From 2afd6103d97b88f8cfd52109de3e7cf06c95b2aa Mon Sep 17 00:00:00 2001
From: phkahler <14852918+phkahler@users.noreply.github.com>
Date: Thu, 1 Oct 2020 00:05:33 -0400
Subject: [PATCH] Add STL linking with bounding box and edge verticies.
 Experimental.

---
 src/CMakeLists.txt   |   1 +
 src/file.cpp         |   4 +-
 src/importmesh.cpp   | 222 +++++++++++++++++++++++++++++++++++++++++++
 src/platform/gui.cpp |   1 +
 src/solvespace.h     |   1 +
 5 files changed, 228 insertions(+), 1 deletion(-)
 create mode 100644 src/importmesh.cpp

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 5ac7b41..ec39939 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -176,6 +176,7 @@ set(solvespace_core_SOURCES
     groupmesh.cpp
     importdxf.cpp
     importidf.cpp
+    importmesh.cpp
     mesh.cpp
     modify.cpp
     mouse.cpp
diff --git a/src/file.cpp b/src/file.cpp
index 4e3b50d..c898972 100644
--- a/src/file.cpp
+++ b/src/file.cpp
@@ -710,7 +710,9 @@ bool SolveSpaceUI::LoadEntitiesFromFile(const Platform::Path &filename, EntityLi
                                         SMesh *m, SShell *sh)
 {
     if(strcmp(filename.Extension().c_str(), "emn")==0) {
-        return LinkIDF(filename, le, m, sh);    
+        return LinkIDF(filename, le, m, sh);
+    } else if(strcmp(filename.Extension().c_str(), "stl")==0) {
+        return LinkStl(filename, le, m, sh);    
     } else {
         return LoadEntitiesFromSlvs(filename, le, m, sh);
     }
diff --git a/src/importmesh.cpp b/src/importmesh.cpp
new file mode 100644
index 0000000..2115175
--- /dev/null
+++ b/src/importmesh.cpp
@@ -0,0 +1,222 @@
+//-----------------------------------------------------------------------------
+// Triangle mesh file reader. Reads an STL file triangle mesh and creates
+// a SovleSpace SMesh from it. Supports only Linking, not import.
+//
+// Copyright 2020 Paul Kahler.
+//-----------------------------------------------------------------------------
+#include "solvespace.h"
+#include "sketch.h"
+#include <vector>
+
+#define MIN_POINT_DISTANCE 0.001
+
+// we will check for duplicate verticies and keep all their normals
+class vertex {
+public:
+    Vector p;
+    std::vector<Vector> normal;
+};
+
+static bool isEdgeVertex(vertex &v) {
+    unsigned int i,j;
+    bool result = false;
+    for(i=0;i<v.normal.size();i++) {
+        for(j=i;j<v.normal.size();j++) {
+            if(v.normal[i].Dot(v.normal[j]) < 0.9) {
+                result = true;
+            }
+        }
+    }
+    return result;
+}
+// This function has poor performance, used inside a loop it is O(n**2)
+static void addUnique(std::vector<vertex> &lv, Vector &p, Vector &n) {
+    unsigned int i;
+    for(i=0; i<lv.size(); i++) {
+        if(lv[i].p.Equals(p, MIN_POINT_DISTANCE)) {
+            break;
+        }
+    }
+    if(i==lv.size()) {
+        vertex v;
+        v.p = p;
+        lv.push_back(v);
+    }
+    // we could improve a little by only storing unique normals
+    lv[i].normal.push_back(n);
+};
+
+// Make a new point - type doesn't matter since we will make a copy later
+static hEntity newPoint(EntityList *el, int id, Vector p) {
+    Entity en = {};
+    en.type = Entity::Type::POINT_N_COPY;
+    en.extraPoints = 0;
+    en.timesApplied = 0;
+    en.group.v = 462;
+    en.actPoint = p;
+    en.construction = false;
+    en.style.v = Style::DATUM;
+    en.actVisible = true;
+    en.forceHidden = false;
+
+    en.h.v = id + en.group.v*65536;    
+    el->Add(&en);
+    return en.h;
+}
+
+// check if a vertex is unique and add it via newPoint if it is.
+static void addVertex(EntityList *el, Vector v) {
+    if(el->n < 15000) {
+        int id = el->n+2;
+        newPoint(el, id, v);
+    }
+}
+
+static hEntity newLine(EntityList *el, int id, hEntity p0, hEntity p1) {
+    Entity en = {};
+    en.type = Entity::Type::LINE_SEGMENT;
+    en.point[0] = p0;
+    en.point[1] = p1;
+    en.extraPoints = 0;
+    en.timesApplied = 0;
+    en.group.v = 493;
+    en.construction = true;
+    en.style.v = Style::CONSTRUCTION;
+    en.actVisible = true;
+    en.forceHidden = false;
+
+    en.h.v = id + en.group.v*65536;
+    el->Add(&en);
+    return en.h;
+}
+
+namespace SolveSpace {
+
+bool LinkStl(const Platform::Path &filename, EntityList *el, SMesh *m, SShell *sh) {
+    dbp("\nLink STL triangle mesh.");
+    el->Clear();
+    std::string data;
+    if(!ReadFile(filename, &data)) {
+        Error("Couldn't read from '%s'", filename.raw.c_str());
+        return false;
+    }
+    
+    std::stringstream f(data);
+
+    char str[80] = {};
+    f.read(str, 80);
+    
+    uint32_t n;
+    uint32_t color;
+    
+    f.read((char*)&n, 4);
+    dbp("%d triangles", n);
+    
+    float x,y,z;
+    float xn,yn,zn;
+    
+    //add the STL origin as an entity
+    addVertex(el, Vector::From(0.0, 0.0, 0.0));
+    
+    std::vector<vertex> verts = {};
+    
+    for(uint32_t i = 0; i<n; i++) {
+        STriangle tr = {};
+
+        // read the triangle normal
+        f.read((char*)&xn, 4);
+        f.read((char*)&yn, 4);
+        f.read((char*)&zn, 4);
+        tr.an = Vector::From(xn,yn,zn);
+        tr.bn = tr.an;
+        tr.cn = tr.an;
+
+        f.read((char*)&x, 4);
+        f.read((char*)&y, 4);
+        f.read((char*)&z, 4);
+        tr.a.x = x;
+        tr.a.y = y;
+        tr.a.z = z;
+
+        f.read((char*)&x, 4);
+        f.read((char*)&y, 4);
+        f.read((char*)&z, 4);
+        tr.b.x = x;
+        tr.b.y = y;
+        tr.b.z = z;
+
+        f.read((char*)&x, 4);
+        f.read((char*)&y, 4);
+        f.read((char*)&z, 4);
+        tr.c.x = x;
+        tr.c.y = y;
+        tr.c.z = z;
+
+        f.read((char*)&color,2);
+        if(color & 0x8000) {
+            tr.meta.color.red = (color >> 7) & 0xf8;
+            tr.meta.color.green = (color >> 2) & 0xf8;
+            tr.meta.color.blue = (color << 3);
+            tr.meta.color.alpha = 255;
+        } else {
+            tr.meta.color.red = 90;
+            tr.meta.color.green = 120;
+            tr.meta.color.blue = 140;
+            tr.meta.color.alpha = 255;        
+        }
+
+        m->AddTriangle(&tr);
+        Vector normal = tr.Normal().WithMagnitude(1.0);
+        addUnique(verts, tr.a, normal);
+        addUnique(verts, tr.b, normal);
+        addUnique(verts, tr.c, normal);
+    }
+    SK.GetGroup(SS.GW.activeGroup)->forceToMesh = true;
+    dbp("%d verticies", verts.size());
+
+    BBox box = {};
+    box.minp = verts[0].p;
+    box.maxp = verts[0].p;
+
+    // determine the bounding box for all vertexes
+    for(unsigned int i=1; i<verts.size(); i++) {
+        box.Include(verts[i].p);
+    }
+
+    hEntity p[8];
+    int id = el->n+2;
+    p[0] = newPoint(el, id++, Vector::From(box.minp.x, box.minp.y, box.minp.z));
+    p[1] = newPoint(el, id++, Vector::From(box.maxp.x, box.minp.y, box.minp.z));
+    p[2] = newPoint(el, id++, Vector::From(box.minp.x, box.maxp.y, box.minp.z));
+    p[3] = newPoint(el, id++, Vector::From(box.maxp.x, box.maxp.y, box.minp.z));
+    p[4] = newPoint(el, id++, Vector::From(box.minp.x, box.minp.y, box.maxp.z));
+    p[5] = newPoint(el, id++, Vector::From(box.maxp.x, box.minp.y, box.maxp.z));
+    p[6] = newPoint(el, id++, Vector::From(box.minp.x, box.maxp.y, box.maxp.z));
+    p[7] = newPoint(el, id++, Vector::From(box.maxp.x, box.maxp.y, box.maxp.z));
+
+    newLine(el, id++, p[0], p[1]);
+    newLine(el, id++, p[0], p[2]);
+    newLine(el, id++, p[3], p[1]);
+    newLine(el, id++, p[3], p[2]);
+
+    newLine(el, id++, p[4], p[5]);
+    newLine(el, id++, p[4], p[6]);
+    newLine(el, id++, p[7], p[5]);
+    newLine(el, id++, p[7], p[6]);
+
+    newLine(el, id++, p[0], p[4]);
+    newLine(el, id++, p[1], p[5]);
+    newLine(el, id++, p[2], p[6]);
+    newLine(el, id++, p[3], p[7]);
+    
+    for(unsigned int i=0; i<verts.size(); i++) {
+        // create point entities for edge vertexes
+        if(isEdgeVertex(verts[i])) {
+            addVertex(el, verts[i].p);
+        }
+    }
+
+    return true;
+}
+
+}
diff --git a/src/platform/gui.cpp b/src/platform/gui.cpp
index 28fded4..a685e86 100644
--- a/src/platform/gui.cpp
+++ b/src/platform/gui.cpp
@@ -88,6 +88,7 @@ std::vector<FileFilter> SolveSpaceModelFileFilters = {
 std::vector<FileFilter> SolveSpaceLinkFileFilters = {
     { CN_("file-type", "SolveSpace models"), { "slvs" } },
     { CN_("file-type", "IDF circuit board"), { "emn" } },
+    { CN_("file-type", "STL triangle mesh"), { "stl" } },
 };
 
 std::vector<FileFilter> RasterFileFilters = {
diff --git a/src/solvespace.h b/src/solvespace.h
index e64a1ab..d4caab2 100644
--- a/src/solvespace.h
+++ b/src/solvespace.h
@@ -812,6 +812,7 @@ public:
 void ImportDxf(const Platform::Path &file);
 void ImportDwg(const Platform::Path &file);
 bool LinkIDF(const Platform::Path &filename, EntityList *le, SMesh *m, SShell *sh);
+bool LinkStl(const Platform::Path &filename, EntityList *le, SMesh *m, SShell *sh);
 
 extern SolveSpaceUI SS;
 extern Sketch SK;