Passing vectors from Vertex to Fragment

General Discussions
#1

I’m trying to find a way to implement ray-casing completely by GLSL, and I was thinking of maybe getting the vertices from the vertex shader into the fragment shader. Then using some kind of algorithm for calculating a shadow.

Heres my shaders;

light.fs;

#version 150

uniform vec2 lightLocation;
uniform vec3 lightColor;
uniform vec3 ambientLight;

vec3 baseColor = vec3(1.0, 1.0, 1.0);

void main() { 
	vec4 light = vec4(ambientLight, 1);
	vec4 color = vec4(baseColor,1);

	float distance = length(lightLocation - gl_FragCoord.xy);
	float attenuation = 1.0 / distance;
	vec4 lColor = vec4(attenuation, attenuation, attenuation, pow(attenuation, 3.0)) * vec4(lightColor, 1);
	color += lColor;

	gl_FragColor = color * light;
}

light.vs

#version 150

void main(){
   	gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
}