Create texture from byte array in OpenGL, Android

Question

I am trying to display a byte array in an OpenGL GLSurfaceView.

So I have a GLRendererclass implementing Renderer and a method onSurfaceCreated

byte[] data = new byte[512*512];
            for (int i = 0; i < 512*512; i++) {
                data[i] = 100;
            }
            ByteBuffer buffer = ByteBuffer.allocateDirect(512*512);
            buffer.put(data);
            buffer.position(0);

            GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_RGBA, 512, 512, 0,
                    GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, buffer);

But nothing is displayed on the screen. FYI, there is no special code in onSurfaceChanged and onDrawFrame method.

You need 4 bytes of data per pixel if you're using unsigned byte RGBA format. Also what do you mean there is no special code in onDrawFrame? How do you bind the texture? — pleluron
– pleluron, Commented Sep 13, 2016 at 9:53
Use the GL_RED color format then, and go back to 1 byte per pixel. — pleluron
– pleluron, Commented Sep 13, 2016 at 12:36
@pleluron thank you for your response, it worked. Could you post the answer ? — epsilones
– epsilones, Commented Sep 13, 2016 at 12:58

pleluron · Accepted Answer · 2016-09-13 13:08:52Z

1

The format and data size don't match. GL_RGBA takes up 4*sizeof(type) per texel so you need to scale the buffer accordingly. However, if you only want a single channel texture, use GL_RED instead.

answered Sep 13, 2016 at 13:08

pleluron

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