[ Android 3D Animation (3)] min3d立體方塊Box類別的程式解說

在前一篇文章中我們說明如何利用Box來建立立體方塊，那Box又是什麼呢？我們來追蹤Box程式，首先您可以發現Box是min3d.objectPrimitives套件下的某一類別，Box的父類別就是3D物件的容器Object3dContainer，此類別有4個屬性，如下列所示：
private Color4[] _cols; //儲存顏色
private float _width; //寬度
private float _height; //高度
private float _depth; //深度

以下是Box4個建構子，當Box物件被建立時建構子會被呼叫用來初始化該物件
public Box(float $width, float $height, float $depth, Color4[] $sixColor4s, Boolean $useUvs, Boolean $useNormals, Boolean $useVertexColors)
public Box(float $width, float $height, float $depth, Color4[] $sixColor4s)
public Box(float $width, float $height, float $depth, Color4 color)
public Box(float $width, float $height, float $depth)

該類別內只有1個函式make()，用來建立立體方塊。

以下是Box類別的程式列表：

package min3d.objectPrimitives;

import min3d.Utils;
import min3d.core.Object3dContainer;
import min3d.vos.Color4;


/**
 * Note how each 'face' (quad) of the box uses its own set of 4 vertices each, 
 * rather than sharing with adjacent faces.  This allows for each face to be 
 * texture mapped, normal'ed, and colored independently of the others. 
 * 
 * Object origin is center of box. 
 */
public class Box extends Object3dContainer
{
 private Color4[] _cols;
 private float _width;
 private float _height;
 private float _depth;
 

 public Box(float $width, float $height, float $depth, Color4[] $sixColor4s, Boolean $useUvs, Boolean $useNormals, Boolean $useVertexColors)
 {
  super(4*6, 2*6, $useUvs,$useNormals,$useVertexColors);
  
  _width = $width;
  _height = $height;
  _depth = $depth;
  
  if ($sixColor4s != null)
  {
   _cols = $sixColor4s;
  }
  else
  {
   _cols = new Color4[6];
   _cols[0] = new Color4(255,0,0,255);
   _cols[1] = new Color4(0,255,0,255);
   _cols[2] = new Color4(0,0,255,255);
   _cols[3] = new Color4(255,255,0,255);
   _cols[4] = new Color4(0,255,255,255);
   _cols[5] = new Color4(255,0,255,255);
  }
  
  make();
 }
 
 public Box(float $width, float $height, float $depth, Color4[] $sixColor4s)
 {
  this($width,$height,$depth, $sixColor4s, true,true,true);
 }
 
 public Box(float $width, float $height, float $depth, Color4 color)
 {
  this($width,$height,$depth, new Color4[] { color, color, color, color, color, color }, true,true,true);
 }

 public Box(float $width, float $height, float $depth)
 {
  this($width,$height,$depth, null,  true,true,true);
 }

 private void make()
 {
  float w = _width / 2f;
  float h = _height / 2f;
  float d = _depth / 2f;

  short ul, ur, lr, ll;
  
  // front
  ul = this.vertices().addVertex(-w,+h,+d, 0f,0f, 0,0,1, _cols[0].r,_cols[0].g,_cols[0].b,_cols[0].a);
  ur = this.vertices().addVertex(+w,+h,+d, 1f,0f, 0,0,1, _cols[0].r,_cols[0].g,_cols[0].b,_cols[0].a);
  lr = this.vertices().addVertex(+w,-h,+d, 1f,1f, 0,0,1, _cols[0].r,_cols[0].g,_cols[0].b,_cols[0].a);
  ll = this.vertices().addVertex(-w,-h,+d, 0f,1f, 0,0,1, _cols[0].r,_cols[0].g,_cols[0].b,_cols[0].a);
  Utils.addQuad(this, ul,ur,lr,ll);
  
  // right
  ul = this.vertices().addVertex(+w,+h,+d, 0f,0f, 1,0,0, _cols[1].r,_cols[1].g,_cols[1].b,_cols[1].a);
  ur = this.vertices().addVertex(+w,+h,-d, 1f,0f, 1,0,0, _cols[1].r,_cols[1].g,_cols[1].b,_cols[1].a);
  lr = this.vertices().addVertex(+w,-h,-d, 1f,1f, 1,0,0, _cols[1].r,_cols[1].g,_cols[1].b,_cols[1].a);
  ll = this.vertices().addVertex(+w,-h,+d, 0f,1f, 1,0,0, _cols[1].r,_cols[1].g,_cols[1].b,_cols[1].a);
  Utils.addQuad(this, ul,ur,lr,ll);

  // back
  ul = this.vertices().addVertex(+w,+h,-d, 0f,0f, 0,0,-1, _cols[2].r,_cols[2].g,_cols[2].b,_cols[2].a);
  ur = this.vertices().addVertex(-w,+h,-d, 1f,0f, 0,0,-1, _cols[2].r,_cols[2].g,_cols[2].b,_cols[2].a);
  lr = this.vertices().addVertex(-w,-h,-d, 1f,1f, 0,0,-1, _cols[2].r,_cols[2].g,_cols[2].b,_cols[2].a);
  ll = this.vertices().addVertex(+w,-h,-d, 0f,1f, 0,0,-1, _cols[2].r,_cols[2].g,_cols[2].b,_cols[2].a);
  Utils.addQuad(this, ul,ur,lr,ll);
 
  // left
  ul = this.vertices().addVertex(-w,+h,-d, 0f,0f, -1,0,0, _cols[3].r,_cols[3].g,_cols[3].b,_cols[3].a);
  ur = this.vertices().addVertex(-w,+h,+d, 1f,0f, -1,0,0, _cols[3].r,_cols[3].g,_cols[3].b,_cols[3].a);
  lr = this.vertices().addVertex(-w,-h,+d, 1f,1f, -1,0,0, _cols[3].r,_cols[3].g,_cols[3].b,_cols[3].a);
  ll = this.vertices().addVertex(-w,-h,-d, 0f,1f, -1,0,0, _cols[3].r,_cols[3].g,_cols[3].b,_cols[3].a);
  Utils.addQuad(this, ul,ur,lr,ll);
  
  // top
  ul = this.vertices().addVertex(-w,+h,-d, 0f,0f, 0,1,0, _cols[4].r,_cols[4].g,_cols[4].b,_cols[4].a);
  ur = this.vertices().addVertex(+w,+h,-d, 1f,0f, 0,1,0, _cols[4].r,_cols[4].g,_cols[4].b,_cols[4].a);
  lr = this.vertices().addVertex(+w,+h,+d, 1f,1f, 0,1,0, _cols[4].r,_cols[4].g,_cols[4].b,_cols[4].a);
  ll = this.vertices().addVertex(-w,+h,+d, 0f,1f, 0,1,0, _cols[4].r,_cols[4].g,_cols[4].b,_cols[4].a);
  Utils.addQuad(this, ul,ur,lr,ll);

  // bottom
  ul = this.vertices().addVertex(-w,-h,+d, 0f,0f, 0,-1,0, _cols[5].r,_cols[5].g,_cols[5].b,_cols[5].a);
  ur = this.vertices().addVertex(+w,-h,+d, 1f,0f, 0,-1,0, _cols[5].r,_cols[5].g,_cols[5].b,_cols[5].a);
  lr = this.vertices().addVertex(+w,-h,-d, 1f,1f, 0,-1,0, _cols[5].r,_cols[5].g,_cols[5].b,_cols[5].a);
  ll = this.vertices().addVertex(-w,-h,-d, 0f,1f, 0,-1,0, _cols[5].r,_cols[5].g,_cols[5].b,_cols[5].a);
  Utils.addQuad(this, ul,ur,lr,ll);
 }
}