Cycles: Refactor how we pass bounce info to light path node.

This commit changes the way how we pass bounce information to the Light
Path node. Instead of manualy copying the bounces into ShaderData, we now
directly pass PathState. This reduces the arguments that we need to pass
around and also makes it easier to extend the feature.

This commit also exposes the Transmission Bounce Depth to the Light Path
node. It works similar to the Transparent Depth Output: Replace a
Transmission lightpath after X bounces with another shader, e.g a Diffuse
one. This can be used to avoid black surfaces, due to low amount of max
bounces.

Reviewed by Sergey and Brecht, thanks for some hlp with this.

I tested compilation and usage on CPU (SVM and OSL), CUDA, OpenCL Split
and Mega kernel. Hopefully this covers all devices. :)

1 files changed, 23 insertions, 23 deletions

diff --git a/intern/cycles/kernel/kernel_bake.h b/intern/cycles/kernel/kernel_bake.h
index b54afbd21b8..2a2220ceb99 100644
--- a/intern/cycles/kernel/kernel_bake.h
+++ b/intern/cycles/kernel/kernel_bake.h
@@ -46,7 +46,7 @@ ccl_device void compute_light_pass(KernelGlobals *kg, ShaderData *sd, PathRadian
 
 	/* evaluate surface shader */
 	float rbsdf = path_state_rng_1D(kg, &rng, &state, PRNG_BSDF);
-	shader_eval_surface(kg, sd, rbsdf, state.flag, SHADER_CONTEXT_MAIN);
+	shader_eval_surface(kg, sd, &state, rbsdf, state.flag, SHADER_CONTEXT_MAIN);
 
 	/* TODO, disable the closures we won't need */
 
@@ -212,6 +212,7 @@ ccl_device void kernel_bake_evaluate(KernelGlobals *kg, ccl_global uint4 *input,
                                      ShaderEvalType type, int i, int offset, int sample)
 {
 	ShaderData sd;
+	PathState state = {0};
 	uint4 in = input[i * 2];
 	uint4 diff = input[i * 2 + 1];
 
@@ -262,13 +263,11 @@ ccl_device void kernel_bake_evaluate(KernelGlobals *kg, ccl_global uint4 *input,
 	float3 I = Ng;
 	float t = 0.0f;
 	float time = TIME_INVALID;
-	int bounce = 0;
-	int transparent_bounce = 0;
 
 	/* light passes */
 	PathRadiance L;
 
-	shader_setup_from_sample(kg, &sd, P, Ng, I, shader, object, prim, u, v, t, time, bounce, transparent_bounce);
+	shader_setup_from_sample(kg, &sd, P, Ng, I, shader, object, prim, u, v, t, time);
 	sd.I = sd.N;
 
 	/* update differentials */
@@ -294,7 +293,7 @@ ccl_device void kernel_bake_evaluate(KernelGlobals *kg, ccl_global uint4 *input,
 		case SHADER_EVAL_NORMAL:
 		{
 			if((sd.flag & SD_HAS_BUMP)) {
-				shader_eval_surface(kg, &sd, 0.f, 0, SHADER_CONTEXT_MAIN);
+				shader_eval_surface(kg, &sd, &state, 0.f, 0, SHADER_CONTEXT_MAIN);
 			}
 
 			/* compression: normal = (2 * color) - 1 */
@@ -308,33 +307,33 @@ ccl_device void kernel_bake_evaluate(KernelGlobals *kg, ccl_global uint4 *input,
 		}
 		case SHADER_EVAL_DIFFUSE_COLOR:
 		{
-			shader_eval_surface(kg, &sd, 0.f, 0, SHADER_CONTEXT_MAIN);
+			shader_eval_surface(kg, &sd, &state, 0.f, 0, SHADER_CONTEXT_MAIN);
 			out = shader_bsdf_diffuse(kg, &sd);
 			break;
 		}
 		case SHADER_EVAL_GLOSSY_COLOR:
 		{
-			shader_eval_surface(kg, &sd, 0.f, 0, SHADER_CONTEXT_MAIN);
+			shader_eval_surface(kg, &sd, &state, 0.f, 0, SHADER_CONTEXT_MAIN);
 			out = shader_bsdf_glossy(kg, &sd);
 			break;
 		}
 		case SHADER_EVAL_TRANSMISSION_COLOR:
 		{
-			shader_eval_surface(kg, &sd, 0.f, 0, SHADER_CONTEXT_MAIN);
+			shader_eval_surface(kg, &sd, &state, 0.f, 0, SHADER_CONTEXT_MAIN);
 			out = shader_bsdf_transmission(kg, &sd);
 			break;
 		}
 		case SHADER_EVAL_SUBSURFACE_COLOR:
 		{
 #ifdef __SUBSURFACE__
-			shader_eval_surface(kg, &sd, 0.f, 0, SHADER_CONTEXT_MAIN);
+			shader_eval_surface(kg, &sd, &state, 0.f, 0, SHADER_CONTEXT_MAIN);
 			out = shader_bsdf_subsurface(kg, &sd);
 #endif
 			break;
 		}
 		case SHADER_EVAL_EMISSION:
 		{
-			shader_eval_surface(kg, &sd, 0.f, 0, SHADER_CONTEXT_EMISSION);
+			shader_eval_surface(kg, &sd, &state, 0.f, 0, SHADER_CONTEXT_EMISSION);
 			out = shader_emissive_eval(kg, &sd);
 			break;
 		}
@@ -358,52 +357,52 @@ ccl_device void kernel_bake_evaluate(KernelGlobals *kg, ccl_global uint4 *input,
 		}
 		case SHADER_EVAL_DIFFUSE_DIRECT:
 		{
-			shader_eval_surface(kg, &sd, 0.f, 0, SHADER_CONTEXT_MAIN);
+			shader_eval_surface(kg, &sd, &state, 0.f, 0, SHADER_CONTEXT_MAIN);
 			out = safe_divide_color(L.direct_diffuse, shader_bsdf_diffuse(kg, &sd));
 			break;
 		}
 		case SHADER_EVAL_GLOSSY_DIRECT:
 		{
-			shader_eval_surface(kg, &sd, 0.f, 0, SHADER_CONTEXT_MAIN);
+			shader_eval_surface(kg, &sd, &state, 0.f, 0, SHADER_CONTEXT_MAIN);
 			out = safe_divide_color(L.direct_glossy, shader_bsdf_glossy(kg, &sd));
 			break;
 		}
 		case SHADER_EVAL_TRANSMISSION_DIRECT:
 		{
-			shader_eval_surface(kg, &sd, 0.f, 0, SHADER_CONTEXT_MAIN);
+			shader_eval_surface(kg, &sd, &state, 0.f, 0, SHADER_CONTEXT_MAIN);
 			out = safe_divide_color(L.direct_transmission, shader_bsdf_transmission(kg, &sd));
 			break;
 		}
 		case SHADER_EVAL_SUBSURFACE_DIRECT:
 		{
 #ifdef __SUBSURFACE__
-			shader_eval_surface(kg, &sd, 0.f, 0, SHADER_CONTEXT_MAIN);
+			shader_eval_surface(kg, &sd, &state, 0.f, 0, SHADER_CONTEXT_MAIN);
 			out = safe_divide_color(L.direct_subsurface, shader_bsdf_subsurface(kg, &sd));
 #endif
 			break;
 		}
 		case SHADER_EVAL_DIFFUSE_INDIRECT:
 		{
-			shader_eval_surface(kg, &sd, 0.f, 0, SHADER_CONTEXT_MAIN);
+			shader_eval_surface(kg, &sd, &state, 0.f, 0, SHADER_CONTEXT_MAIN);
 			out = safe_divide_color(L.indirect_diffuse, shader_bsdf_diffuse(kg, &sd));
 			break;
 		}
 		case SHADER_EVAL_GLOSSY_INDIRECT:
 		{
-			shader_eval_surface(kg, &sd, 0.f, 0, SHADER_CONTEXT_MAIN);
+			shader_eval_surface(kg, &sd, &state, 0.f, 0, SHADER_CONTEXT_MAIN);
 			out = safe_divide_color(L.indirect_glossy, shader_bsdf_glossy(kg, &sd));
 			break;
 		}
 		case SHADER_EVAL_TRANSMISSION_INDIRECT:
 		{
-			shader_eval_surface(kg, &sd, 0.f, 0, SHADER_CONTEXT_MAIN);
+			shader_eval_surface(kg, &sd, &state, 0.f, 0, SHADER_CONTEXT_MAIN);
 			out = safe_divide_color(L.indirect_transmission, shader_bsdf_transmission(kg, &sd));
 			break;
 		}
 		case SHADER_EVAL_SUBSURFACE_INDIRECT:
 		{
 #ifdef __SUBSURFACE__
-			shader_eval_surface(kg, &sd, 0.f, 0, SHADER_CONTEXT_MAIN);
+			shader_eval_surface(kg, &sd, &state, 0.f, 0, SHADER_CONTEXT_MAIN);
 			out = safe_divide_color(L.indirect_subsurface, shader_bsdf_subsurface(kg, &sd));
 #endif
 			break;
@@ -429,11 +428,11 @@ ccl_device void kernel_bake_evaluate(KernelGlobals *kg, ccl_global uint4 *input,
 #endif
 
 			/* setup shader data */
-			shader_setup_from_background(kg, &sd, &ray, 0, 0);
+			shader_setup_from_background(kg, &sd, &ray);
 
 			/* evaluate */
 			int flag = 0; /* we can't know which type of BSDF this is for */
-			out = shader_eval_background(kg, &sd, flag, SHADER_CONTEXT_MAIN);
+			out = shader_eval_background(kg, &sd, &state, flag, SHADER_CONTEXT_MAIN);
 			break;
 		}
 		default:
@@ -462,6 +461,7 @@ ccl_device void kernel_shader_evaluate(KernelGlobals *kg,
                                        int sample)
 {
 	ShaderData sd;
+	PathState state = {0};
 	uint4 in = input[i];
 	float3 out;
 
@@ -476,7 +476,7 @@ ccl_device void kernel_shader_evaluate(KernelGlobals *kg,
 
 		/* evaluate */
 		float3 P = sd.P;
-		shader_eval_displacement(kg, &sd, SHADER_CONTEXT_MAIN);
+		shader_eval_displacement(kg, &sd, &state, SHADER_CONTEXT_MAIN);
 		out = sd.P - P;
 	}
 	else { // SHADER_EVAL_BACKGROUND
@@ -498,11 +498,11 @@ ccl_device void kernel_shader_evaluate(KernelGlobals *kg,
 #endif
 
 		/* setup shader data */
-		shader_setup_from_background(kg, &sd, &ray, 0, 0);
+		shader_setup_from_background(kg, &sd, &ray);
 
 		/* evaluate */
 		int flag = 0; /* we can't know which type of BSDF this is for */
-		out = shader_eval_background(kg, &sd, flag, SHADER_CONTEXT_MAIN);
+		out = shader_eval_background(kg, &sd, &state, flag, SHADER_CONTEXT_MAIN);
 	}
 	
 	/* write output */