OptiX 6.0.0 is broken on driver 591.44

Gaming and Visualization Technologies Visualization OptiX
16

I’m now having some extremely weird bug where my lights receive wrong shadows from other lights… it’s random, seemingly dependent on shader/geometry complexity and the number of samples, though it looks the same as long as the input data doesn’t change. I triple-checked my structures, payload usage, etc, but I can’t figure it out. The code worked fine in OptiX 6. Main part of raygen looks roughly like this:

for (uint i = 0; i < num_lights; i++)
{
	LocalLight lightData = localLights[i];
	ColorData localColorData;
	InitColorData(localColorData);
	if (LightPoint(lightData, pos, normal, inputData, localColorData)) // compute unshadowed lighting
	{
		// Generate shadows
		float shadow = 0;
		bool shadowmaskFalloff = false;
		float lightRadius = lightData.rangeParams.x;
		float3 lightPos = lightData.position;
		int lightSamples = lightData.lightSamples;
		for (int j = 0; j < lightSamples; ++j)
		{

			float3 randomPos = GenRandomPos() * lightRadius + lightPos;

			float3 nndir = normalize(randomPos - worldPos);
			Ray occRay = make_Ray(rayOrigin, nndir, 1, epsilonFloatT(rayOrigin, nndir), length(randomPos - worldPos));
			RayData occData;
			occData.result = 1.0f;

			unsigned int _payloadX = __float_as_uint(occData.result);

			optixTrace( (OptixPayloadTypeID)0, // there is only 1
						root,
						occRay.origin,
						occRay.direction,
						occRay.tmin,
						occRay.tmax,
						0.0f,
						(OptixVisibilityMask)1,
						OPTIX_RAY_FLAG_NONE,
						occRay.ray_type,
						2, // there are 2 ray types total
						occRay.ray_type,
						_payloadX);

			occData.result = __uint_as_float(_payloadX);

			shadow += occData.result;
		}
		shadow /= lightSamples;

		AddColorData(colorData, localColorData, shadow);
	}
}

And the anyhit function is basically:

if (triAlpha == 0.0f)
{
	optixIgnoreIntersection();
	return;
}

optixSetPayload_0( __float_as_uint(0.0f) );
optixTerminateRay();

What happens is that suddenly light 2 may start using shadow from light 1 and so on - if I create another light, it shuffles differently again:

image
image393×203 25.1 KB

(The green spotlight is wrongly using the colored point light’s shadow)

It feels as if the optixTrace / hit programs are not synchronous (??) and I’m not getting the correct payload…

The payloads are configured like this:

// Only one float4 payload type for now
const int numPayloadValues = 4;
unsigned int basePayloadFlags = OPTIX_PAYLOAD_SEMANTICS_TRACE_CALLER_READ_WRITE | 
								OPTIX_PAYLOAD_SEMANTICS_CH_READ_WRITE | 
								OPTIX_PAYLOAD_SEMANTICS_AH_READ_WRITE | 
								OPTIX_PAYLOAD_SEMANTICS_MS_WRITE | 
								OPTIX_PAYLOAD_SEMANTICS_IS_NONE;
const unsigned int payloadSemantics[numPayloadValues] =
{
	basePayloadFlags,
	basePayloadFlags,
	basePayloadFlags,
	basePayloadFlags
};
OptixPayloadType payloadType = {};
payloadType.numPayloadValues = numPayloadValues;
payloadType.payloadSemantics = payloadSemantics;
OptixModuleCompileOptions moduleCompileOptions = {};
moduleCompileOptions.numPayloadTypes = 1;
moduleCompileOptions.payloadTypes    = &payloadType;

(Basically everything is read-write for now except for IS which I don’t have and MS which never reads)

…I’m only using 1 value out of the declared 4 here. Just in case, I tried forcing numPayloadValues to 1 and it didn’t help.

…unrolling the samples look actually makes it work, but I don’t want to unroll it…