CodeWalker/CodeWalker.Shaders/LightVS.hlsl

#include "Common.hlsli"

//currently unused - TODO: implement individual HD lights here



struct LODLight
{
    float3 Position;
    uint Colour;
    float3 Direction;
    uint TimeAndStateFlags;
    float4 TangentX;
    float4 TangentY;
    float Falloff;
    float FalloffExponent;
    float InnerAngle; //for cone
    float OuterAngleOrCapExt; //outer angle for cone, cap extent for capsule
};

struct VS_Output
{
    float4 Pos : SV_POSITION;
    float4 Screen : TEXCOORD0;
    uint IID : SV_INSTANCEID;
};


cbuffer VSLightVars : register(b0)
{
    float4x4 ViewProj;
    float4 CameraPos;
    uint LightType; //0=directional, 1=Point, 2=Spot, 4=Capsule
    uint IsLOD; //useful or not?
    uint Pad0;
    uint Pad1;
}

StructuredBuffer<LODLight> LODLights : register(t0);


VS_Output main(float4 ipos : POSITION, uint iid : SV_InstanceID)
{
    float3 opos = 0;
    if (LightType > 0)
    {
        LODLight lodlight = LODLights[iid];
        float extent = lodlight.Falloff;
        
        if (LightType == 1)//point (sphere)
        {
            opos = ipos.xyz * extent;
        }
        else if (LightType == 2)//spot (cone)
        {
            float arads = lodlight.OuterAngleOrCapExt * 0.01745329 * 0.5;  // deg -> rad
            float3 cpos = ipos.xyz * (tan(arads) * extent);
            cpos.y += ipos.w * extent;
            opos = (cpos.x * lodlight.TangentX.xyz) + (cpos.y * lodlight.Direction.xyz) + (cpos.z * lodlight.TangentY.xyz);
        }
        else if (LightType == 4)//capsule
        {
            float3 cpos = ipos.xyz * extent;
            cpos.y += (ipos.w*2-1) * lodlight.OuterAngleOrCapExt * 0.1;
            opos = (cpos.x * lodlight.TangentX.xyz) + (cpos.y * lodlight.Direction.xyz) + (cpos.z * lodlight.TangentY.xyz);
        }
        opos += (lodlight.Position - CameraPos.xyz);
    }
    else
    {
        opos = ipos.xyz;
    }
    float4 spos = mul(float4(opos, 1), ViewProj);
    VS_Output output;
    output.Pos = spos;
    output.Screen = spos;
    output.IID = iid;
    return output;
}