Passing 2D array into GLES opengl shader

Question

I have a 2D array of floats (in this case it represents a 256 color palette with RGB values)

static float[][] glColorPaletteArray = new float[256][3];

I fill the array and now want to pass it to GLES. How do I pass a 2D array in android? I try

GLES20.glUniform3fv(paletteLoc,256,glColorPaletteArray,0);

but it complains about expecting a 1D array (found float[][] expecting float[]).

The shader is expecting a vec3 uniform, ie

uniform vec3 palette[256];

so I need to keep the 2D array so the RGB components are separate floats.

What is the secret to getting the 2D array passed correctly to the GLES shader so I can then access the RGB values in the shader by using

int red = palette[100].r;

Answer 1

The short answer is: You cannot pass a 2D array to a shader.

In order to pass a 2D array to OpenGL, one has to flatten the array. This is relatively easy and can, eg, be done as follows:

static float[][] glColorPaletteArray = new float[256][3];
static float[] openglArray = new float[256*3];

for (int i = 0; i < 256; i++)
    for (int j = 0; j < 3; j++)
        openglArray[i * 3 + j] = glColorPalletArray[i][j];

But I would suggest that, if possible, you define the array in 1D at first hand.