Unity中写GLSL（十六）—— 菲涅尔反射

最新推荐文章于 2025-06-09 14:37:58 发布

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本文介绍了一种使用Unity的GLSL编程实现轮廓高光效果的方法。通过顶点和片段着色器代码，实现了光照模型中高光部分的增强显示，尤其是在模型轮廓处的效果更加明显。

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参考了wiki：https://en.wikibooks.org/wiki/GLSL_Programming/Unity/Specular_Highlights_at_Silhouettes

先上图：不过看不太出什么区别
这里写图片描述

然后是代码:

Shader "Custom/ShaderExample17"
{
    Properties
    {
        _Color ("Diffuse Material Color", Color) = (1,1,1,1)
        _SpecColor ("Specular Material Color", Color) = (1,1,1,1)
        _Shininess ("Shininess", Float) = 10
        _PowerFactor ("Power", Float) = 5
    }

    SubShader
    {
        Pass
        {
            Tags { "LightMode" = "ForwardBase" }

            GLSLPROGRAM

            uniform vec4 _Color;
            uniform vec4 _SpecColor;
            uniform float _Shininess;
            uniform float _PowerFactor;

            uniform vec3 _WorldSpaceCameraPos;
            uniform mat4 _Object2World;
            uniform mat4 _World2Object;
            uniform vec4 _WorldSpaceLightPos0;
            uniform vec4 _LightColor0;

            #ifdef VERTEX
            //顶点着色器

            out vec4 position;
            out vec3 worldNormalDirection;

            void main()
            {
                mat4 modelMatrix = _Object2World;
                mat4 modelMatrixInverse = _World2Object;

                position = modelMatrix * gl_Vertex;
                worldNormalDirection = normalize(vec3(vec4(gl_Normal, 0.0) * modelMatrixInverse));

                gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
            }

            #endif

            #ifdef FRAGMENT
            //片元着色器

            in vec4 position;
            in vec3 worldNormalDirection;

            void main()
            {
                vec3 normalDirection = normalize(worldNormalDirection);
                vec3 viewDirection = normalize(_WorldSpaceCameraPos - vec3(position));
                vec3 lightDirection;
                float attenuation;

                if (0.0 == _WorldSpaceLightPos0.w)  //方向光
                {
                    attenuation = 1.0;
                    lightDirection = normalize(vec3(_WorldSpaceLightPos0));
                }
                else    //点光源或聚光灯
                {
                    vec3 vertexToLightSource = vec3(_WorldSpaceLightPos0 - position);
                    float ddistance = length(vertexToLightSource);
                    attenuation = 1.0 / ddistance;
                    lightDirection = normalize(vertexToLightSource);
                }

                //ambient
                vec3 ambientLighting = vec3(gl_LightModel.ambient) * vec3(_Color);
                //diffuse
                vec3 diffuseReflection = attenuation * vec3(_LightColor0) * vec3(_Color)
                                        * max(0.0, dot(normalDirection, lightDirection));

                vec3 specularReflection;
                if (dot(normalDirection, lightDirection) < 0.0)
                {
                    specularReflection = vec3(0.0, 0.0, 0.0);
                }
                else
                {
                    vec3 halfwayDirection = normalize(lightDirection + viewDirection);
                    float w = pow(1.0 - max(0.0, dot(halfwayDirection, viewDirection)), _PowerFactor);
                    specularReflection = attenuation * vec3(_LightColor0)
                                         * mix(vec3(_SpecColor), vec3(1.0), w)
                                         * pow(max(0.0, dot(reflect(-lightDirection, normalDirection), viewDirection)), _Shininess);
                }

                gl_FragColor = vec4(ambientLighting + diffuseReflection + specularReflection, 1.0);
            }

            #endif

            ENDGLSL
        }
    }
}