From e1f614101f9d0bbfe9be099863601e58ff069b81 Mon Sep 17 00:00:00 2001
From: EvilSpirit <anandamide@mail.ru>
Date: Thu, 28 Apr 2016 17:10:36 +0600
Subject: [PATCH] Only generate split triangles when exporting if needed.

Before this commit, when exporting a vector file without the shaded
model shown, or similarly when using formats that we do not export
the mesh to, we still generate (and then discard) the mesh in paint
order. This is a waste of time.
---
 src/export.cpp   | 33 ++++++++++++++++-----------------
 src/solvespace.h |  7 +++++--
 2 files changed, 21 insertions(+), 19 deletions(-)

diff --git a/src/export.cpp b/src/export.cpp
index b6baa9a5..9c99a3a4 100644
--- a/src/export.cpp
+++ b/src/export.cpp
@@ -304,20 +304,25 @@ void SolveSpaceUI::ExportLinesAndMesh(SEdgeList *sel, SBezierList *sbl, SMesh *s
         }
     }
 
-    // Use the BSP routines to generate the split triangles in paint order.
-    SBsp3 *bsp = SBsp3::FromMesh(&smp);
     SMesh sms = {};
-    if(bsp) bsp->GenerateInPaintOrder(&sms);
-    // And cull the back-facing triangles
-    STriangle *tr;
-    sms.l.ClearTags();
-    for(tr = sms.l.First(); tr; tr = sms.l.NextAfter(tr)) {
-        Vector n = tr->Normal();
-        if(n.z < 0) {
-            tr->tag = 1;
+
+    // We need the mesh for occlusion testing, but if we don't/can't export it,
+    // don't generate it.
+    if(SS.GW.showShaded && out->CanOutputMesh()) {
+        // Use the BSP routines to generate the split triangles in paint order.
+        SBsp3 *bsp = SBsp3::FromMesh(&smp);
+        if(bsp) bsp->GenerateInPaintOrder(&sms);
+        // And cull the back-facing triangles
+        STriangle *tr;
+        sms.l.ClearTags();
+        for(tr = sms.l.First(); tr; tr = sms.l.NextAfter(tr)) {
+            Vector n = tr->Normal();
+            if(n.z < 0) {
+                tr->tag = 1;
+            }
         }
+        sms.l.RemoveTagged();
     }
-    sms.l.RemoveTagged();
 
     // And now we perform hidden line removal if requested
     SEdgeList hlrd = {};
@@ -516,12 +521,6 @@ void SolveSpaceUI::ExportLinesAndMesh(SEdgeList *sel, SBezierList *sbl, SMesh *s
         sblss.AddOpenPath(b);
     }
 
-    // We need the mesh for occlusion testing, but if we don't export it,
-    // erase it now.
-    if(!SS.GW.showShaded) {
-        sms.Clear();
-    }
-
     // Now write the lines and triangles to the output file
     out->OutputLinesAndMesh(&sblss, &sms);
 
diff --git a/src/solvespace.h b/src/solvespace.h
index c92b08bc..757c3ff3 100644
--- a/src/solvespace.h
+++ b/src/solvespace.h
@@ -500,8 +500,8 @@ public:
     void BezierAsPwl(SBezier *sb);
     void BezierAsNonrationalCubic(SBezier *sb, int depth=0);
 
-    virtual bool OutputConstraints(IdList<Constraint,hConstraint> *constraint)
-        { return false; }
+    virtual bool OutputConstraints(IdList<Constraint,hConstraint> *constraint) { return false; }
+    virtual bool CanOutputMesh() const { return false; }
 
     virtual void StartPath( RgbaColor strokeRgb, double lineWidth,
                             bool filled, RgbaColor fillRgb, hStyle hs) = 0;
@@ -549,6 +549,7 @@ public:
     void StartFile(void);
     void FinishAndCloseFile(void);
     bool HasCanvasSize(void) { return true; }
+    bool CanOutputMesh() const { return true; }
 };
 class PdfFileWriter : public VectorFileWriter {
 public:
@@ -566,6 +567,7 @@ public:
     void StartFile(void);
     void FinishAndCloseFile(void);
     bool HasCanvasSize(void) { return true; }
+    bool CanOutputMesh() const { return true; }
 };
 class SvgFileWriter : public VectorFileWriter {
 public:
@@ -581,6 +583,7 @@ public:
     void StartFile(void);
     void FinishAndCloseFile(void);
     bool HasCanvasSize(void) { return true; }
+    bool CanOutputMesh() const { return true; }
 };
 class HpglFileWriter : public VectorFileWriter {
 public: