Differential D13361 Diff 45286 intern/cycles/kernel/integrator/shade_volume.h

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intern/cycles/kernel/integrator/shade_volume.h

Show First 20 Lines • Show All 253 Lines • ▼ Show 20 Lines	ccl_device void volume_shadow_heterogeneous(KernelGlobals kg,
}		}

*throughput = tp;		*throughput = tp;
}		}

/* Equi-angular sampling as in:		/* Equi-angular sampling as in:
* "Importance Sampling Techniques for Path Tracing in Participating Media" */		* "Importance Sampling Techniques for Path Tracing in Participating Media" */

		/* Below this pdf we ignore samples, as they tend to lead to very long distances.
		* This can cause performance issues with BVH traversal in OptiX, leading it to
		* traverse many nodes. Since these contribute very little to the image, just ignore
		* those samples. */
		# define VOLUME_SAMPLE_PDF_CUTOFF 1e-8f

ccl_device float volume_equiangular_sample(ccl_private const Ray *ccl_restrict ray,		ccl_device float volume_equiangular_sample(ccl_private const Ray *ccl_restrict ray,
const float3 light_P,		const float3 light_P,
const float xi,		const float xi,
ccl_private float *pdf)		ccl_private float *pdf)
{		{
const float t = ray->t;		const float t = ray->t;
const float delta = dot((light_P - ray->P), ray->D);		const float delta = dot((light_P - ray->P), ray->D);
const float D = safe_sqrtf(len_squared(light_P - ray->P) - delta * delta);		const float D = safe_sqrtf(len_squared(light_P - ray->P) - delta * delta);
▲ Show 20 Lines • Show All 158 Lines • ▼ Show 20 Lines	ccl_device_forceinline void volume_integrate_step_scattering(
* model with balance heuristic for the channels. */		* model with balance heuristic for the channels. */
const float3 albedo = safe_divide_color(coeff.sigma_s, coeff.sigma_t);		const float3 albedo = safe_divide_color(coeff.sigma_s, coeff.sigma_t);
float3 channel_pdf;		float3 channel_pdf;
const int channel = volume_sample_channel(		const int channel = volume_sample_channel(
albedo, result.indirect_throughput, vstate.rphase, &channel_pdf);		albedo, result.indirect_throughput, vstate.rphase, &channel_pdf);

/* Equiangular sampling for direct lighting. */		/* Equiangular sampling for direct lighting. */
if (vstate.direct_sample_method == VOLUME_SAMPLE_EQUIANGULAR && !result.direct_scatter) {		if (vstate.direct_sample_method == VOLUME_SAMPLE_EQUIANGULAR && !result.direct_scatter) {
if (result.direct_t >= vstate.start_t && result.direct_t <= vstate.end_t) {		if (result.direct_t >= vstate.start_t && result.direct_t <= vstate.end_t &&
		vstate.equiangular_pdf > VOLUME_SAMPLE_PDF_CUTOFF) {
const float new_dt = result.direct_t - vstate.start_t;		const float new_dt = result.direct_t - vstate.start_t;
const float3 new_transmittance = volume_color_transmittance(coeff.sigma_t, new_dt);		const float3 new_transmittance = volume_color_transmittance(coeff.sigma_t, new_dt);

result.direct_scatter = true;		result.direct_scatter = true;
result.direct_throughput = coeff.sigma_s new_transmittance / vstate.equiangular_pdf;		result.direct_throughput = coeff.sigma_s new_transmittance / vstate.equiangular_pdf;
shader_copy_volume_phases(&result.direct_phases, sd);		shader_copy_volume_phases(&result.direct_phases, sd);

/* Multiple importance sampling. */		/* Multiple importance sampling. */
Show All 20 Lines	if (1.0f - vstate.rscatter >= sample_transmittance) {
const float sample_sigma_t = volume_channel_get(coeff.sigma_t, channel);		const float sample_sigma_t = volume_channel_get(coeff.sigma_t, channel);
const float new_dt = -logf(1.0f - vstate.rscatter) / sample_sigma_t;		const float new_dt = -logf(1.0f - vstate.rscatter) / sample_sigma_t;
const float new_t = vstate.start_t + new_dt;		const float new_t = vstate.start_t + new_dt;

/* transmittance and pdf */		/* transmittance and pdf */
const float3 new_transmittance = volume_color_transmittance(coeff.sigma_t, new_dt);		const float3 new_transmittance = volume_color_transmittance(coeff.sigma_t, new_dt);
const float distance_pdf = dot(channel_pdf, coeff.sigma_t * new_transmittance);		const float distance_pdf = dot(channel_pdf, coeff.sigma_t * new_transmittance);

		if (vstate.distance_pdf * distance_pdf > VOLUME_SAMPLE_PDF_CUTOFF) {
/* throughput */		/* throughput */
result.indirect_scatter = true;		result.indirect_scatter = true;
result.indirect_t = new_t;		result.indirect_t = new_t;
result.indirect_throughput = coeff.sigma_s new_transmittance / distance_pdf;		result.indirect_throughput = coeff.sigma_s new_transmittance / distance_pdf;
shader_copy_volume_phases(&result.indirect_phases, sd);		shader_copy_volume_phases(&result.indirect_phases, sd);

if (vstate.direct_sample_method != VOLUME_SAMPLE_EQUIANGULAR) {		if (vstate.direct_sample_method != VOLUME_SAMPLE_EQUIANGULAR) {
/* If using distance sampling for direct light, just copy parameters		/* If using distance sampling for direct light, just copy parameters
* of indirect light since we scatter at the same point then. */		* of indirect light since we scatter at the same point then. */
result.direct_scatter = true;		result.direct_scatter = true;
result.direct_t = result.indirect_t;		result.direct_t = result.indirect_t;
result.direct_throughput = result.indirect_throughput;		result.direct_throughput = result.indirect_throughput;
shader_copy_volume_phases(&result.direct_phases, sd);		shader_copy_volume_phases(&result.direct_phases, sd);

/* Multiple importance sampling. */		/* Multiple importance sampling. */
if (vstate.use_mis) {		if (vstate.use_mis) {
const float equiangular_pdf = volume_equiangular_pdf(ray, equiangular_light_P, new_t);		const float equiangular_pdf = volume_equiangular_pdf(ray, equiangular_light_P, new_t);
const float mis_weight = power_heuristic(vstate.distance_pdf * distance_pdf,		const float mis_weight = power_heuristic(vstate.distance_pdf * distance_pdf,
equiangular_pdf);		equiangular_pdf);
result.direct_throughput = 2.0f mis_weight;		result.direct_throughput = 2.0f mis_weight;
}		}
}		}
}		}
		}
else {		else {
/* throughput */		/* throughput */
const float pdf = dot(channel_pdf, transmittance);		const float pdf = dot(channel_pdf, transmittance);
result.indirect_throughput *= transmittance / pdf;		result.indirect_throughput *= transmittance / pdf;
if (vstate.direct_sample_method != VOLUME_SAMPLE_EQUIANGULAR) {		if (vstate.direct_sample_method != VOLUME_SAMPLE_EQUIANGULAR) {
vstate.distance_pdf *= pdf;		vstate.distance_pdf *= pdf;
}		}

▲ Show 20 Lines • Show All 181 Lines • ▼ Show 20 Lines	ccl_device_forceinline bool integrate_volume_sample_light(
}		}

/* Sample position on a light. */		/* Sample position on a light. */
const uint32_t path_flag = INTEGRATOR_STATE(state, path, flag);		const uint32_t path_flag = INTEGRATOR_STATE(state, path, flag);
const uint bounce = INTEGRATOR_STATE(state, path, bounce);		const uint bounce = INTEGRATOR_STATE(state, path, bounce);
float light_u, light_v;		float light_u, light_v;
path_state_rng_2D(kg, rng_state, PRNG_LIGHT_U, &light_u, &light_v);		path_state_rng_2D(kg, rng_state, PRNG_LIGHT_U, &light_u, &light_v);

light_distribution_sample_from_volume_segment(		if (!light_distribution_sample_from_volume_segment(
kg, light_u, light_v, sd->time, sd->P, bounce, path_flag, ls);		kg, light_u, light_v, sd->time, sd->P, bounce, path_flag, ls)) {
		return false;
		}

if (ls->shader & SHADER_EXCLUDE_SCATTER) {		if (ls->shader & SHADER_EXCLUDE_SCATTER) {
return false;		return false;
}		}

return true;		return true;
}		}

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