Cycles-Bake: displacement support (fix T40068)

Code with contribution from Brecht Van Lommel.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D510

intern/cycles/blender/blender_session.cpp

@@ -487,7 +487,7 @@ static void populate_bake_data(BakeData *data, BL::BakePixel pixel_array, const
 
 	int i;
 	for(i=0; i < num_pixels; i++) {
-		data->set(i, bp.primitive_id(), bp.uv());
+		data->set(i, bp.primitive_id(), bp.uv(), bp.du_dx(), bp.du_dy(), bp.dv_dx(), bp.dv_dy());
 		bp = bp.next();
 	}
 }

intern/cycles/kernel/kernel_displace.h

@@ -102,7 +102,9 @@ ccl_device bool is_light_pass(ShaderEvalType type)
 ccl_device void kernel_bake_evaluate(KernelGlobals *kg, ccl_global uint4 *input, ccl_global float4 *output, ShaderEvalType type, int i)
 {
 	ShaderData sd;
-	uint4 in = input[i];
+	uint4 in = input[i * 2];
+	uint4 diff = input[i * 2 + 1];
+
 	float3 out;
 
 	int object = in.x;
@@ -114,6 +116,11 @@ ccl_device void kernel_bake_evaluate(KernelGlobals *kg, ccl_global uint4 *input,
 	float u = __uint_as_float(in.z);
 	float v = __uint_as_float(in.w);
 
+	float dudx = __uint_as_float(diff.x);
+	float dudy = __uint_as_float(diff.y);
+	float dvdx = __uint_as_float(diff.z);
+	float dvdy = __uint_as_float(diff.w);
+
 	int shader;
 	float3 P, Ng;
 
@@ -132,6 +139,14 @@ ccl_device void kernel_bake_evaluate(KernelGlobals *kg, ccl_global uint4 *input,
 	shader_setup_from_sample(kg, &sd, P, Ng, I, shader, object, prim, u, v, t, time, bounce, transparent_bounce);
 	sd.I = sd.N;
 
+	/* update differentials */
+	sd.dP.dx = sd.dPdu * dudx + sd.dPdv * dvdx;
+	sd.dP.dy = sd.dPdu * dudy + sd.dPdv * dvdy;
+	sd.du.dx = dudx;
+	sd.du.dy = dudy;
+	sd.dv.dx = dvdx;
+	sd.dv.dy = dvdy;
+
 	if(is_light_pass(type)) {
 		RNG rng = cmj_hash(i, 0);
 		compute_light_pass(kg, &sd, &L, rng, (type == SHADER_EVAL_COMBINED),

intern/cycles/render/bake.cpp

@@ -26,6 +26,10 @@ m_num_pixels(num_pixels)
 	m_primitive.resize(num_pixels);
 	m_u.resize(num_pixels);
 	m_v.resize(num_pixels);
+	m_dudx.resize(num_pixels);
+	m_dudy.resize(num_pixels);
+	m_dvdx.resize(num_pixels);
+	m_dvdy.resize(num_pixels);
 }
 
 BakeData::~BakeData()
@@ -33,13 +37,21 @@ BakeData::~BakeData()
 	m_primitive.clear();
 	m_u.clear();
 	m_v.clear();
+	m_dudx.clear();
+	m_dudy.clear();
+	m_dvdx.clear();
+	m_dvdy.clear();
 }
 
-void BakeData::set(int i, int prim, float uv[2])
+void BakeData::set(int i, int prim, float uv[2], float dudx, float dudy, float dvdx, float dvdy)
 {
 	m_primitive[i] = (prim == -1 ? -1 : m_tri_offset + prim);
 	m_u[i] = uv[0];
 	m_v[i] = uv[1];
+	m_dudx[i] = dudx;
+	m_dudy[i] = dudy;
+	m_dvdx[i] = dvdx;
+	m_dvdy[i] = dvdy;
 }
 
 int BakeData::object()
@@ -67,6 +79,16 @@ uint4 BakeData::data(int i)
 		);
 }
 
+uint4 BakeData::differentials(int i)
+{
+	return make_uint4(
+		  __float_as_int(m_dudx[i]),
+		  __float_as_int(m_dudy[i]),
+		  __float_as_int(m_dvdx[i]),
+		  __float_as_int(m_dvdy[i])
+		  );
+}
+
 BakeManager::BakeManager()
 {
 	m_bake_data = NULL;
@@ -102,11 +124,12 @@ bool BakeManager::bake(Device *device, DeviceScene *dscene, Scene *scene, Progre
 
 	/* setup input for device task */
 	device_vector<uint4> d_input;
-	uint4 *d_input_data = d_input.resize(limit);
+	uint4 *d_input_data = d_input.resize(limit * 2);
 	size_t d_input_size = 0;
 
 	for(size_t i = 0; i < limit; i++) {
 		d_input_data[d_input_size++] = bake_data->data(i);
+		d_input_data[d_input_size++] = bake_data->differentials(i);
 	}
 
 	if(d_input_size == 0)
@@ -114,7 +137,7 @@ bool BakeManager::bake(Device *device, DeviceScene *dscene, Scene *scene, Progre
 
 	/* run device task */
 	device_vector<float4> d_output;
-	d_output.resize(d_input_size);
+	d_output.resize(limit);
 
 	/* needs to be up to data for attribute access */
 	device->const_copy_to("__data", &dscene->data, sizeof(dscene->data));

intern/cycles/render/bake.h

@@ -29,10 +29,11 @@ public:
 	BakeData(const int object, const int tri_offset, const int num_pixels);
 	~BakeData();
 
-	void set(int i, int prim, float uv[2]);
+	void set(int i, int prim, float uv[2], float dudx, float dudy, float dvdx, float dvdy);
 	int object();
 	int size();
 	uint4 data(int i);
+	uint4 differentials(int i);
 	bool is_valid(int i);
 
 private:
@@ -42,6 +43,10 @@ private:
 	vector<int>m_primitive;
 	vector<float>m_u;
 	vector<float>m_v;
+	vector<float>m_dudx;
+	vector<float>m_dudy;
+	vector<float>m_dvdx;
+	vector<float>m_dvdy;
 };
 
 class BakeManager {