基本光照模型实现-漫反射

漫反射计算公式

兰伯特模型

$$c_{diffuse} = (\mathtt c_{light} \cdot m_{diffuse})\mathrm {max}(0, \hat {\mathcal n} \cdot \hat {\mathcal l})$$

半兰伯特模型

$$c_{diffuse} = (\mathtt c_{light} \cdot m_{diffuse})(\alpha(\hat {\mathcal n} \cdot \hat {\mathcal l}) + \beta)$$

源码-逐顶点

Shader "Custom/DiffuseVertexLevel" {
    Properties {
        _Diffuse("Diffuse",Color) = (1,1,1,1)
    }
    SubShader {
        Pass{
            Tags { "LightMode"="ForwardBase" }

            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "Lighting.cginc"

            fixed4 _Diffuse;

            struct a2v{
                float4 vertex:POSITION;
                float3 normal:NORMAL;
            };

            struct v2f{
                float4 pos:SV_POSITION;
                fixed3 color:COLOR;
            };

            v2f vert(a2v v){
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);

                fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz;

                fixed3 worldNormal = normalize(mul(v.normal,(float3x3)unity_WorldToObject));

                fixed3 worldLight = normalize(_WorldSpaceLightPos0.xyz);

                fixed3 diffuse = _LightColor0.rgb * _Diffuse.rgb * saturate(dot(worldNormal,worldLight));

                o.color = ambient + diffuse;

                return o;
            }

            fixed4 frag(v2f i):SV_Target{
                return fixed4(i.color,1.0);
            }
            ENDCG
        }
    }
    FallBack "Diffuse"
}

源码-逐像素

Shader "Custom/DiffusePixelLevel" {
    Properties {
        _Diffuse ("Diffuse", Color) = (1, 1, 1, 1)
    }
    SubShader {
        Pass { 
            Tags { "LightMode"="ForwardBase" }

            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag
            #include "Lighting.cginc"

            fixed4 _Diffuse;

            struct a2v{
                float4 vertex:POSITION;
                float3 normal:NORMAL;
            };

            struct v2f{
                float4 pos:SV_POSITION;
                fixed3 worldNormal:TEXCOORD0;
            };

            v2f vert(a2v v){
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.worldNormal = mul(v.normal,(float3x3)unity_WorldToObject);

                return o;
            }

            fixed4 frag(v2f i):SV_Target{
                fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz;

                fixed3 worldNormal = normalize(i.worldNormal);

                fixed3 worldLight = normalize(_WorldSpaceLightPos0.xyz);

                fixed3 diffuse = _LightColor0.rgb * _Diffuse.rgb * saturate(dot(worldNormal,worldLight));

                fixed3 color = ambient + diffuse;

                return fixed4(color,1.0);
            }

            ENDCG
        }
    }
    FallBack "Diffuse"
}

半兰伯特-逐像素

Shader "Custom/DiffuseHalfLambert" {
    Properties {
        _Diffuse ("Diffuse", Color) = (1, 1, 1, 1)
    }
    SubShader {
        Pass { 
            Tags { "LightMode"="ForwardBase" }

            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag
            #include "Lighting.cginc"

            fixed4 _Diffuse;

            struct a2v{
                float4 vertex:POSITION;
                float3 normal:NORMAL;
            };

            struct v2f{
                float4 pos:SV_POSITION;
                fixed3 worldNormal:TEXCOORD0;
            };

            v2f vert(a2v v){
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.worldNormal = mul(v.normal,(float3x3)unity_WorldToObject);

                return o;
            }

            fixed4 frag(v2f i):SV_Target{
                fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz;

                fixed3 worldNormal = normalize(i.worldNormal);

                fixed3 worldLight = normalize(_WorldSpaceLightPos0.xyz);

                fixed3 halfLambert = dot(worldNormal,worldLight) * 0.5 + 0.5;
                fixed3 diffuse = _LightColor0.rgb * _Diffuse.rgb * halfLambert;

                fixed3 color = ambient + diffuse;

                return fixed4(color,1.0);
            }

            ENDCG
        }
    }
    FallBack "Diffuse"
}

效果图