I implemented a Phong shader in GLSL, but there is a bug.
What you are (supposed) to see down below:
A point light source rotating around the center of the world,
- with a radiance of (0, 100, 0)
A textured quad with kd of (1, 0, 0).
The problem is:
Why is there a a green line to the center of the world instead of a green spot light where the quad is lit? (where the center of the point light source is)
- (Btw in this case there would be only a yellow spot of light, because red + green = yellow)
Vertex Shader:
#version 330
uniform mat4 ModelMatrix, ViewMatrix, ProjectionMatrix;
uniform vec4 wLiPos[5]; // pos of light source
uniform vec3 wEye; // pos of eye
uniform int lightSize; //number of lights
layout(location = 0) in vec3 vtxPos;
layout(location = 1) in vec3 vtxNorm;
layout(location = 2) in vec2 vtxUV;
out vec2 texCoord;
out vec3 wNormal; // normal in world space
out vec3 wView[5]; // view in world space
out vec3 wLight[5]; // light dir in world space
void main() {
gl_Position = ProjectionMatrix * ViewMatrix * ModelMatrix * vec4(vtxPos, 1);
texCoord = vtxUV;
vec4 wPos = ModelMatrix * vec4(vtxPos, 1);
wNormal = (vec4(vtxNorm, 0) * inverse(ModelMatrix)).xyz;
for(int i = 0; i < lightSize; i++) {
wView[i] = wEye * wPos.w - wPos.xyz;
wLight[i] = wLiPos[i].xyz * wPos.w - wPos.xyz * wLiPos[i].w;
}
}
Fragment shader:
#version 330
uniform sampler2D samplerUnit;
uniform vec3 kd, ks, ka; // diffuse, specular, ambient ref
uniform vec3 La, Le[5]; // ambient and point source rad
uniform float shininess; // shininess for specular ref
uniform int lightSize;
in vec2 texCoord;
in vec3 wNormal; // interpolated world sp normal
in vec3 wView[5]; // interpolated world sp view
in vec3 wLight[5]; // interpolated world sp illum dir
layout(location = 0) out vec4 fragmentColor;
void main() {
vec3 color = vec3(0, 0, 0);
for(int i = 0; i < lightSize; i++) {
vec3 N = normalize(wNormal);
vec3 V = normalize(wView[i]);
vec3 L = normalize(wLight[i]);
vec3 H = normalize(L + V);
float cost = max(dot(N,L), 0);
float cosd = max(dot(N,H), 0);
color += ka * La + (kd * cost + (ks * pow(cosd, shininess)) * Le[i]) / pow(length(wLight[i]), 2);
}
vec3 gamma = vec3(1.0/2.2);
fragmentColor = vec4(pow(color * vec3(texture2D(samplerUnit, texCoord)), gamma), 1);
}
