Commit: 6a535b7b184357e33e7ad4ebfb5e0a524e7ebff6
Author: Lukas Tönne
Date: Thu Jan 8 10:45:20 2015 +0100
Branches: temp_hair_flow
https://developer.blender.org/rB6a535b7b184357e33e7ad4ebfb5e0a524e7ebff6
Gradient calculation and normalization from the pressure field.
===================================================================
M source/blender/physics/intern/grid.cpp
M source/blender/physics/intern/grid.h
M source/blender/physics/intern/hair_flow.cpp
===================================================================
diff --git a/source/blender/physics/intern/grid.cpp
b/source/blender/physics/intern/grid.cpp
index ff188f0..0fc8917 100644
--- a/source/blender/physics/intern/grid.cpp
+++ b/source/blender/physics/intern/grid.cpp
@@ -66,19 +66,14 @@ void Grid::resize(float _cellsize, const float _offset[3],
const int _res[3])
copy_v3_v3(offset, _offset);
copy_v3_v3_int(res, _res);
num_cells = _res[0] * _res[1] * _res[2];
-
- divergence.resize(num_cells);
- pressure.resize(num_cells);
}
void Grid::init()
{
- divergence.setZero();
}
void Grid::clear()
{
- pressure.setZero();
}
int Grid::set_inner_cells(GridHash<bool> &bounds, GridHash<float3> &normal,
Object *ob) const
@@ -224,6 +219,54 @@ void Grid::calc_divergence(GridHash<float> &divergence,
const GridHash<bool> &so
}
}
+/* Calculate velocity = grad(p) */
+void Grid::calc_gradient(GridHash<float3> &velocity, const GridHash<float>
&pressure) const
+{
+ const float inv_flowfac = 1.0f / cellsize;
+
+ velocity.clear();
+
+ for (int z = 0; z < res[2]; ++z) {
+ for (int y = 0; y < res[1]; ++y) {
+ for (int x = 0; x < res[0]; ++x) {
+ bool is_margin = !(x > 0 && x < res[0]-1 && y >
0 && y < res[1]-1 && z > 0 && z < res[2]-1);
+ if (is_margin)
+ continue;
+
+ /*const float *p = pressure.get(x, y, z);*/
+ const float *pl = pressure.get(x-1, y, z);
+ const float *pr = pressure.get(x+1, y, z);
+ const float *pb = pressure.get(x, y-1, z);
+ const float *pt = pressure.get(x, y+1, z);
+ const float *pd = pressure.get(x, y, z-1);
+ const float *pu = pressure.get(x, y, z+1);
+
+ /* finite difference estimate of pressure
gradient */
+ float dvel[3];
+ dvel[0] = *pr - *pl;
+ dvel[1] = *pt - *pb;
+ dvel[2] = *pu - *pd;
+ mul_v3_fl(dvel, -0.5f * inv_flowfac);
+
+ velocity.add(x, y, z) = float3(dvel);
+ }
+ }
+ }
+}
+
+void Grid::normalize(GridHash<float3> &velocity) const
+{
+ for (int z = 0; z < res[2]; ++z) {
+ for (int y = 0; y < res[1]; ++y) {
+ for (int x = 0; x < res[0]; ++x) {
+ float3 *v = velocity.get(x, y, z);
+ if (v)
+ normalize_v3(*v);
+ }
+ }
+ }
+}
+
/* Main Poisson equation system:
* This is derived from the discretezation of the Poisson equation
* div(grad(p)) = div(v)
@@ -234,7 +277,7 @@ void Grid::calc_divergence(GridHash<float> &divergence,
const GridHash<bool> &so
* For a good overview of eulerian fluid sim methods, see
*
http://www.proxyarch.com/util/techpapers/papers/Fluid%20flow%20for%20the%20rest%20of%20us.pdf
*/
-void Grid::solve_pressure(GridHash<float> &pressure, const GridHash<float>
&divergence)
+void Grid::solve_pressure(GridHash<float> &pressure, const GridHash<float>
&divergence) const
{
int stride[3] = { 1, res[0], res[0] * res[1] };
diff --git a/source/blender/physics/intern/grid.h
b/source/blender/physics/intern/grid.h
index 206225f..0b39f02 100644
--- a/source/blender/physics/intern/grid.h
+++ b/source/blender/physics/intern/grid.h
@@ -140,18 +140,18 @@ typedef struct Grid {
void clear();
int set_inner_cells(GridHash<bool> &bounds, GridHash<float3> &normal,
struct Object *ob) const;
+
void calc_divergence(GridHash<float> &divergence, const GridHash<bool>
&source, const GridHash<float3> &source_normal) const;
+ void calc_gradient(GridHash<float3> &velocity, const GridHash<float>
&pressure) const;
+ void normalize(GridHash<float3> &velocity) const;
- void solve_pressure(GridHash<float> &pressure, const GridHash<float>
&divergence);
+ void solve_pressure(GridHash<float> &pressure, const GridHash<float>
&divergence) const;
float cellsize, inv_cellsize;
float offset[3];
int res[3];
int num_cells;
- lVector divergence;
- lVector pressure;
-
struct SimDebugData *debug_data;
float debug1, debug2;
int debug3, debug4;
diff --git a/source/blender/physics/intern/hair_flow.cpp
b/source/blender/physics/intern/hair_flow.cpp
index e0c0696..dcf7ca7 100644
--- a/source/blender/physics/intern/hair_flow.cpp
+++ b/source/blender/physics/intern/hair_flow.cpp
@@ -148,6 +148,11 @@ HairFlowData *BPH_strands_solve_hair_flow(Scene *scene,
Object *ob, float max_le
pressure.resize(data->grid.res);
data->grid.solve_pressure(pressure, divergence);
+ GridHash<float3> velocity;
+ velocity.resize(data->grid.res);
+ data->grid.calc_gradient(velocity, pressure);
+ data->grid.normalize(velocity);
+
{
float col0[3] = {0.0, 0.0, 0.0};
float colp[3] = {0.0, 1.0, 1.0};
@@ -185,6 +190,8 @@ HairFlowData *BPH_strands_solve_hair_flow(Scene *scene,
Object *ob, float max_le
}
if (fac > 0.05f)
BKE_sim_debug_data_add_circle(debug_data, vec, 0.02f, col[0], col[1], col[2],
"hair_flow", 5522, x, y, z);
+
+
BKE_sim_debug_data_add_vector(debug_data, vec, *velocity.get(x, y, z), 1,1,0,
"hair_flow", 957, x, y, z);
}
}
}
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