#ifndef HERO_CUTOUT_INCLUDED
#define HERO_CUTOUT_INCLUDED

// World-space "hero cutout": clips occluder fragments that lie inside a CONE running from the camera
// (apex) to the player (target). Everything BETWEEN the camera and the target within the cone is
// punched see-through; geometry well behind the target stays solid - so a wall the player stands in
// front of still renders completely normally. The "between vs. behind" split is purely geometric
// (position along the camera->target axis), not a depth-buffer bias.
//
// That far split is FEATHERED on BOTH sides, never a hard plane: the cut fades out smoothly across a
// band of +/- 'depthFeather' metres AROUND the target. So an occluder that crosses the player's depth
// (a shelf board or wall running away from the camera) keeps fading just behind the player instead of
// snapping to solid - no hard straight cut line where a depth plane would slice the surface. Only
// geometry beyond that band (more than depthFeather behind the target) stays fully solid.
//
// Why a cone and not a cylinder: the cone's radius grows linearly with distance from the camera
// (radius = paramRadius * along/len), so its *screen-space* footprint is constant regardless of how
// far the occluder sits from the camera. A constant-world-radius cylinder would project bigger near
// the lens and smaller near the target - a distorted hole. paramRadius is therefore the radius at the
// target plane (metres); the cone tapers to 0 at the camera apex.
//
// Driven every frame by HeroCutout.cs (Shader.SetGlobalVector). These globals live OUTSIDE
// UnityPerMaterial, so the SRP Batcher is unaffected. When disabled (_HeroCutoutTarget.w < 0.5, also
// the zero-initialised default) ApplyHeroCutout early-outs and the shader renders exactly like URP/Lit.
//   _HeroCutoutTarget : xyz = player/target world position, w = enabled (0/1)
//   _HeroCutoutParams : x = cone radius at the target plane (m), y = edge feather at the target plane (m),
//                       z = depth feather: half-width (m) of the soft fade band straddling the target
float4 _HeroCutoutTarget;
float4 _HeroCutoutParams;

// Interleaved-gradient noise -> screen-door dither, gives the cone wall a soft edge with no extra
// textures or includes.
float HeroCutoutDither(float2 positionSS)
{
    return frac(52.9829189 * frac(dot(positionSS, float2(0.06711056, 0.00583715))));
}

void ApplyHeroCutout(float4 positionCS)
{
    if (_HeroCutoutTarget.w < 0.5)
        return;

    // Reconstruct this fragment's world position from screen UV + device depth.
    float2 screenUV = GetNormalizedScreenSpaceUV(positionCS);
    float3 posWS = ComputeWorldSpacePosition(screenUV, positionCS.z, UNITY_MATRIX_I_VP);

    float3 camPos = _WorldSpaceCameraPos.xyz;
    float3 axis = _HeroCutoutTarget.xyz - camPos;
    float len = length(axis);
    if (len < 1e-4)
        return;
    float3 dir = axis / len;

    // Distance along the camera->target axis (metres from the camera).
    float along = dot(posWS - camPos, dir);
    float depthFeather = max(_HeroCutoutParams.z, 1e-4);
    if (along <= 0.0 || along >= len + depthFeather) // behind the camera, or well behind the target -> solid
        return;

    // Perpendicular distance to the axis -> the cone test.
    float3 closest = camPos + dir * along;
    float radial = length(posWS - closest);

    // Cone: radius scales with distance from the camera (apex), so the on-screen hole stays the same
    // size at every occluder depth. t in (0,1]: 0 at the camera, 1 at the target plane.
    float t = along / len;
    float radius = _HeroCutoutParams.x * t;
    float feather = max(_HeroCutoutParams.y * t, 1e-4);
    float radialCut = 1.0 - smoothstep(radius - feather, radius, radial); // 1 inside the cone, 0 outside

    // Soft depth cap instead of a hard plane at the target: the cut fades out across a band straddling
    // the target - full strength up to (len - depthFeather), gone by (len + depthFeather). So an occluder
    // crossing the player's depth keeps fading just behind them rather than showing a hard straight edge.
    float axialCut = 1.0 - smoothstep(len - depthFeather, len + depthFeather, along);

    float cut = radialCut * axialCut;
    clip(HeroCutoutDither(positionCS.xy) - cut);
}
#endif