Cycles: fix issues rendering second render layer passes, and avoid unnecessary

clear of buffer.

intern/cycles/blender/blender_session.cpp

@@ -203,6 +203,9 @@ void BlenderSession::render()
 		b_rlay = *b_iter;
 
 		/* add passes */
+		vector<Pass> passes;
+		Pass::add(PASS_COMBINED, passes);
+
 		if(session_params.device.type == DEVICE_CPU) { /* todo */
 			BL::RenderLayer::passes_iterator b_pass_iter;
 			
@@ -211,12 +214,13 @@ void BlenderSession::render()
 				PassType pass_type = get_pass_type(b_pass);
 
 				if(pass_type != PASS_NONE)
-					Pass::add(pass_type, buffer_params.passes);
+					Pass::add(pass_type, passes);
 			}
 		}
 
-		scene->film->passes = buffer_params.passes;
+		buffer_params.passes = passes;
-		scene->film->need_update = true;
+		scene->film->passes = passes;
+		scene->film->tag_update(scene);
 
 		/* update session */
 		session->reset(buffer_params, session_params.samples);

intern/cycles/kernel/kernel_passes.h

@@ -36,15 +36,6 @@ __device_inline void kernel_write_pass_float4(__global float *buffer, int sample
 	*buf = (sample == 0)? value: *buf + value;
 }
 
-__device_inline void kernel_clear_passes(__global float *buffer, int sample, int pass_stride)
-{
-#ifdef __PASSES__
-	if(sample == 0 && pass_stride != 4)
-		for(int i = 4; i < pass_stride; i++)
-			buffer[i] = 0.0f;
-#endif
-}
-
 __device void kernel_write_data_passes(KernelGlobals *kg, __global float *buffer, PathRadiance *L,
 	ShaderData *sd, int sample, int path_flag, float3 throughput)
 {

intern/cycles/kernel/kernel_path.h

@@ -377,8 +377,6 @@ __device void kernel_path_trace(KernelGlobals *kg,
 	rng_state += index;
 	buffer += index*pass_stride;
 
-	kernel_clear_passes(buffer, sample, pass_stride);
-
 	/* initialize random numbers */
 	RNG rng;
 

intern/cycles/render/buffers.cpp

@@ -157,12 +157,19 @@ bool RenderBuffers::get_pass(PassType type, float exposure, int sample, int comp
 			assert(pass.components == components);
 
 			/* scalar */
+			if(type == PASS_DEPTH) {
+				for(int i = 0; i < size; i++, in += pass_stride, pixels++) {
+					float f = *in;
+					pixels[0] = (f == 0.0f)? 1e10f: f*scale_exposure;
+				}
+			}
+			else {
 				for(int i = 0; i < size; i++, in += pass_stride, pixels++) {
 					float f = *in;
-
 					pixels[0] = f*scale_exposure;
 				}
 			}
+		}
 		else if(components == 3) {
 			assert(pass.components == 4);