如何在OpenGL ES中移动带有纹理的形状？

Question

How can I move the shape? I have tried changing the float that holds all the vertices but it didnt work... Then I have tried glTranslateF, but it didnt work either. What am I doing wrong?

Here is my code:

package com.chrypthic.android.reference;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.ShortBuffer;

import javax.microedition.khronos.opengles.GL10;

import android.content.Context;
import android.util.Log;

public class Square
{
final int VERTEX_SIZE = (2+2) *4;
FloatBuffer vertices;
ShortBuffer indices;

Texture texture;

GL10 gl;
Context c;

int x;
int y;
int w;
int h;

public Square(GL10 gl, Context context, int x, int y, int w, int h, String imageTexture)
{
    this.gl = gl;
    this.c = context;

    this.x = x;
    this.y = y;
    this.w = w;
    this.h = h;

    ByteBuffer byteBuffer = ByteBuffer.allocateDirect(4 * VERTEX_SIZE);
    byteBuffer.order(ByteOrder.nativeOrder());
    vertices = byteBuffer.asFloatBuffer();
    /*vertices.put(new float[]{
        10.0f, 10.0f, 0.0f, 1.0f, //bl  
        160.0f, 10.0f, 1.0f, 1.0f, //br 
        160.0f, 160.0f, 1.0f, 0.0f, //tr    
        10.0f, 160.0f, 0.0f, 0.0f, //tl 
    });*/
    vertices.put(new float[]{
            (float)x, ((float)y+(float)h), 0.0f, 1.0f, //bl 
            ((float)x+(float)w), ((float)y+(float)h), 1.0f, 1.0f, //br  
            ((float)x+(float)w), (float)y, 1.0f, 0.0f, //tr 
            (float)x, (float)y, 0.0f, 0.0f, //tl    
        });
    vertices.flip();

    byteBuffer = ByteBuffer.allocateDirect(6 * 2);
    byteBuffer.order(ByteOrder.nativeOrder());
    indices = byteBuffer.asShortBuffer();
    indices.put(new short[]{
        0, 1, 2, 2, 3, 0
    });
    indices.flip();

    texture = new Texture(imageTexture, c, gl);
    texture.load();
}

public void draw()
{
    gl.glMatrixMode(GL10.GL_PROJECTION);
    gl.glEnable(GL10.GL_TEXTURE_2D);
    texture.bind();
    gl.glColor4f(0f, 0f, 0f, 1f);

    gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
    gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);

    vertices.position(0);
    gl.glVertexPointer(2, GL10.GL_FLOAT, VERTEX_SIZE, vertices);
    vertices.position(2);
    gl.glTexCoordPointer(2, GL10.GL_FLOAT, VERTEX_SIZE, vertices);

    gl.glDrawElements(GL10.GL_TRIANGLES, 6, GL10.GL_UNSIGNED_SHORT, indices);
}

public void update()
{
    //this doesnt work. I call the method every 10 milliseconds from a thread in another class.
    gl.glEnable(GL10.GL_TEXTURE_2D);
    gl.glTranslatef(10, y, 0);
}
}

Answer 1

The problem in the source you provided was the fact that glTranslatef needs to be called before performing the draw operation. Set the matrix mode to modelview set the translation and all the drawing will be drawn at the new position.

Answer 2

You mention you call update from another thread, but OpenGL calls are only valid on the same thread that created the context.

Also you should read about OpenGL transformations. It takes some effort to understand so have patience.

http://glprogramming.com/red/chapter03.html