I don't think uniform arrays can be dynamically sized. In your case you should define the array as the maximum number of lights you will process and then use a uniform to control the number of iterations you do on this array. On the CPU side you can set a subset of the lights[] array according to the 'size' variable.

e.g.

#define MAX_LIGHTS 128

uuniform int size;
uniform SceneLights lights[MAX_LIGHTS];

void main()
{
    for(int i = 0; i < size; i++) {
        /* Do Some Calculation */
    }
}

I think (speculate) the likely reason for this is that it would be impossible to determine the location of a uniform if there are variable sized arrays in your uniform list which depend on the value of another uniform.. e.g.

uniform int arraySize;               // offset 0
uniform int myArray[arraySize];      // offset 4
uniform int anotherVar;              // offset ???? 

GLSL would not know were to place anotherVar, because it would need arraySize to be set with a value before it can compute the offset of 'anotherVar'. I suppose the compiler could be clever and re-arrange the order of uniforms to get around this, but this will fail again if you have 2 or more variable sized arrays..

I don't think uniform arrays can be dynamically sized. In your case you should define the array as the maximum number of lights you will process and then use a uniform to control the number of iterations you do on this array. On the CPU side you can set a subset of the lights[] array according to the 'size' variable.

e.g.

#define MAX_LIGHTS 128

uniform int size;
uniform SceneLights lights[MAX_LIGHTS];

void main()
{
    for(int i = 0; i < size; i++) {
        /* Do Some Calculation */
    }
}

I think (speculate) the likely reason for this is that it would be impossible to determine the location of a uniform if there are variable sized arrays in your uniform list which depend on the value of another uniform.. e.g.

uniform int arraySize;               // offset 0
uniform int myArray[arraySize];      // offset 4
uniform int anotherVar;              // offset ???? 

GLSL would not know were to place anotherVar, because it would need arraySize to be set with a value before it can compute the offset of 'anotherVar'. I suppose the compiler could be clever and re-arrange the order of uniforms to get around this, but this will fail again if you have 2 or more variable sized arrays..

I don't think uniform arrays can be dynamically sized. In your case you should define the array as the maximum number of lights you will process and then use a uniform to control the number of iterations you do on this array.

I think (speculate) the likely reason for this is that it would be impossible to determine the location of a uniform if there are variable sized arrays in your uniform list which depend on the value of another uniform.. e.g.

uniform int arraySize;               // offset 0
uniform int myArray[arraySize];      // offset 4
uniform int anotherVar;              // offset ???? 

GLSL would not know were to place anotherVar, because it would need arraySize to be set with a value before it can compute the offset of 'anotherVar'

You could also look at using SSBOs if you need larger buffers than uniforms allow

I don't think uniform arrays can be dynamically sized. In your case you should define the array as the maximum number of lights you will process and then use a uniform to control the number of iterations you do on this array. On the CPU side you can set a subset of the lights[] array according to the 'size' variable.

e.g.

#define MAX_LIGHTS 128

uuniform int size;
uniform SceneLights lights[MAX_LIGHTS];

void main()
{
    for(int i = 0; i < size; i++) {
        /* Do Some Calculation */
    }
}

I think (speculate) the likely reason for this is that it would be impossible to determine the location of a uniform if there are variable sized arrays in your uniform list which depend on the value of another uniform.. e.g.

uniform int arraySize;               // offset 0
uniform int myArray[arraySize];      // offset 4
uniform int anotherVar;              // offset ???? 

GLSL would not know were to place anotherVar, because it would need arraySize to be set with a value before it can compute the offset of 'anotherVar'. I suppose the compiler could be clever and re-arrange the order of uniforms to get around this, but this will fail again if you have 2 or more variable sized arrays..