when we look at a triangle, 
      // if the points are counter-clockwise we are looking at the "front". If not we are looking at
      // the back. OpenGL has an optimization where all back-facing triangles are culled, since they
      // usually represent the backside of an object and aren't visible anyways.

      // Build the triangles
      //  1---3,6
      //  | / |
      // 2,4--5
      int offset = face * elementsPerPoint * 6;

      for (int i = 0; i < elementsPerPoint; i++) { cubeData[offset++] = p1[i]; }
      for (int i = 0; i < elementsPerPoint; i++) { cubeData[offset++] = p3[i]; }
      for (int i = 0; i < elementsPerPoint; i++) { cubeData[offset++] = p2[i]; }
      for (int i = 0; i < elementsPerPoint; i++) { cubeData[offset++] = p3[i]; }
      for (int i = 0; i < elementsPerPoint; i++) { cubeData[offset++] = p4[i]; }
      for (int i = 0; i < elementsPerPoint; i++) { cubeData[offset++] = p2[i]; }
    }

    return cubeData;
  }
}

Java Source Code List

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