Set value to uniform int in fragment shader


this should be a stupid problem, as i’ve been setting uniform float and vec2 values without problems, but it seems that i don’t set up the int value correctly…

EDIT: I forgot to mention that i’m working with opengl es (for an iPhone game)

Here is the fragment shader:

#ifdef GL_ES
precision mediump float;

// Texture, coordinates and size
uniform sampler2D u_texture;
varying vec2 v_texCoord;
uniform vec2 textureSize;

// this is the one that i'm trying to set
uniform int lightCount;

struct LightSource
	vec2 position;
	float radius;
	float strength;

uniform LightSource lights[10];

void main()
	float alpha = 1.0;
	vec2 pos = vec2(v_texCoord.x * textureSize.x, v_texCoord.y * textureSize.y);
	// here i try to do 'lightCount' loops. I've set lightCount to 1 from cpp and got terrible performance
        // but if i put a break; at the end of the loop the performance increases a lot, so i assume that
        // lightCount is a very big value (11215121 for example), like i did not set it...

	int i = 0;
	while (i < lightCount)
		LightSource source = lights[i];
		float distance = distance(source.position, pos);
		if (distance < source.radius)
			alpha -= source.strength;
	alpha = max(0.0, alpha);
	gl_FragColor = vec4(texture2D(u_texture, v_texCoord).rgb, alpha);

This is my c++ code:

		// cocos2d-x OpenGl wrapper code has already initialized the shader and all of the following works except the int part
		// get program from cocos2d-x wrapper
		GLuint glProgramID = sprite->getShaderProgram()->getProgram();
		// sets vec2 value correctly
		glUniform2f(glGetUniformLocation(glProgramID, "textureSize"), screen.width, screen.height);
		// this is the part that's not working
		GLint lightCount = 1;
		GLint location = glGetUniformLocation(glProgramID, "lightCount");
		glUniform1i(location, lightCount);
		// overcomplicated code to assign properties to an array of structs
		std::string arrayName = "lights["; 
		std::string lightName;
		for (char c = '0'; c - '0' < lightCount && c <= '9'; c++)
			lightName = arrayName + c + "].";
			std::string fieldName = lightName + "position";
			glUniform2f(glGetUniformLocation(glProgramID, fieldName.c_str()), screen.width / 2, screen.height / 2);
			fieldName = lightName + "radius";
			glUniform1f(glGetUniformLocation(glProgramID, fieldName.c_str()), screen.width / 2);
			fieldName = lightName + "strength";
			glUniform1f(glGetUniformLocation(glProgramID, fieldName.c_str()), 1.0f);
		// don't know if this is necessary or not

I thought maybe there was a problem with the array of structs or with the struct itself, but i can’t see anything out of the ordinary…

Note that if change the lightCount variable in the while for a 1 literal performance increases a lot (like when i put a break statement).

Any idea of how i can see if the lightCount is set correctly?
Anyone has a moment to test if this is working (should get the affected texture with a alpha gap on the middle) and the loop is only looping once?

Thanks for your time

Is your program current at the time you set the uniforms ? Uniforms are not bound to the context, but to the current program object, so you have to make your program current with glUseProgram before you update the uniforms.

i did make a call to glUseProgram using the cocos2d-x wrapper, so i guess that is working correctly.
By now i’m using only one light as i cannot control the number of loops and everything works ok (except that int i guess…)