Convert multidimensional array to Floatbuffer and then OpenGL Texture to be used in shader in a batch

Question

In this question the opposite is attempted of the Buffer conversion. Here I have a multi-dimensional array and would like to wrap a buffer around it. I have tried the following without any success:

import java.nio.FloatBuffer;

public class Main
{
    private static final int dataSize = 500;
    private static final float[][] data = new float[dataSize][dataSize];
    public static void main(String[] args) {
        for (int i = 0; i < 500; i++) {
            for (int j = 0; j <500; j++) {
                data[i][j] = i - j; /* to test negative numbers */
            }
        }
        FloatBuffer dataBuf = FloatBuffer.allocate(dataSize * dataSize);
        for(int i = 0; i< data.length; ++i){
            dataBuf.put(data[i], 0, dataSize);
        }
    }
}

The example compiles just fine, Should that sufficiently hold the contents of the array? Is this usage sufficient to handle openGL Textures inside LibGDX?

        IntBuffer numberTexture = IntBuffer.allocate(1);
        dataBuf.position(0);
        Gdx.gl30.glGenTextures(1, numberTexture);
        Gdx.gl30.glBindTexture(GL30.GL_TEXTURE_2D, numberTexture.get());
        Gdx.gl30.glTexParameteri(GL30.GL_TEXTURE_2D, GL30.GL_TEXTURE_MIN_FILTER, GL30.GL_NEAREST);
        Gdx.gl30.glTexParameteri(GL30.GL_TEXTURE_2D, GL30.GL_TEXTURE_MAG_FILTER, GL30.GL_LINEAR);
        Gdx.gl30.glTexImage2D(
            GL30.GL_TEXTURE_2D, 0, GL30.GL_RGBA32F,
            width, height, 0, GL30.GL_RGBA, GL30.GL_FLOAT, dataBuf
        );
        Gdx.gl30.glGenerateMipmap(GL30.GL_TEXTURE_2D);

score 0 · Answer 1 · answered Apr 27 '21 at 13:21

Some adaptations are needed for the above code because

It doesn't resemble the textures format
It's not a direct buffer

import java.nio.FloatBuffer;

public class Main
{
    private static final int dataSize = 500;
    private static final float[][][] data = new float[dataSize][dataSize][4]; /* for RGBA */
    public static void main(String[] args) {
        for (int i = 0; i < 500; i++) {
            for (int j = 0; j <500; j++) {
                data[i][j][0] = i - j; /* to test negative numbers */
                data[i][j][1] = i - j;
                data[i][j][2] = i - j;
                data[i][j][3] = i - j;
            }
        }
                                        /* Float Byte size * RGBA * width * height */
        FloatBuffer dataBuf = ByteBuffer.allocateDirect( 4 * 4 * dataSize * dataSize)
             .asFloatBuffer();
        for(int i = 0; i< data.length; ++i){
            for (int j = 0; j < data[i].length; j++) {
                dataBuf.put(data[i][j],0, 4);
            }
        }
        dataBuf.position(0); /* reset the caret position to the beginning of the array */
    }
}

After the changes, the data array can be succesffully used as a texture buffer.

Convert multidimensional array to Floatbuffer and then OpenGL Texture to be used in shader in a batch

1 Answers1