Android 真正的3D图形(一)

Android 真正的3D图形（一）

Design设计

在使用OpenGL 框架时一个好的设计原则是使用“Composite Pattern”，本篇采用如下设计：

Mesh

首先定义一个基类Mesh,所有空间形体最基本的构成元素为Mesh（三角形网格），其基本定义如下：

Java代码：

Java代码

1publicclassMesh{

2//Ourvertexbuffer.

3privateFloatBufferverticesBuffer=null;

4

5//Ourindexbuffer.

6privateShortBufferindicesBuffer=null;

7

8//Thenumberofindices.

9privateintnumOfIndices=-1;

10

11//FlatColor

12privatefloat[]rgba

13=newfloat[]{1.0f,1.0f,1.0f,1.0f};

14

15//SmoothColors

16privateFloatBuffercolorBuffer=null;

17

18//Translateparams.

19publicfloatx=0;

20

21publicfloaty=0;

22

23publicfloatz=0;

24

25//Rotateparams.

26publicfloatrx=0;

27

28publicfloatry=0;

29

30publicfloatrz=0;

31

32publicvoiddraw(GL10gl){

33//Counter-clockwisewinding.

34gl.glFrontFace(GL10.GL_CCW);

35//Enablefaceculling.

36gl.glEnable(GL10.GL_CULL_FACE);

37//Whatfacestoremovewiththefaceculling.

38gl.glCullFace(GL10.GL_BACK);

39//Enabledtheverticesbufferforwritingand

40//tobeusedduring

41//rendering.

42gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);

43//Specifiesthelocationanddataformat

44//ofanarrayofvertex

45//coordinatestousewhenrendering.

46gl.glV ertexPointer(3,GL10.GL_FLOA T,0,verticesBuffer); 47//Setflatcolor

48gl.glColor4f(rgba[0],rgba[1],rgba[2],rgba[3]);

49//Smoothcolor

50if(colorBuffer!=null){

51//Enablethecolorarraybuffertobe

52//usedduringrendering.

53gl.glEnableClientState(GL10.GL_COLOR_ARRAY);

54gl.glColorPointer(4,GL10.GL_FLOA T,0,colorBuffer); 55}

56

57gl.glTranslatef(x,y,z);

58gl.glRotatef(rx,1,0,0);

59gl.glRotatef(ry,0,1,0);

60gl.glRotatef(rz,0,0,1);

61

62//Pointoutthewherethecolorbufferis.

63gl.glDrawElements(GL10.GL_TRIANGLES,numOfIndices, 64GL10.GL_UNSIGNED_SHORT,indicesBuffer);

65//Disabletheverticesbuffer.

66gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);

67//Disablefaceculling.

68gl.glDisable(GL10.GL_CULL_FACE);

69}

70

71protectedvoidsetV ertices(float[]vertices){

72//afloatis4bytes,therefore

73//wemultiplythenumberif

74//verticeswith4.

75ByteBuffervbb

76=ByteBuffer.allocateDirect(vertices.length*4);

77vbb.order(ByteOrder.nativeOrder());

78verticesBuffer=vbb.asFloatBuffer();

79verticesBuffer.put(vertices);

80verticesBuffer.position(0);

81}

82

83protectedvoidsetIndices(short[]indices){

84//shortis2bytes,thereforewemultiply

85//thenumberif

86//verticeswith2.

87ByteBufferibb

88=ByteBuffer.allocateDirect(indices.length*2);

89ibb.order(ByteOrder.nativeOrder());

90indicesBuffer=ibb.asShortBuffer();

91indicesBuffer.put(indices);

92indicesBuffer.position(0);

93numOfIndices=indices.length;

94}

95

96protectedvoidsetColor(floatred,floatgreen,

97floatblue,floatalpha){

98//Settingtheflatcolor.

99rgba[0]=red;

100rgba[1]=green;

101rgba[2]=blue;

102rgba[3]=alpha;

103}

104

105protectedvoidsetColors(float[]colors){

106//floathas4bytes.

107ByteBuffercbb

108=ByteBuffer.allocateDirect(colors.length*4);

109cbb.order(ByteOrder.nativeOrder());

110colorBuffer=cbb.asFloatBuffer();

111colorBuffer.put(colors);

112colorBuffer.position(0);

113}

114}

* setV ertices 允许子类重新定义顶点坐标。

* setIndices 允许子类重新定义顶点的顺序。