OpenGL绘图一个Hexigon顶点 [英] OpenGL drawing a Hexigon with vertices

问题描述

我试着做一个基本的形状（Hexigon）开始学习Android平台上关于OpenGL的一些基本知识和我有一个小问题。

Im trying to make a basic shape ( Hexigon ) to start and learn some basics about OpenGL on the Android platform and i have a little problem.

我已经成功地做​​了一个尖尖的六边形，但是当我将它转换成一个平面Hexygon它不正确呈现。下面是一些code，为你们找出问题（可能是一个很容易解决。）

I have successfully made a pointy Hexagon, but when i convert it into a flat Hexygon it doesnt render correctly. Here is some code, for you guys to figure out the problem ( probably a easy fix.. )

顶点/索引

//flat hexagon
private float verticesFlat[] = {     
    0.0f,   0.0f, 0.0f,    //center
    -0.5f,   1.0f, 0.0f,    // left top
    0.5f,   1.0f, 0.0f,    // right top
    1.0f,   0.0f, 0.0f,    // right
    0.5f,   1.0f, 0.0f,    // right bottom
    -0.5f,  -1.0f, 0.0f,    // left bottom
    -1.0f,   0.0f, 0.0f,     // left
};

private short[] indices = { 0, 1, 2, 3, 4, 5, 6, 1 };

标准顶点/索引缓冲。

standard vertex / index Buffers..

// a float is 4 bytes, therefore we multiply the number if
// vertices with 4.
ByteBuffer vbb = ByteBuffer.allocateDirect(verticesFlat.length * 4);
vbb.order(ByteOrder.nativeOrder());
vertexBuffer = vbb.asFloatBuffer();
vertexBuffer.put(verticesFlat);
vertexBuffer.position(0);

// short is 2 bytes, therefore we multiply the number if
// vertices with 2.
ByteBuffer ibb = ByteBuffer.allocateDirect(indices.length * 2);
ibb.order(ByteOrder.nativeOrder());
indexBuffer = ibb.asShortBuffer();
indexBuffer.put(indices);
indexBuffer.position(0);

本的OnDraw（GL10 GL）：

The onDraw(GL10 gl):

gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);

gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();

GLU.gluLookAt(gl, 0, 0, -5, 0f, 0f, 0f, 0f, 1.0f, 0.0f);    

gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);

gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer);
gl.glDrawElements(GL10.GL_TRIANGLE_FAN, indices.length, GL10.GL_UNSIGNED_SHORT, indexBuffer);

gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);

结果即时得到说明如下图所示：

The result im getting is illustrated in the image below:

推荐答案

应

private float verticesFlat[] = {     
    0.0f,   0.0f, 0.0f,    //center
    -0.5f,   1.0f, 0.0f,    // left top
    0.5f,   1.0f, 0.0f,    // right top
    1.0f,   0.0f, 0.0f,    // right
    0.5f,   -1.0f, 0.0f,    // right bottom (notice sign)
    -0.5f,  -1.0f, 0.0f,    // left bottom
    -1.0f,   0.0f, 0.0f,     // left
};

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