MeshDeformer

Author: LunaTheFoxgirl

source/inochi2d/core/math/deform.d

@@ -45,6 +45,17 @@ public:
     */
     void deform(vec2[] deformed, bool absolute = false);
 
+    /**
+        Deforms a single vertex in the IDeformable
+
+        Params:
+            offset =    The offset into the point list to deform.
+            deform =    The deformation delta.
+            absolute =  Whether the deformation is absolute,
+                        replacing the original deformation.
+    */
+    void deform(size_t offset, vec2 deform, bool absolute = false);
+
     /**
         Resets the deformation for the IDeformable.
     */

source/inochi2d/core/math/package.d

@@ -24,6 +24,7 @@ import std.json;
 import numem;
 
 public import inochi2d.core.math.deform;
+public import inochi2d.core.math.trig;
 
 /**
     A camera
@@ -222,26 +223,6 @@ private:
     mat4 trs = mat4.identity;
 }
 
-
-bool isPointInTriangle(vec2 pt, vec2[3] triangle) {
-    float sign (ref vec2 p1, ref vec2 p2, ref vec2 p3) {
-        return (p1.x - p3.x) * (p2.y - p3.y) - (p2.x - p3.x) * (p1.y - p3.y);
-    }
-    vec2 p1 = triangle[0];
-    vec2 p2 = triangle[1];
-    vec2 p3 = triangle[2];
-
-    auto d1 = sign(pt, p1, p2);
-    auto d2 = sign(pt, p2, p3);
-    auto d3 = sign(pt, p3, p1);
-
-    auto hasNeg = (d1 < 0) || (d2 < 0) || (d3 < 0);
-    auto hasPos = (d1 > 0) || (d2 > 0) || (d3 > 0);
-
-    return !(hasNeg && hasPos);
-}
-
-
 int[] findSurroundingTriangle(vec2 pt, ref MeshData bindingMesh) {
     bool isPointInTriangle(vec2 pt, int[] triangle) {
         float sign (ref vec2 p1, ref vec2 p2, ref vec2 p3) {

source/inochi2d/core/math/trig.d

@@ -0,0 +1,82 @@
+/**
+    Inochi2D Triangles and trigonometry
+
+    Copyright © 2020-2025, Inochi2D Project
+    Distributed under the 2-Clause BSD License, see LICENSE file.
+    
+    Authors: Luna Nielsen
+*/
+module inochi2d.core.math.trig;
+import inmath.linalg;
+
+/**
+    A 2D triangle
+*/
+struct Triangle {
+@nogc:
+    vec2 p1;
+    vec2 p2;
+    vec2 p3;
+
+    /**
+        Gets the barycentric coordinates of the given point.
+
+        Params:
+            pt = The point to check.
+
+        Returns:
+            The barycentric coordinates in relation to each
+            vertex of the triangle.
+    */
+    pragma(inline, true)
+    vec3 barycentric(vec2 pt) nothrow pure {
+        vec2 v1 = p2 - p1;
+        vec2 v2 = p3 - p1;
+        vec2 v3 = pt - p1;
+        float den = v1.x * v2.y - v2.x * v1.y;
+        float v = (v3.x * v2.y - v2.x * v3.y) / den;
+        float w = (v1.x * v3.y - v3.x * v1.y) / den;
+        return vec3(
+            1.0 - v - w,
+            v,
+            w,
+        );
+    }
+
+    /**
+        Whether the triangle contains the given point.
+
+        Params:
+            pt = The point to check.
+        
+        Returns:
+            $(D true) if the given point lies within this
+            triangle, $(D false) otherwise.
+    */
+    pragma(inline, true)
+    bool contains(vec2 pt) nothrow pure {
+        float d1 = sign(pt, p1, p2);
+        float d2 = sign(pt, p2, p3);
+        float d3 = sign(pt, p3, p1);
+        return !(
+            ((d1 < 0) || (d2 < 0) || (d3 < 0)) &&
+            ((d1 > 0) || (d2 > 0) || (d3 > 0))
+        );
+    }
+}
+
+/**
+    Gets the sign between 3 points.
+
+    Params:
+        p1 = The first point
+        p2 = The second point
+        p3 = The third point.
+    
+    Returns:
+        A float determining the sign between p1, p2 and p3.
+*/
+pragma(inline, true)
+float sign (ref vec2 p1, ref vec2 p2, ref vec2 p3) @nogc nothrow pure {
+    return (p1.x - p3.x) * (p2.y - p3.y) - (p2.x - p3.x) * (p1.y - p3.y);
+}