平行光漫反射模型

即Lambert模型，更多关于Lambert的信息请google.

参考：http://www.lighthouse3d.com/tutorials/glsl-tutorial/directional-lights-i/

例子的源代码：http://download.csdn.net/detail/netrookie/4306606

glsl vertex shader:

struct MaterialParameters 
{
    vec4 emission;
    vec4 ambient;
    vec4 diffuse;
    vec4 specular;
    float shininess;
};

struct LightSourceParameters 
{
    vec4 ambient;
    vec4 diffuse;
    vec4 specular;
    vec4 position;
    vec4 halfVector;
    vec3 spotDirection;
    float spotExponent;
    float spotCutoff;
    float spotCosCutoff;
    float constantAttenuation;
    float linearAttenuation;
    float quadraticAttenuation;
};

uniform mat4 m_mvp_mat;
uniform mat4 m_model_it;

uniform MaterialParameters m_material_attr;
uniform LightSourceParameters m_light_attr;

attribute vec4 m_position;
attribute vec3 m_normal;

varying vec4 m_out_color;

void main()
{
    vec3 normal, light_dir;
    float indensity;
    vec4 diffuse;

    light_dir = normalize(vec3(m_light_attr.position));
    normal = normalize(vec3(m_model_it * vec4(m_normal, 0.0)));

    indensity = max(dot(normal, light_dir), 0.0);

    diffuse = m_material_attr.diffuse * m_light_attr.diffuse;
    m_out_color = indensity * diffuse;

    gl_Position = m_mvp_mat * m_position;
}

glsl frag shader src:

varying vec4 m_out_color;

void main()
{
    gl_FragColor = m_out_color;
}

截图：