/*
 * Adapted from code Copyright 2009-2010 NVIDIA Corporation
 * Modifications Copyright 2011, Blender Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* BVH
 *
 * Bounding volume hierarchy for ray tracing. We compile different variations
 * of the same BVH traversal function for faster rendering when some types of
 * primitives are not needed, using #includes to work around the lack of
 * C++ templates in OpenCL.
 *
 * Originally based on "Understanding the Efficiency of Ray Traversal on GPUs",
 * the code has been extended and modified to support more primitives and work
 * with CPU/CUDA/OpenCL. */

CCL_NAMESPACE_BEGIN

/* Don't inline intersect functions on GPU, this is faster */
#ifdef __KERNEL_GPU__
#define ccl_device_intersect ccl_device_noinline
#else
#define ccl_device_intersect ccl_device_inline
#endif

/* BVH intersection function variations */

#define BVH_INSTANCING			1
#define BVH_MOTION				2
#define BVH_HAIR				4
#define BVH_HAIR_MINIMUM_WIDTH	8

#define BVH_NAME_JOIN(x,y) x ## _ ## y
#define BVH_NAME_EVAL(x,y) BVH_NAME_JOIN(x,y)
#define BVH_FUNCTION_FULL_NAME(prefix) BVH_NAME_EVAL(prefix, BVH_FUNCTION_NAME)

#define BVH_FEATURE(f) (((BVH_FUNCTION_FEATURES) & (f)) != 0)

/* Common QBVH functions. */
#ifdef __QBVH__
#include "geom_qbvh.h"
#endif

/* Regular BVH traversal */

#define BVH_FUNCTION_NAME bvh_intersect
#define BVH_FUNCTION_FEATURES 0
#include "geom_bvh_traversal.h"

#if defined(__INSTANCING__)
#define BVH_FUNCTION_NAME bvh_intersect_instancing
#define BVH_FUNCTION_FEATURES BVH_INSTANCING
#include "geom_bvh_traversal.h"
#endif

#if defined(__HAIR__)
#define BVH_FUNCTION_NAME bvh_intersect_hair
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_HAIR|BVH_HAIR_MINIMUM_WIDTH
#include "geom_bvh_traversal.h"
#endif

#if defined(__OBJECT_MOTION__)
#define BVH_FUNCTION_NAME bvh_intersect_motion
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_MOTION
#include "geom_bvh_traversal.h"
#endif

#if defined(__HAIR__) && defined(__OBJECT_MOTION__)
#define BVH_FUNCTION_NAME bvh_intersect_hair_motion
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_HAIR|BVH_HAIR_MINIMUM_WIDTH|BVH_MOTION
#include "geom_bvh_traversal.h"
#endif

/* Subsurface scattering BVH traversal */

#if defined(__SUBSURFACE__)
#define BVH_FUNCTION_NAME bvh_intersect_subsurface
#define BVH_FUNCTION_FEATURES 0
#include "geom_bvh_subsurface.h"
#endif

#if defined(__SUBSURFACE__) && defined(__INSTANCING__)
#define BVH_FUNCTION_NAME bvh_intersect_subsurface_instancing
#define BVH_FUNCTION_FEATURES BVH_INSTANCING
#include "geom_bvh_subsurface.h"
#endif

#if defined(__SUBSURFACE__) && defined(__HAIR__)
#define BVH_FUNCTION_NAME bvh_intersect_subsurface_hair
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_HAIR
#include "geom_bvh_subsurface.h"
#endif

#if defined(__SUBSURFACE__) && defined(__OBJECT_MOTION__)
#define BVH_FUNCTION_NAME bvh_intersect_subsurface_motion
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_MOTION
#include "geom_bvh_subsurface.h"
#endif

#if defined(__SUBSURFACE__) && defined(__HAIR__) && defined(__OBJECT_MOTION__)
#define BVH_FUNCTION_NAME bvh_intersect_subsurface_hair_motion
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_HAIR|BVH_MOTION
#include "geom_bvh_subsurface.h"
#endif

/* Volume BVH traversal */

#if defined(__VOLUME__)
#define BVH_FUNCTION_NAME bvh_intersect_volume
#define BVH_FUNCTION_FEATURES 0
#include "geom_bvh_volume.h"
#endif

#if defined(__VOLUME__) && defined(__INSTANCING__)
#define BVH_FUNCTION_NAME bvh_intersect_volume_instancing
#define BVH_FUNCTION_FEATURES BVH_INSTANCING
#include "geom_bvh_volume.h"
#endif

#if defined(__VOLUME__) && defined(__HAIR__)
#define BVH_FUNCTION_NAME bvh_intersect_volume_hair
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_HAIR|BVH_HAIR_MINIMUM_WIDTH
#include "geom_bvh_volume.h"
#endif

#if defined(__VOLUME__) && defined(__OBJECT_MOTION__)
#define BVH_FUNCTION_NAME bvh_intersect_volume_motion
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_MOTION
#include "geom_bvh_volume.h"
#endif

#if defined(__VOLUME__) && defined(__HAIR__) && defined(__OBJECT_MOTION__)
#define BVH_FUNCTION_NAME bvh_intersect_volume_hair_motion
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_HAIR|BVH_HAIR_MINIMUM_WIDTH|BVH_MOTION
#include "geom_bvh_volume.h"
#endif

/* Record all intersections - Shadow BVH traversal */

#if defined(__SHADOW_RECORD_ALL__)
#define BVH_FUNCTION_NAME bvh_intersect_shadow_all
#define BVH_FUNCTION_FEATURES 0
#include "geom_bvh_shadow.h"
#endif

#if defined(__SHADOW_RECORD_ALL__) && defined(__INSTANCING__)
#define BVH_FUNCTION_NAME bvh_intersect_shadow_all_instancing
#define BVH_FUNCTION_FEATURES BVH_INSTANCING
#include "geom_bvh_shadow.h"
#endif

#if defined(__SHADOW_RECORD_ALL__) && defined(__HAIR__)
#define BVH_FUNCTION_NAME bvh_intersect_shadow_all_hair
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_HAIR
#include "geom_bvh_shadow.h"
#endif

#if defined(__SHADOW_RECORD_ALL__) && defined(__OBJECT_MOTION__)
#define BVH_FUNCTION_NAME bvh_intersect_shadow_all_motion
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_MOTION
#include "geom_bvh_shadow.h"
#endif

#if defined(__SHADOW_RECORD_ALL__) && defined(__HAIR__) && defined(__OBJECT_MOTION__)
#define BVH_FUNCTION_NAME bvh_intersect_shadow_all_hair_motion
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_HAIR|BVH_MOTION
#include "geom_bvh_shadow.h"
#endif

/* Record all intersections - Volume BVH traversal  */

#if defined(__VOLUME_RECORD_ALL__)
#define BVH_FUNCTION_NAME bvh_intersect_volume_all
#define BVH_FUNCTION_FEATURES 0
#include "geom_bvh_volume_all.h"
#endif

#if defined(__VOLUME_RECORD_ALL__) && defined(__INSTANCING__)
#define BVH_FUNCTION_NAME bvh_intersect_volume_all_instancing
#define BVH_FUNCTION_FEATURES BVH_INSTANCING
#include "geom_bvh_volume_all.h"
#endif

#if defined(__VOLUME_RECORD_ALL__) && defined(__HAIR__)
#define BVH_FUNCTION_NAME bvh_intersect_volume_all_hair
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_HAIR|BVH_HAIR_MINIMUM_WIDTH
#include "geom_bvh_volume_all.h"
#endif

#if defined(__VOLUME_RECORD_ALL__) && defined(__OBJECT_MOTION__)
#define BVH_FUNCTION_NAME bvh_intersect_volume_all_motion
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_MOTION
#include "geom_bvh_volume_all.h"
#endif

#if defined(__VOLUME_RECORD_ALL__) && defined(__HAIR__) && defined(__OBJECT_MOTION__)
#define BVH_FUNCTION_NAME bvh_intersect_volume_all_hair_motion
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_HAIR|BVH_HAIR_MINIMUM_WIDTH|BVH_MOTION
#include "geom_bvh_volume_all.h"
#endif

#undef BVH_FEATURE
#undef BVH_NAME_JOIN
#undef BVH_NAME_EVAL
#undef BVH_FUNCTION_FULL_NAME

ccl_device_intersect bool scene_intersect(KernelGlobals *kg,
                                          const Ray *ray,
                                          const uint visibility,
                                          Intersection *isect,
                                          uint *lcg_state,
                                          float difl,
                                          float extmax)
{
#ifdef __OBJECT_MOTION__
	if(kernel_data.bvh.have_motion) {
#ifdef __HAIR__
		if(kernel_data.bvh.have_curves)
			return bvh_intersect_hair_motion(kg, ray, isect, visibility, lcg_state, difl, extmax);
#endif /* __HAIR__ */

		return bvh_intersect_motion(kg, ray, isect, visibility);
	}
#endif /* __OBJECT_MOTION__ */

#ifdef __HAIR__ 
	if(kernel_data.bvh.have_curves)
		return bvh_intersect_hair(kg, ray, isect, visibility, lcg_state, difl, extmax);
#endif /* __HAIR__ */

#ifdef __KERNEL_CPU__

#ifdef __INSTANCING__
	if(kernel_data.bvh.have_instancing)
		return bvh_intersect_instancing(kg, ray, isect, visibility);
#endif /* __INSTANCING__ */

	return bvh_intersect(kg, ray, isect, visibility);
#else /* __KERNEL_CPU__ */

#ifdef __INSTANCING__
	return bvh_intersect_instancing(kg, ray, isect, visibility);
#else
	return bvh_intersect(kg, ray, isect, visibility);
#endif /* __INSTANCING__ */

#endif /* __KERNEL_CPU__ */
}

#ifdef __SUBSURFACE__
ccl_device_intersect void scene_intersect_subsurface(KernelGlobals *kg,
                                                     const Ray *ray,
                                                     SubsurfaceIntersection *ss_isect,
                                                     int subsurface_object,
                                                     uint *lcg_state,
                                                     int max_hits)
{
#ifdef __OBJECT_MOTION__
	if(kernel_data.bvh.have_motion) {
#ifdef __HAIR__
		if(kernel_data.bvh.have_curves) {
			return bvh_intersect_subsurface_hair_motion(kg,
			                                            ray,
			                                            ss_isect,
			                                            subsurface_object,
			                                            lcg_state,
			                                            max_hits);
		}
#endif /* __HAIR__ */

		return bvh_intersect_subsurface_motion(kg,
		                                       ray,
		                                       ss_isect,
		                                       subsurface_object,
		                                       lcg_state,
		                                       max_hits);
	}
#endif /* __OBJECT_MOTION__ */

#ifdef __HAIR__
	if(kernel_data.bvh.have_curves) {
		return bvh_intersect_subsurface_hair(kg,
		                                     ray,
		                                     ss_isect,
		                                     subsurface_object,
		                                     lcg_state,
		                                     max_hits);
	}
#endif /* __HAIR__ */

#ifdef __KERNEL_CPU__

#ifdef __INSTANCING__
	if(kernel_data.bvh.have_instancing) {
		return bvh_intersect_subsurface_instancing(kg,
		                                           ray,
		                                           ss_isect,
		                                           subsurface_object,
		                                           lcg_state,
		                                           max_hits);
	}
#endif /* __INSTANCING__ */

	return bvh_intersect_subsurface(kg,
	                                ray,
	                                ss_isect,
	                                subsurface_object,
	                                lcg_state,
	                                max_hits);
#else /* __KERNEL_CPU__ */

#ifdef __INSTANCING__
	return bvh_intersect_subsurface_instancing(kg,
	                                           ray,
	                                           ss_isect,
	                                           subsurface_object,
	                                           lcg_state,
	                                           max_hits);
#else
	return bvh_intersect_subsurface(kg,
	                                ray,
	                                ss_isect,
	                                subsurface_object,
	                                lcg_state,
	                                max_hits);
#endif /* __INSTANCING__ */

#endif /* __KERNEL_CPU__ */
}
#endif

#ifdef __SHADOW_RECORD_ALL__
ccl_device_intersect bool scene_intersect_shadow_all(KernelGlobals *kg, const Ray *ray, Intersection *isect, uint max_hits, uint *num_hits)
{
#ifdef __OBJECT_MOTION__
	if(kernel_data.bvh.have_motion) {
#ifdef __HAIR__
		if(kernel_data.bvh.have_curves)
			return bvh_intersect_shadow_all_hair_motion(kg, ray, isect, max_hits, num_hits);
#endif /* __HAIR__ */

		return bvh_intersect_shadow_all_motion(kg, ray, isect, max_hits, num_hits);
	}
#endif /* __OBJECT_MOTION__ */

#ifdef __HAIR__ 
	if(kernel_data.bvh.have_curves)
		return bvh_intersect_shadow_all_hair(kg, ray, isect, max_hits, num_hits);
#endif /* __HAIR__ */

#ifdef __INSTANCING__
	if(kernel_data.bvh.have_instancing)
		return bvh_intersect_shadow_all_instancing(kg, ray, isect, max_hits, num_hits);
#endif /* __INSTANCING__ */

	return bvh_intersect_shadow_all(kg, ray, isect, max_hits, num_hits);
}
#endif

#ifdef __VOLUME__
ccl_device_intersect bool scene_intersect_volume(KernelGlobals *kg,
                                                 const Ray *ray,
                                                 Intersection *isect,
                                                 const uint visibility)
{
#ifdef __OBJECT_MOTION__
	if(kernel_data.bvh.have_motion) {
#ifdef __HAIR__
		if(kernel_data.bvh.have_curves)
			return bvh_intersect_volume_hair_motion(kg, ray, isect, visibility);
#endif /* __HAIR__ */

		return bvh_intersect_volume_motion(kg, ray, isect, visibility);
	}
#endif /* __OBJECT_MOTION__ */

#ifdef __HAIR__
	if(kernel_data.bvh.have_curves)
		return bvh_intersect_volume_hair(kg, ray, isect, visibility);
#endif /* __HAIR__ */

#ifdef __KERNEL_CPU__

#ifdef __INSTANCING__
	if(kernel_data.bvh.have_instancing)
		return bvh_intersect_volume_instancing(kg, ray, isect, visibility);
#endif /* __INSTANCING__ */

	return bvh_intersect_volume(kg, ray, isect, visibility);
#else /* __KERNEL_CPU__ */

#ifdef __INSTANCING__
	return bvh_intersect_volume_instancing(kg, ray, isect, visibility);
#else
	return bvh_intersect_volume(kg, ray, isect, visibility);
#endif /* __INSTANCING__ */

#endif /* __KERNEL_CPU__ */
}
#endif

#ifdef __VOLUME_RECORD_ALL__
ccl_device_intersect uint scene_intersect_volume_all(KernelGlobals *kg,
                                                     const Ray *ray,
                                                     Intersection *isect,
                                                     const uint max_hits,
                                                     const uint visibility)
{
#ifdef __OBJECT_MOTION__
	if(kernel_data.bvh.have_motion) {
#ifdef __HAIR__
		if(kernel_data.bvh.have_curves)
			return bvh_intersect_volume_all_hair_motion(kg, ray, isect, max_hits, visibility);
#endif /* __HAIR__ */

		return bvh_intersect_volume_all_motion(kg, ray, isect, max_hits, visibility);
	}
#endif /* __OBJECT_MOTION__ */

#ifdef __HAIR__
	if(kernel_data.bvh.have_curves)
		return bvh_intersect_volume_all_hair(kg, ray, isect, max_hits, visibility);
#endif /* __HAIR__ */

#ifdef __INSTANCING__
	if(kernel_data.bvh.have_instancing)
		return bvh_intersect_volume_all_instancing(kg, ray, isect, max_hits, visibility);
#endif /* __INSTANCING__ */

	return bvh_intersect_volume_all(kg, ray, isect, max_hits, visibility);
}
#endif


/* Ray offset to avoid self intersection.
 *
 * This function should be used to compute a modified ray start position for
 * rays leaving from a surface. */

ccl_device_inline float3 ray_offset(float3 P, float3 Ng)
{
#ifdef __INTERSECTION_REFINE__
	const float epsilon_f = 1e-5f;
	/* ideally this should match epsilon_f, but instancing and motion blur
	 * precision makes it problematic */
	const float epsilon_test = 1.0f;
	const int epsilon_i = 32;

	float3 res;

	/* x component */
	if(fabsf(P.x) < epsilon_test) {
		res.x = P.x + Ng.x*epsilon_f;
	}
	else {
		uint ix = __float_as_uint(P.x);
		ix += ((ix ^ __float_as_uint(Ng.x)) >> 31)? -epsilon_i: epsilon_i;
		res.x = __uint_as_float(ix);
	}

	/* y component */
	if(fabsf(P.y) < epsilon_test) {
		res.y = P.y + Ng.y*epsilon_f;
	}
	else {
		uint iy = __float_as_uint(P.y);
		iy += ((iy ^ __float_as_uint(Ng.y)) >> 31)? -epsilon_i: epsilon_i;
		res.y = __uint_as_float(iy);
	}

	/* z component */
	if(fabsf(P.z) < epsilon_test) {
		res.z = P.z + Ng.z*epsilon_f;
	}
	else {
		uint iz = __float_as_uint(P.z);
		iz += ((iz ^ __float_as_uint(Ng.z)) >> 31)? -epsilon_i: epsilon_i;
		res.z = __uint_as_float(iz);
	}

	return res;
#else
	const float epsilon_f = 1e-4f;
	return P + epsilon_f*Ng;
#endif
}

#if defined(__SHADOW_RECORD_ALL__) || defined (__VOLUME_RECORD_ALL__)
/* ToDo: Move to another file? */
ccl_device int intersections_compare(const void *a, const void *b)
{
	const Intersection *isect_a = (const Intersection*)a;
	const Intersection *isect_b = (const Intersection*)b;

	if(isect_a->t < isect_b->t)
		return -1;
	else if(isect_a->t > isect_b->t)
		return 1;
	else
		return 0;
}
#endif

CCL_NAMESPACE_END

