GLSL像素的方向光。
vertex shader的程式碼：
varying vec4 diffuse,ambient;
varying vec3 normal,lightDir,halfVector;
void main()
{
/* first transform the normal into eye space and normalize the result */
normal = normalize(gl_NormalMatrix * gl_Normal);
/* now normalize the light's direction. Note that according to the
OpenGL specification, the light is stored in eye space. Also since
we're talking about a directional light, the position field is actually
direction */
lightDir = normalize(vec3(gl_LightSource[0].position));
/* Normalize the halfVector to pass it to the fragment shader */
halfVector = normalize(gl_LightSource[0].halfVector.xyz);
/* Compute the diffuse, ambient and globalAmbient terms */
diffuse = gl_FrontMaterial.diffuse * gl_LightSource[0].diffuse;
ambient = gl_FrontMaterial.ambient * gl_LightSource[0].ambient;
ambient += gl_LightModel.ambient * gl_FrontMaterial.ambient;
gl_Position = ftransform();
}
fragment shader的程式碼：
varying vec4 diffuse,ambient;
varying vec3 normal,lightDir,halfVector;
void main()
{
vec3 n,halfV,viewV,ldir;
float NdotL,NdotHV;
vec4 color = ambient;
/* a fragment shader can't write a verying variable, hence we need
a new variable to store the normalized interpolated normal */
n = normalize(normal);
/* compute the dot product between normal and ldir */
NdotL = max(dot(n,lightDir),0.0);
if (NdotL > 0.0) {
halfV = normalize(halfVector);
NdotHV = max(dot(n,halfV),0.0);
color += gl_FrontMaterial.specular * gl_LightSource[0].specular * pow(NdotHV,gl_FrontMaterial.shininess);
color += diffuse * NdotL;
}
gl_FragColor = color;
}
執行結果：
逍遙文工作室 
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