[android-developers] VBO problem using OpenGL ES 2.0 on android 2.2

Hello,

I'm trying to display a simple triangle on my Samsung Spica.
I'm using the following data:

float triangle_vertices[] = {
0.0f, 0.8f,
-0.8f, -0.8f,
0.8f, -0.8f
};

vertex shader:
attribute vec2 vPosition;
void main(void)
{
gl_Position = vec4(vPosition, 0.0, 1.0);
}

fragment shader:
void main()
{
gl_FragColor[0] = gl_FragCoord.x/640.0;
gl_FragColor[1] = gl_FragCoord.y/480.0;
gl_FragColor[2] = 0.5;
}

If I display it without VBO, it will show on the screen:
GLES20.glVertexAttribPointer(
agrPositionHandle, // attribute
2, // number of elements per vertex
GLES20.GL_FLOAT, // the type of each element
false, // take our values as-is
2*Float.SIZE/8, // vertices
//0, // no extra data between each position
triangleVB // FloatBuffer
);
GLES20.glEnableVertexAttribArray(agrPositionHandle);
Utils.displayGLErrorCode(TAG,
"onDrawFrame:glEnableVertexAttribArray");
GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 3);
Utils.displayGLErrorCode(TAG, "onDrawFrame:glDrawArrays");

To use the VBO, I needed to implement the GLES20Fix from this post:
http://stackoverflow.com/questions/8552365/vertex-buffer-objects-vbo-not-working-on-android-2-3-3-using-gles20

Then I replaced the call to GLES20.glVertexAttribPointer() with:
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, agrVboTriangle.get(0));
GLES20Fix.glVertexAttribPointer(
agrPositionHandle, // attribute
2, // number of elements per vertex
GLES20.GL_FLOAT, // the type of each element
false, // take our values as-is
2*Float.SIZE/8, // vertices
0 // offset
);
Utils.displayGLErrorCode(TAG, "onDrawFrame:glVertexAttribPointer");

But in that case, the screen remains blank. And I saw no OpenGL error.

Any hints would be appreciated.

-
Fabien


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