ShaderArrayIssue.md

##Shader Question ######by Jonathan Bobrow ######@jonathanbobrow

I am trying to make a simple shader program and have all pieces working happily except for 1. The following should be enough of the code to see what the issue is, and I know it must be a simple thing, that I am surely faultering on because of my unfamiliarity with GLSL and perhaps the limitations of C here or in general. Any help is much appreciated.

In short, I am passing an array of values from a depth image (which works perfectly, the values get there happily) tested by accessing singular values in the array. The part where it isn't working, is when instead of calling array[0] or some arbitrary index, I want to call an informed index about where the pixel being evaluated is. The part that won't compile is my accessing of the array... which I think has something to do with requiring a const or something of that nature, but just can't seem to get it.

Thanks in advance! Code below :)

#ifdef GL_ES
precision highp float;
#endif

#define PROCESSING_COLOR_SHADER

uniform float time;
uniform vec2 resolution;
uniform sampler2D ppixels;
uniform float rawDepth[64*48];
uniform vec2 kinectResolution; // currently set to (64,48)

void main( void ) {
	vec2 position = ( gl_FragCoord.xy / resolution.xy );  // normalize frag coordinate
	vec2 pixel = 1./resolution; // useful for looking at neighboring pixels

	// get a corresponding pixel in the kinect resolution
	vec2 kinectPosition = position.xy * kinectResolution.xy;
	// get then index for that pixel in the kinect resolution, to access our 1D array of depth values
	int index = int(kinectPosition.y * kinectResolution.x + kinectPosition.x); <---- ISSUE PART I
	// kinect depth value already normalized for comparison as float (0-1)
	if(rawDepth[index] < 0.5) { <---- ISSUE PART II
	  // do something
	}
	else {
	  // don't do that thing... that thing we discussed earlier... don't do it ,,,mmmorty :)
	}
}

Figured out how to do this without using a 1D array, which it seems can only be accessed with constants (not sure why this makes sense, but I am sure there is a good reason, since people much smarter than I architected GL)

In short, I pass in a texture, then simply look at the same position on the texture. So much simpler!