From 7715310afe244d74744de16add9520726ee1e339 Mon Sep 17 00:00:00 2001
From: Eric Wasylishen <ewasylishen@gmail.com>
Date: Thu, 19 May 2016 22:02:45 -0600
Subject: [PATCH] common: add AllocWindingEdges, FreeWindingEdges,
 PointInWindingEdges

---
 common/polylib.c         | 50 ++++++++++++++++++++++++++++++++++++++++
 include/common/polylib.h |  9 ++++++++
 2 files changed, 59 insertions(+)

diff --git a/common/polylib.c b/common/polylib.c
index 91b32de0..4125ab0a 100644
--- a/common/polylib.c
+++ b/common/polylib.c
@@ -503,3 +503,53 @@ winding_t *WindingFromFace (const bsp2_t *bsp, const bsp2_dface_t *f)
     
     return w;
 }
+
+winding_edges_t *
+AllocWindingEdges(const winding_t *w)
+{
+    plane_t p;
+    WindingPlane(w, p.normal, &p.dist);
+    
+    winding_edges_t *result = (winding_edges_t *) calloc(1, sizeof(winding_edges_t));
+    result->numedges = w->numpoints;
+    result->planes = (plane_t *) calloc(w->numpoints, sizeof(plane_t));
+    
+    for (int i=0; i<w->numpoints; i++)
+    {
+        plane_t *dest = &result->planes[i];
+        
+        const vec_t *v0 = w->p[i];
+        const vec_t *v1 = w->p[(i+1)%w->numpoints];
+        
+        vec3_t edgevec;
+        VectorSubtract(v1, v0, edgevec);
+        VectorNormalize(edgevec);
+        
+        CrossProduct(edgevec, p.normal, dest->normal);
+        dest->dist = DotProduct(dest->normal, v0);
+    }
+    
+    return result;
+}
+
+void
+FreeWindingEdges(winding_edges_t *wi)
+{
+    free(wi->planes);
+    free(wi);
+}
+
+bool
+PointInWindingEdges(const winding_edges_t *wi, const vec3_t point)
+{
+    for (int i=0; i<wi->numedges; i++)
+    {
+        /* faces toward the center of the face */
+        const plane_t *edgeplane = &wi->planes[i];
+        
+        vec_t dist = DotProduct(point, edgeplane->normal) - edgeplane->dist;
+        if (dist < 0)
+            return false;
+    }
+    return true;
+}
diff --git a/include/common/polylib.h b/include/common/polylib.h
index 43962af5..c34375d2 100644
--- a/include/common/polylib.h
+++ b/include/common/polylib.h
@@ -15,6 +15,11 @@ typedef struct {
     vec3_t p[4];                /* variable sized */
 } winding_t;
 
+typedef struct {
+    int numedges;
+    plane_t *planes;
+} winding_edges_t;
+    
 #define MAX_POINTS_ON_WINDING 64
 #define ON_EPSILON 0.1
 
@@ -35,6 +40,10 @@ typedef void (*save_winding_fn_t)(winding_t *w);
 void DiceWinding (winding_t *w, vec_t subdiv, save_winding_fn_t save_fn);
     
 winding_t *WindingFromFace (const bsp2_t *bsp, const bsp2_dface_t *f);
+
+winding_edges_t *AllocWindingEdges(const winding_t *w);
+void FreeWindingEdges(winding_edges_t *wi);
+bool PointInWindingEdges(const winding_edges_t *wi, const vec3_t point);
     
 #ifdef __cplusplus
 }