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Fix T43562: Cycles gets stuck with camera in volume in certain setup 

The issue was caused by the way how we shoot the ray to see which rays we're
inside which might start bouncing back-n-forth between two close to parallel
intersecting faces.

Real solution would be to record all the intersections when shooting the ray,
but it's kinda tricky on GPU because of needed sorting and uncertainty of
how huge intersection array should be.

For now we'll just limit number of steps in the check so in worst case we'll
have some samples not being correct which will be compensated with further
sampling. Shouldn't be an issue since probability of such a lock is quite
small actually.
This commit is contained in:
Sergey Sharybin 2015-02-05 16:06:22 +05:00
parent 0527fc5fb8
commit 25f33e058a
Notes: blender-bot 2023-02-14 09:31:56 +01:00 
Referenced by issue #43562, Cycles gets stuck rendering final tile at 100% CPU
2 changed files with 8 additions and 3 deletions
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6
intern/cycles/kernel/kernel_path.h
View File

@ -373,8 +373,9 @@ ccl_device void kernel_path_subsurface_update_volume_stack(KernelGlobals *kg,
Ray volume_ray = *ray;
Intersection isect;
while(scene_intersect_volume(kg, &volume_ray, &isect))
int step = 0;
while(step < VOLUME_STACK_SIZE &&
scene_intersect_volume(kg, &volume_ray, &isect))
{
ShaderData sd;
shader_setup_from_ray(kg, &sd, &isect, &volume_ray, 0, 0);
@ -383,6 +384,7 @@ ccl_device void kernel_path_subsurface_update_volume_stack(KernelGlobals *kg,
/* Move ray forward. */
volume_ray.P = ray_offset(sd.P, -sd.Ng);
volume_ray.t -= sd.ray_length;
++step;
}
}
#endif

5
intern/cycles/kernel/kernel_volume.h
View File

@ -980,9 +980,11 @@ ccl_device void kernel_volume_stack_init(KernelGlobals *kg,
int stack_index = 0, enclosed_index = 0;
int enclosed_volumes[VOLUME_STACK_SIZE];
int step = 0;
while(stack_index < VOLUME_STACK_SIZE - 1 &&
enclosed_index < VOLUME_STACK_SIZE - 1)
enclosed_index < VOLUME_STACK_SIZE - 1 &&
step < 2 * VOLUME_STACK_SIZE)
{
Intersection isect;
if(!scene_intersect_volume(kg, &volume_ray, &isect)) {
@ -1017,6 +1019,7 @@ ccl_device void kernel_volume_stack_init(KernelGlobals *kg,
/* Move ray forward. */
volume_ray.P = ray_offset(sd.P, -sd.Ng);
++step;
}
/* stack_index of 0 means quick checks outside of the kernel gave false
* positive, nothing to worry about, just we've wasted quite a few of