opengl - 聚光灯的着色器

Question

我怎样才能让这个着色器在聚光灯上有一个平滑的边缘而不是一个坚硬的边缘？此外，着色器必须处理 GL_SPOT_CUTOFF 的变量值。请注意，并非所有灯光都是聚光灯——GL_LIGHT0 是点光源。

varying vec3 N;
varying vec3 v;
#define MAX_LIGHTS 2 
void main (void)  
{  
    vec4 finalColour;
    float spotEffect;

    for (int i=0; i<MAX_LIGHTS; i++)
    {
        vec3 L = normalize(gl_LightSource[i].position.xyz - v);   
        vec3 E = normalize(-v);
        vec3 R = normalize(-reflect(L,N));

        spotEffect = dot(normalize(gl_LightSource[i].spotDirection), 
                         normalize(-L));
        if (spotEffect > gl_LightSource[i].spotCosCutoff) {
            vec4 Iamb = gl_FrontLightProduct[i].ambient;    
            vec4 Idiff = gl_FrontLightProduct[i].diffuse * max(dot(N,L), 0.0);
            Idiff = clamp(Idiff, 0.0, 1.0);     
            vec4 Ispec = gl_FrontLightProduct[i].specular 
                         * pow(max(dot(R,E),0.0),0.3*gl_FrontMaterial.shininess);
            Ispec = clamp(Ispec, 0.0, 1.0);
            finalColour += Iamb + Idiff + Ispec;
        }
    }
    gl_FragColor = gl_FrontLightModelProduct.sceneColor + finalColour;

}

场景是这样的：

Answer 1

这个来自http://www.ozone3d.net/tutorials/glsl_lighting_phong_p3.php的着色器会为您所追求的聚光灯产生柔和的边缘。

[Pixel_Shader]

varying vec3 normal, lightDir, eyeVec;

const float cos_outer_cone_angle = 0.8; // 36 degrees

void main (void)
{
    vec4 final_color =
    (gl_FrontLightModelProduct.sceneColor * gl_FrontMaterial.ambient) +
    (gl_LightSource[0].ambient * gl_FrontMaterial.ambient);

    vec3 L = normalize(lightDir);
    vec3 D = normalize(gl_LightSource[0].spotDirection);

    float cos_cur_angle = dot(-L, D);

    float cos_inner_cone_angle = gl_LightSource[0].spotCosCutoff;

    float cos_inner_minus_outer_angle = 
          cos_inner_cone_angle - cos_outer_cone_angle;

    //****************************************************
    // Don't need dynamic branching at all, precompute 
    // falloff(i will call it spot)
    float spot = 0.0;
    spot = clamp((cos_cur_angle - cos_outer_cone_angle) / 
           cos_inner_minus_outer_angle, 0.0, 1.0);
    //****************************************************

    vec3 N = normalize(normal);

    float lambertTerm = max( dot(N,L), 0.0);
    if(lambertTerm > 0.0)
    {
        final_color += gl_LightSource[0].diffuse *
            gl_FrontMaterial.diffuse *
            lambertTerm * spot;

        vec3 E = normalize(eyeVec);
        vec3 R = reflect(-L, N);

        float specular = pow( max(dot(R, E), 0.0),
            gl_FrontMaterial.shininess );

        final_color += gl_LightSource[0].specular *
            gl_FrontMaterial.specular *
            specular * spot;
    }
    gl_FragColor = final_color;