Fix T54317: overlapping volume render bug after recent changes.

Increasing the samplig dimensions like this is not optimal, I'm looking
into some deeper changes to reuse the random number and change the RR
probabilities, but this should fix the bug for now.

1 files changed, 17 insertions, 0 deletions

diff --git a/intern/cycles/kernel/kernel_path_state.h b/intern/cycles/kernel/kernel_path_state.h
index ff7d1307a6c..90937dbf86e 100644
--- a/intern/cycles/kernel/kernel_path_state.h
+++ b/intern/cycles/kernel/kernel_path_state.h
@@ -166,6 +166,23 @@ ccl_device_inline void path_state_next(KernelGlobals *kg, ccl_addr_space PathSta
 #endif
 }
 
+ccl_device_inline bool path_state_volume_next(KernelGlobals *kg, ccl_addr_space PathState *state)
+{
+	/* For volume bounding meshes we pass through without counting transparent
+	 * bounces, only sanity check in case self intersection gets us stuck. */
+	state->volume_bounds_bounce++;
+	if (state->volume_bounds_bounce > VOLUME_BOUNDS_MAX) {
+		return false;
+	}
+
+	/* Random number generator next bounce. */
+	if(state->volume_bounds_bounce > 1) {
+		state->rng_offset += PRNG_BOUNCE_NUM;
+	}
+
+	return true;
+}
+
 ccl_device_inline uint path_state_ray_visibility(KernelGlobals *kg, ccl_addr_space PathState *state)
 {
 	uint flag = state->flag & PATH_RAY_ALL_VISIBILITY;