I am doing my first steps in shader coding using GLSL. For a start I wanted to create a lighting algorithm, so I browsed the internet and found some fairly simple examples. To suit my need I only changed the lights by adding my own custom ones, as uniform variables. Here the code:
// The shader is creating the light effects on a sphere
// from several light sources.
uniform vec3 Sphere_Position;
uniform int Light_Counter;
uniform vec3 Light_Position;
uniform vec3 Light_Color ;
uniform float Light_Factor ;
// Main function
gl_TexCoord = gl_MultiTexCoord0;
gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
gl_FrontColor = gl_Color;
for(int i = 0; i < Light_Counter; i ++)
vec3 Light_Direction = -normalize(gl_Position.xyz - Light_Position[i].xyz);
vec3 Vertex_Normal = normalize(gl_NormalMatrix * gl_Normal);
float Dot_Product = max(dot(Vertex_Normal, Light_Direction), 0.0);
float Light_Distance = length(gl_Position.xyz - Light_Position[i].xyz);
float Final_Factor = (Dot_Product * Light_Factor[i]) / (Light_Distance * Light_Distance);
gl_FrontColor.xyz = gl_FrontColor.xyz * Light_Color[i].xyz * Final_Factor;
Now as the title suggest, when rendering, this produces a nice light/shadow effect, except for a small black circle zone in the middle of the sphere… Sounds to me like a very basic geometry principle, but I can’t figure it out!
Any help would be very much appreciated!
EDIT: I forgot to mention that to first keep it simple, I am testing with a single light. So the ‘for’ loop can be neglect for the moment!