Cycles: remove disabled kernel_volume_get_final_homogeneous_extinction code.soc-2013-dingto

I'm not quite sure why this would be needed. It gives per color channel sigma,
which we should have so we can compute per channel attentuation without noise
instead of the single float now.

However I think this should be handled at a deeper level by making sigma a
float3 everywhere instead of doing some kind of correction for this afterwards.

1 files changed, 3 insertions, 173 deletions

diff --git a/intern/cycles/kernel/kernel_volume.h b/intern/cycles/kernel/kernel_volume.h
index 495642af0f2..50e44b6b589 100644
--- a/intern/cycles/kernel/kernel_volume.h
+++ b/intern/cycles/kernel/kernel_volume.h
@@ -65,110 +65,6 @@ ccl_device float get_sigma_sample(KernelGlobals *kg, ShaderData *sd, int path_fl
 	return sigma_from_value(v, 1.0f);
 }
 
-ccl_device  float3 kernel_volume_get_final_homogeneous_extinction_tsd(KernelGlobals *kg, ShaderData *sd, Ray ray, int path_flag, ShaderContext ctx)
-{
-	// return 3 transition extinction coefficients based on particle BRDF, base density and color
-	// make sense only for homogeneous volume for now
-	// the idea is to measure integral flux, not only individual free fly particles
-	// it help to get color gradients even with number of min/max bounces far from infinity
-	// NOTE: color must be constant as well, because we use it to modify extinction.
-
-	float3 res_sigma = make_float3(1.0f, 1.0f, 1.0f);
-	if((sd->flag & SD_HAS_VOLUME) != 0) { // check for empty volume shader
-		// base sigma
-		float base_sigma = get_sigma_sample(kg, sd, path_flag, ctx, ray.P);
-
-		// get transition probability
-		// or flux that pass forward even if catched by particle.
-		BsdfEval eval;
-		float3 omega_in = -sd->I;
-		float transition_pdf;
-		// FIXME: true only for g=0, need some weird integral for g != 0 cases. Sure not pdf directly,
-		// maybe lim(CPDF) when area -> omega_in ? Damn rocket science ...
-		shader_bsdf_eval(kg, sd, omega_in, &eval, &transition_pdf);
-#if 0
-		transition_pdf = single_peaked_henyey_greenstein(1.0f, 0.6);
-#endif
-
-		shader_eval_volume(kg, sd, 0.0f, path_flag, ctx);
-
-		/* todo: this assumes global density and is broken, color is per closure! */
-		int sampled = 0;
-		const ShaderClosure *sc = &sd->closure[sampled];
-		float3 color = sc->weight;
-
-#if 1
-//		res_sigma = make_float3(base_sigma, base_sigma, base_sigma) / ( make_float3(transition_pdf, transition_pdf, transition_pdf) * color);
-//		res_sigma = make_float3(base_sigma, base_sigma, base_sigma) * ( make_float3(transition_pdf, transition_pdf, transition_pdf) * color);
-//		float3 k = make_float3(1.0f, 1.0f, 1.0f) - (make_float3(transition_pdf, transition_pdf, transition_pdf) * color);
-//		res_sigma = make_float3(base_sigma, base_sigma, base_sigma) * k;
-//		float3 k = make_float3(1.0f, 1.0f, 1.0f) - (make_float3(transition_pdf, transition_pdf, transition_pdf) * color);
-//		float3 k = (make_float3(transition_pdf, transition_pdf, transition_pdf) * color);
-//		res_sigma = make_float3(base_sigma, base_sigma, base_sigma) - k;
-//		res_sigma.x = base_sigma * (1.0f + logf(1.0f - transition_pdf * color.x));
-//		res_sigma.y = base_sigma * (1.0f + logf(1.0f - transition_pdf * color.y));
-//		res_sigma.z = base_sigma * (1.0f + logf(1.0f - transition_pdf * color.z));
-		res_sigma.x = base_sigma * (1.0f + logf(1.0f + (1.0f / M_E - 1.0f) * transition_pdf * color.x));
-		res_sigma.y = base_sigma * (1.0f + logf(1.0f + (1.0f / M_E - 1.0f) * transition_pdf * color.y));
-		res_sigma.z = base_sigma * (1.0f + logf(1.0f + (1.0f / M_E - 1.0f) * transition_pdf * color.z));
-//		printf("pdf=%g\n", transition_pdf);
-#else
-		res_sigma = (make_float3(transition_pdf, transition_pdf, transition_pdf) * color);		
-		res_sigma = min(res_sigma, 1.0f);
-#endif
-	}
-
-	return res_sigma;
-}
-
-/* unused */
-ccl_device float kernel_volume_homogeneous_pdf( KernelGlobals *kg, ShaderData *sd, ShaderContext ctx, float distance)
-{
-	/* todo: do we need path_flag? */
-	float sigma = get_sigma_sample(kg, sd, 0, ctx, make_float3(0.0f, 0.0f, 0.0f));
-
-#ifdef __VOLUME_USE_GUARANTEE_HIT_PROB
-	return sigma * exp(-distance * sigma) * VOLUME_GUARANTEE_HIT_PROB;
-#else
-	return sigma * exp(-distance * sigma);
-#endif
-}
-
-ccl_device float3 kernel_volume_get_final_homogeneous_extinction(KernelGlobals *kg, ShaderContext ctx, int media_volume_shader)
-{
-	ShaderData tsd;
-	Ray ray;
-	ray.P = make_float3(0.0f, 0.0f, 0.0f);
-	ray.D = make_float3(0.0f, 0.0f, 1.0f);
-	ray.t = 0.0f;
-	shader_setup_from_volume(kg, &tsd, &ray, media_volume_shader);
-	int path_flag = PATH_RAY_SHADOW; // why ?
-
-	float3 res_sigma = make_float3(1.0f, 1.0f, 1.0f);
-	if((tsd.flag & SD_HAS_VOLUME) != 0) { // check for empty volume shader
-		// base sigma
-		float base_sigma = get_sigma_sample(kg, &tsd, path_flag, ctx, ray.P);
-
-		// get transition probability
-		BsdfEval eval;
-		float3 omega_in = -tsd.I;
-		float transition_pdf;
-		shader_bsdf_eval(kg, &tsd, omega_in, &eval, &transition_pdf);
-
-		// colors
-		shader_eval_volume(kg, &tsd, 0.0f, path_flag, SHADER_CONTEXT_MAIN);
-
-		/* todo: this assumes global density and is broken, color is per closure! */
-		int sampled = 0;
-		const ShaderClosure *sc = &tsd.closure[sampled];
-		float3 color = sc->weight;
-
-		res_sigma = make_float3(base_sigma, base_sigma, base_sigma) / (make_float3(transition_pdf, transition_pdf, transition_pdf) * color);
-	}
-
-	return res_sigma;
-}
-
 ccl_device int get_media_volume_shader(KernelGlobals *kg, float3 P, int bounce)
 {
 	/* check all objects that intersect random ray from given point, assume we have perfect geometry (all meshes closed, correct faces direct
@@ -436,7 +332,6 @@ ccl_device int kernel_volumetric_homogeneous_sampler(KernelGlobals *kg, float ra
 		 return 0;
 	}
 
-#if 1
 	if (omega_cache) {
 		if(*omega_cache == 0.0f) {
 			*omega_cache =  get_sigma_sample(kg, sd, path_flag, ctx, ray.P);
@@ -445,11 +340,6 @@ ccl_device int kernel_volumetric_homogeneous_sampler(KernelGlobals *kg, float ra
 	}
 	else
 		sigma = get_sigma_sample(kg, sd, path_flag, ctx, ray.P);
-#else
-	float3 sigma3 = kernel_volume_get_final_homogeneous_extinction_tsd(kg, sd, ray, path_flag, ctx);
-	sigma = min( sigma3.x, sigma3.y);
-	sigma = min( sigma, sigma3.z);
-#endif
 
 	if(sigma < SIGMA_MAGIC_EPS) {
 		/* Very transparent volume - Protect div by 0, *new_t = end; */
@@ -635,46 +525,12 @@ ccl_device float3 kernel_volume_get_shadow_attenuation(KernelGlobals *kg, RNG *r
 				attenuation = make_float3(1.0f, 1.0f, 1.0f);
 			else {
 				*volume_pdf =  sigma * exp(-light_ray->t * sigma);
-#if 0
-				float a = exp(-light_ray->t * sigma);
-				attenuation = make_float3(a, a, a);
-#else
-				// maybe it incorrect, but in homogeneous and constant color media we can analytically
-				// calculate transition color as well, based on knowledge of phase function probability
-				// in front direction, and integral of contributions of all possible combinations
-				// of direct light along straight line.
-				// (actually it only my guess, need to search correct integral, i assume it exp(-distance*sigma),
-				// remember we need complete unbiased multiscattering solution, not fake with 3 different color densities)
-				// In other words, try to calculate integral assuming Max Bounce = infinity along line.
-				// warning, require Color = constant as well as Homogeneous
-				// TODO: ensure that shader have color input unplugged.
-//				float3 color = make_float3(0.2f, 0.8f, 0.8f);
-//				float3 color = make_float3(0.5f, 0.99f, 0.99f);
-//				float3 tr_color = make_float3(1.0f, 1.0f, 1.0f) - color;
-//				float3 tr_color = color;
-#if 0
-				attenuation.x = exp(-light_ray->t * sigma / (transition_pdf * tr_color.x) );
-				attenuation.y = exp(-light_ray->t * sigma / (transition_pdf * tr_color.y) );
-				attenuation.z = exp(-light_ray->t * sigma / (transition_pdf * tr_color.z) );
-#else
-//				float3 sigma3 = kernel_volume_get_final_homogeneous_extinction_tsd(kg, &tsd, *light_ray, PATH_RAY_SHADOW, SHADER_CONTEXT_SHADOW);
-#if 1
-//				attenuation.x = exp(-light_ray->t * sigma3.x);
-//				attenuation.y = exp(-light_ray->t * sigma3.y);
-//				attenuation.z = exp(-light_ray->t * sigma3.z);
+
+				/* todo: sigma should become a float3 with per color channel
+				 * density returned by get_sigma_sample */
 				attenuation.x = exp(-light_ray->t * sigma);
 				attenuation.y = exp(-light_ray->t * sigma);
 				attenuation.z = exp(-light_ray->t * sigma);
-#else
-//				attenuation.x = exp(-light_ray->t * sigma3.x) + exp(-light_ray->t * sigma);
-//				attenuation.y = exp(-light_ray->t * sigma3.y) + exp(-light_ray->t * sigma);
-//				attenuation.z = exp(-light_ray->t * sigma3.z) + exp(-light_ray->t * sigma);
-				attenuation.x = exp(-light_ray->t * sigma) + (1.0f - exp(-light_ray->t * sigma)) * sigma3.x;
-				attenuation.y = exp(-light_ray->t * sigma) + (1.0f - exp(-light_ray->t * sigma)) * sigma3.y;
-				attenuation.z = exp(-light_ray->t * sigma) + (1.0f - exp(-light_ray->t * sigma)) * sigma3.z;
-#endif
-#endif
-#endif
 			}
 
 		}
@@ -957,32 +813,6 @@ ccl_device int kernel_path_trace_volume(KernelGlobals *kg, RNG *rng, int rng_off
 	*volume_eval = make_float3( eval, eval, eval);
 	//*volume_eval = make_float3( *volume_pdf, *volume_pdf, *volume_pdf);  // perfect importance sampling for homogeneous
 
-	// even if we missed any volume particle and hit face after it, we still modify color
-	// by transition attenuation, to respect "leaked" light because of scattering in strong forward direction
-	if (vsd.flag & SD_HOMOGENEOUS_VOLUME)
-	{
-		//int path_flag = 0;
-	
-		//float sigma = get_sigma_sample(kg, &vsd, randp, PATH_RAY_SHADOW, SHADER_CONTEXT_VOLUME, ray->P/* + ray.D * start*/);
-		//if (sigma < 0.0f) sigma = 0.0f;
-		//float3 sigma3 = kernel_volume_get_final_homogeneous_extinction_tsd(kg, &vsd, randp, *ray, path_flag, SHADER_CONTEXT_VOLUME);
-		//float3 attenuation;
-//		attenuation.x = exp(-isect_t* sigma3.x);
-//		attenuation.y = exp(-isect_t* sigma3.y);
-//		attenuation.z = exp(-isect_t* sigma3.z);
-//		bsdf_eval_mul(&bsdf_eval, attenuation);
-//		*throughput *= attenuation;
-//		*throughput += attenuation;
-//		attenuation.x = (1.0f - exp(-isect_t* sigma)) * sigma3.x;
-//		attenuation.y = (1.0f - exp(-isect_t* sigma)) * sigma3.y;
-//		attenuation.z = (1.0f - exp(-isect_t* sigma)) * sigma3.z;
-		//attenuation.x = exp(-isect_t* sigma3.x) - exp(-isect_t* sigma);
-		//attenuation.y = exp(-isect_t* sigma3.y) - exp(-isect_t* sigma);
-		//attenuation.z = exp(-isect_t* sigma3.z) - exp(-isect_t* sigma);
-//		*throughput *= (make_float3(1.0f, 1.0f, 1.0f) + attenuation);
-		//*volume_eval = make_float3( *volume_pdf, *volume_pdf, *volume_pdf);  // perfect importance sampling for homogeneous
-	}
-
 	return VOLUME_PATH_PARTICLE_MISS;
 }