交集著色器

著色器，用來實作與相關聯周框磁片區交集 (周框方塊) 的光線自訂交集基本類型。

交集著色器無法存取光線承載，但會透過對 ReportHit的呼叫來定義每個點擊的交集屬性。 如果設定了 ray 旗標RAY_FLAG_ACCEPT_FIRST_HIT_\AND_\END_SEARCH，或從任何點擊著色器呼叫AcceptHitAndEndSearch，則 ReportHit的處理可能會提早停止交集著色器。 否則，如果已接受點擊，則傳回 true;如果點擊遭到拒絕，則會傳回 false。 這表示如果存在，任何點擊著色器都必須執行，才能有條件地將控制項傳回交集著色器。

著色器類型屬性

[shader("intersection")]

範例

struct CustomPrimitiveDef { ... };
struct MyAttributes { ... };
struct CustomIntersectionIterator {...};
void InitCustomIntersectionIterator(CustomIntersectionIterator it) {...}
bool IntersectCustomPrimitiveFrontToBack(
    CustomPrimitiveDef prim,
    inout CustomIntersectionIterator it,
    float3 origin, float3 dir,
    float rayTMin, inout float curT,
    out MyAttributes attr);

[shader("intersection")]
void intersection_main()
{
    float THit = RayTCurrent();
    MyAttributes attr;
    CustomIntersectionIterator it;
    InitCustomIntersectionIterator(it); 
    while(IntersectCustomPrimitiveFrontToBack(
            CustomPrimitiveDefinitions[LocalConstants.PrimitiveIndex],
            it, ObjectRayOrigin(), ObjectRayDirection(), 
            RayTMin(), THit, attr))
    {
        // Exit on the first hit.  Note that if the ray has
        // RAY_FLAG_ACCEPT_FIRST_HIT_AND_END_SEARCH or an
        // anyhit shader is used and calls AcceptHitAndEndSearch(),
        // that would also fully exit this intersection shader (making
        // the “break” below moot in that case).        
        if (ReportHit(THit, /*hitKind*/ 0, attr) && (RayFlags() &  RAY_FLAG_FORCE_OPAQUE))
            break;
    }
}