GPU20PBRTemplate.shader

// Aaron Lanterman, July 20, 2020
// Cobbled together from numerous sources (including Catlike Coding & Unity docs)
Shader "GPU19/PBRTemplate" {
	Properties {
        _Placeholder ("Placeholder Slider", Range (0, 1)) = 0.5
	}

    SubShader {
        Tags { "LightMode" = "ForwardAdd" } // Use for point light
        // Tags { "LightMode" = "ForwardBase" } // Use for directional light
    	 
        Pass {
            HLSLPROGRAM

            #pragma vertex VertPBRTemplate
            #pragma fragment FragPBRTemplate
            #include "UnityCG.cginc"

            sampler2D _BaseTex;	
            float4 _BaseTex_ST;

            float4 _LightColor0; // Unity fills for us
            float _Placeholder;

            struct a2v {    			
                float4 positionOS: POSITION;
                float3 normalOS: NORMAL;
                float2 uv: TEXCOORD0;	
            };
           	
            struct v2f {				
                float4 sv: SV_POSITION;
                float2 uv: TEXCOORD0;   
                float3 positionWS: TEXCOORD1;     
                float3 normalWS: TEXCOORD2;  
            };
 
            v2f VertPBRTemplate(a2v input) {
                v2f output;           

                float4 positionWS = mul(unity_ObjectToWorld, float4(input.positionOS.xyz, 1.0));
                output.sv = mul(unity_MatrixVP, positionWS);
                output.positionWS = positionWS.xyz;
               
                // To transform normals, we want to use the inverse transpose of upper left 3x3
                // Putting input.n in first argument is like doing trans((float3x3)_World2Object) * input.n;
                output.normalWS = normalize(mul(input.normalOS, (float3x3) unity_WorldToObject));
                output.uv = TRANSFORM_TEX(input.uv, _BaseTex);
                return output;
            }

            float4 FragPBRTemplate(v2f input) : COLOR {
                // Unity light position convention is:
                // w = 0, directional light, with x y z pointing in opposite of light direction 
                // w = 1, point light, with x y z indicating position coordinates
                float3 unNormLightDir = _WorldSpaceLightPos0.xyz - input.positionWS * _WorldSpaceLightPos0.w;
                float3 lightDir = normalize(unNormLightDir);
                // renormalizing because the GPU's interpolator doesn't know this is a unit vector
                float3 n = normalize(input.normalWS);

                float3 viewDir = normalize(_WorldSpaceCameraPos - input.positionWS);   
                float3 halfVector = normalize(viewDir + lightDir);  

                float3 output = float3(1,1,1); // A placeholder, replace with your own code
                return(float4(output,1));
            }

            ENDHLSL
        }
    }
}