Reputation: 7696
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.
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.. )
vertices / indices
//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 };
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);
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);
The result im getting is illustrated in the image below:
Upvotes: 1
Views: 10225
Reputation: 2138
Should be
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
};
Upvotes: 2