Finish 2D dynamic level set

taichi-dev · Apr 6, 2017 · e151d37 · e151d37
1 parent 1d8c85b
commit e151d37
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Showing 4 changed files with 108 additions and 4 deletions.
diff --git a/include/taichi/math/dynamic_levelset_2d.cpp b/include/taichi/math/dynamic_levelset_2d.cpp
@@ -0,0 +1,49 @@
+/*******************************************************************************
+    Taichi - Physically based Computer Graphics Library
+
+    Copyright (c) 2017 Yu Fang <squarefk@gmail.com>
+
+    All rights reserved. Use of this source code is governed by
+    the MIT license as written in the LICENSE file.
+*******************************************************************************/
+
+#include "dynamic_levelset_2d.h"
+
+TC_NAMESPACE_BEGIN
+
+void DynamicLevelSet2D::initialize(real _t0, real _t1, const LevelSet2D &_ls0, const LevelSet2D &_ls1) {
+    t0 = _t0;
+    t1 = _t1;
+    levelset0 = std::make_shared<LevelSet2D>(_ls0);
+    levelset1 = std::make_shared<LevelSet2D>(_ls1);
+}
+
+Vector2 DynamicLevelSet2D::get_spatial_gradient(const Vector2 &pos, real t) {
+    Vector2 gxy0 = levelset0->get_gradient(pos);
+    Vector2 gxy1 = levelset1->get_gradient(pos);
+    real gx = lerp((t - t0) / (t1 - t0), gxy0.x, gxy1.x);
+    real gy = lerp((t - t0) / (t1 - t0), gxy0.y, gxy1.y);
+    return Vector2(gx, gy);
+}
+
+real DynamicLevelSet2D::get_temporal_gradient(const Vector2 &pos, real t) {
+    real l1 = levelset0->get(pos);
+    real l2 = levelset1->get(pos);
+    return (l2 - l1) / (t1 - t0);
+}
+
+Array2D<real> DynamicLevelSet2D::rasterize(int width, int height, real t) {
+    Array2D<real> r0 = levelset0->rasterize(width, height);
+    Array2D<real> r1 = levelset1->rasterize(width, height);
+    Array2D<real> out(width, height);
+    for (auto &ind : Region2D(0, width, 0, height, Vector2(0.5f, 0.5f))) {
+        out[ind] = lerp((t - t0) / (t1 - t0), r0[ind], r1[ind]);
+        if (std::isnan(out[ind])) {
+            out[ind] = std::numeric_limits<real>::infinity();
+        }
+    }
+    return out;
+}
+
+
+TC_NAMESPACE_END
diff --git a/include/taichi/math/dynamic_levelset_2d.h b/include/taichi/math/dynamic_levelset_2d.h
@@ -0,0 +1,35 @@
+/*******************************************************************************
+    Taichi - Physically based Computer Graphics Library
+
+    Copyright (c) 2017 Yu Fang <squarefk@gmail.com>
+
+    All rights reserved. Use of this source code is governed by
+    the MIT license as written in the LICENSE file.
+*******************************************************************************/
+
+#pragma once
+
+
+#include <limits>
+#include <memory>
+#include <taichi/math/levelset_2d.h>
+
+
+TC_NAMESPACE_BEGIN
+
+class DynamicLevelSet2D {
+    public:
+        real t0, t1;
+        std::shared_ptr<LevelSet2D> levelset0, levelset1;
+
+        void initialize(real _t0, real _t1, const LevelSet2D &_ls0, const LevelSet2D &_ls1);
+
+        Vector2 get_spatial_gradient(const Vector2 &pos, real t);
+
+        real get_temporal_gradient(const Vector2 &pos, real t);
+
+        Array2D<real> rasterize(int width, int height, real t);
+    };
+
+TC_NAMESPACE_END
+
diff --git a/include/taichi/math/levelset_2d.cpp b/include/taichi/math/levelset_2d.cpp
@@ -2,6 +2,7 @@
     Taichi - Physically based Computer Graphics Library
 
     Copyright (c) 2016 Yuanming Hu <yuanmhu@gmail.com>
+                  2017 Yu Fang <squarefk@gmail.com>
 
     All rights reserved. Use of this source code is governed by
     the MIT license as written in the LICENSE file.
@@ -16,7 +17,7 @@ void LevelSet2D::add_sphere(Vector2 center, real radius, bool inside_out) {
     for (auto &ind : get_region()) {
         Vector2 sample = ind.get_pos();
         real dist = (inside_out ? -1 : 1) * (length(center - sample) - radius);
-        set(ind, std::min(get(ind), dist));
+        set(ind, std::min(Array2D::get(ind), dist));
     }
 }
 
@@ -25,7 +26,7 @@ void LevelSet2D::add_polygon(std::vector<Vector2> polygon, bool inside_out)
     for (auto &ind : get_region()) {
         Vector2 p = ind.get_pos();
         real dist = ((inside_polygon(p, polygon) ^ inside_out) ? -1 : 1) * (nearest_distance(p, polygon));
-        set(ind, std::min(get(ind), dist));
+        set(ind, std::min(Array2D::get(ind), dist));
     }
 }
 
@@ -39,8 +40,8 @@ Vector2 LevelSet2D::get_gradient(const Vector2 &pos) const
     const int y_i = clamp(int(y), 0, height - 2);
     const real x_r = x - x_i;
     const real y_r = y - y_i;
-    const real gx = lerp(y_r, get(x_i + 1, y_i) - get(x_i, y_i), get(x_i + 1, y_i + 1) - get(x_i, y_i + 1));
-    const real gy = lerp(x_r, get(x_i, y_i + 1) - get(x_i, y_i), get(x_i + 1, y_i + 1) - get(x_i + 1, y_i));
+    const real gx = lerp(y_r, Array2D::get(x_i + 1, y_i) - Array2D::get(x_i, y_i), Array2D::get(x_i + 1, y_i + 1) - Array2D::get(x_i, y_i + 1));
+    const real gy = lerp(x_r, Array2D::get(x_i, y_i + 1) - Array2D::get(x_i, y_i), Array2D::get(x_i + 1, y_i + 1) - Array2D::get(x_i + 1, y_i));
     return Vector2(gx, gy);
 }
 
@@ -53,6 +54,22 @@ Vector2 LevelSet2D::get_normalized_gradient(const Vector2 &pos) const
         return normalize(gradient);
 }
 
+real LevelSet2D::get(const Vector2 &pos) const
+{
+    assert_info(inside(pos), "LevelSet Gradient Query out of Bound! (" + std::to_string(pos.x) + ", " + std::to_string(pos.y) + ")");
+    real x = pos.x, y = pos.y;
+    x = clamp(x - storage_offset.x, 0.f, width - 1.f - eps);
+    y = clamp(y - storage_offset.y, 0.f, height - 1.f - eps);
+    const int x_i = clamp(int(x), 0, width - 2);
+    const int y_i = clamp(int(y), 0, height - 2);
+    const real x_r = x - x_i;
+    const real y_r = y - y_i;
+    const real ly0 = lerp(x_r, Array2D::get(x_i, y_i), Array2D::get(x_i + 1, y_i));
+    const real ly1 = lerp(x_r, Array2D::get(x_i, y_i + 1), Array2D::get(x_i + 1, y_i + 1));
+    return lerp(y_r, ly0, ly1);
+}
+
+
 Array2D<real> LevelSet2D::rasterize(int width, int height) {
     for (auto &p : (*this)) {
         if (std::isnan(p)) {

diff --git a/include/taichi/math/levelset_2d.h b/include/taichi/math/levelset_2d.h
@@ -2,6 +2,7 @@
     Taichi - Physically based Computer Graphics Library
 
     Copyright (c) 2016 Yuanming Hu <yuanmhu@gmail.com>
+                  2017 Yu Fang <squarefk@gmail.com>
 
     All rights reserved. Use of this source code is governed by
     the MIT license as written in the LICENSE file.
@@ -49,6 +50,8 @@ class LevelSet2D : public Array2D<real> {
 
     Vector2 get_normalized_gradient(const Vector2 &pos) const;
 
+    real get(const Vector2 &pos) const;
+
     static real fraction_outside(real phi_a, real phi_b) {
         return 1.0f - fraction_inside(phi_a, phi_b);
     }