//----------------------------------------------------------------------------- // The 2d vector output stuff that isn't specific to any particular file // format: getting the appropriate lines and curves, performing hidden line // removal, calculating bounding boxes, and so on. Also raster and triangle // mesh output. //----------------------------------------------------------------------------- #include "solvespace.h" #include void SolveSpace::ExportSectionTo(char *filename) { Vector gn = (SS.GW.projRight).Cross(SS.GW.projUp); gn = gn.WithMagnitude(1); Group *g = SK.GetGroup(SS.GW.activeGroup); g->GenerateDisplayItems(); if(g->displayMesh.IsEmpty()) { Error("No solid model present; draw one with extrudes and revolves, " "or use Export 2d View to export bare lines and curves."); return; } // The plane in which the exported section lies; need this because we'll // reorient from that plane into the xy plane before exporting. Vector origin, u, v, n; double d; SS.GW.GroupSelection(); #define gs (SS.GW.gs) if((gs.n == 0 && g->activeWorkplane.v != Entity::FREE_IN_3D.v)) { Entity *wrkpl = SK.GetEntity(g->activeWorkplane); origin = wrkpl->WorkplaneGetOffset(); n = wrkpl->Normal()->NormalN(); u = wrkpl->Normal()->NormalU(); v = wrkpl->Normal()->NormalV(); } else if(gs.n == 1 && gs.faces == 1) { Entity *face = SK.GetEntity(gs.entity[0]); origin = face->FaceGetPointNum(); n = face->FaceGetNormalNum(); if(n.Dot(gn) < 0) n = n.ScaledBy(-1); u = n.Normal(0); v = n.Normal(1); } else if(gs.n == 3 && gs.vectors == 2 && gs.points == 1) { Vector ut = SK.GetEntity(gs.entity[0])->VectorGetNum(), vt = SK.GetEntity(gs.entity[1])->VectorGetNum(); ut = ut.WithMagnitude(1); vt = vt.WithMagnitude(1); if(fabs(SS.GW.projUp.Dot(vt)) < fabs(SS.GW.projUp.Dot(ut))) { SWAP(Vector, ut, vt); } if(SS.GW.projRight.Dot(ut) < 0) ut = ut.ScaledBy(-1); if(SS.GW.projUp. Dot(vt) < 0) vt = vt.ScaledBy(-1); origin = SK.GetEntity(gs.point[0])->PointGetNum(); n = ut.Cross(vt); u = ut.WithMagnitude(1); v = (n.Cross(u)).WithMagnitude(1); } else { Error("Bad selection for export section. Please select:\n\n" " * nothing, with an active workplane " "(workplane is section plane)\n" " * a face (section plane through face)\n" " * a point and two line segments " "(plane through point and parallel to lines)\n"); return; } SS.GW.ClearSelection(); n = n.WithMagnitude(1); d = origin.Dot(n); SEdgeList el; ZERO(&el); SBezierList bl; ZERO(&bl); // If there's a mesh, then grab the edges from it. g->runningMesh.MakeEdgesInPlaneInto(&el, n, d); // If there's a shell, then grab the edges and possibly Beziers. g->runningShell.MakeSectionEdgesInto(n, d, &el, (SS.exportPwlCurves || fabs(SS.exportOffset) > LENGTH_EPS) ? NULL : &bl); // All of these are solid model edges, so use the appropriate style. SEdge *se; for(se = el.l.First(); se; se = el.l.NextAfter(se)) { se->auxA = Style::SOLID_EDGE; } SBezier *sb; for(sb = bl.l.First(); sb; sb = bl.l.NextAfter(sb)) { sb->auxA = Style::SOLID_EDGE; } el.CullExtraneousEdges(); bl.CullIdenticalBeziers(); // And write the edges. VectorFileWriter *out = VectorFileWriter::ForFile(filename); if(out) { // parallel projection (no perspective), and no mesh ExportLinesAndMesh(&el, &bl, NULL, u, v, n, origin, 0, out); } el.Clear(); bl.Clear(); } void SolveSpace::ExportViewOrWireframeTo(char *filename, bool wireframe) { int i; SEdgeList edges; ZERO(&edges); SBezierList beziers; ZERO(&beziers); SMesh *sm = NULL; if(SS.GW.showShaded) { Group *g = SK.GetGroup(SS.GW.activeGroup); g->GenerateDisplayItems(); sm = &(g->displayMesh); } if(sm && sm->IsEmpty()) { sm = NULL; } for(i = 0; i < SK.entity.n; i++) { Entity *e = &(SK.entity.elem[i]); if(!e->IsVisible()) continue; if(e->construction) continue; if(SS.exportPwlCurves || (sm && !SS.GW.showHdnLines) || fabs(SS.exportOffset) > LENGTH_EPS) { // We will be doing hidden line removal, which we can't do on // exact curves; so we need things broken down to pwls. Same // problem with cutter radius compensation. e->GenerateEdges(&edges); } else { e->GenerateBezierCurves(&beziers); } } if(SS.GW.showEdges) { Group *g = SK.GetGroup(SS.GW.activeGroup); g->GenerateDisplayItems(); SEdgeList *selr = &(g->displayEdges); SEdge *se; for(se = selr->l.First(); se; se = selr->l.NextAfter(se)) { edges.AddEdge(se->a, se->b, Style::SOLID_EDGE); } } if(SS.GW.showConstraints) { Constraint *c; for(c = SK.constraint.First(); c; c = SK.constraint.NextAfter(c)) { c->GetEdges(&edges); } } if(wireframe) { VectorFileWriter *out = VectorFileWriter::ForFile(filename); if(out) { ExportWireframeCurves(&edges, &beziers, out); } } else { Vector u = SS.GW.projRight, v = SS.GW.projUp, n = u.Cross(v), origin = SS.GW.offset.ScaledBy(-1); VectorFileWriter *out = VectorFileWriter::ForFile(filename); if(out) { ExportLinesAndMesh(&edges, &beziers, sm, u, v, n, origin, SS.CameraTangent()*SS.GW.scale, out); } if(out && !out->HasCanvasSize()) { // These file formats don't have a canvas size, so they just // get exported in the raw coordinate system. So indicate what // that was on-screen. SS.justExportedInfo.draw = true; SS.justExportedInfo.pt = origin; SS.justExportedInfo.u = u; SS.justExportedInfo.v = v; InvalidateGraphics(); } } edges.Clear(); beziers.Clear(); } void SolveSpace::ExportWireframeCurves(SEdgeList *sel, SBezierList *sbl, VectorFileWriter *out) { SBezierLoopSetSet sblss; ZERO(&sblss); SEdge *se; for(se = sel->l.First(); se; se = sel->l.NextAfter(se)) { SBezier sb = SBezier::From( (se->a).ScaledBy(1.0 / SS.exportScale), (se->b).ScaledBy(1.0 / SS.exportScale)); sblss.AddOpenPath(&sb); } sbl->ScaleSelfBy(1.0/SS.exportScale); SBezier *sb; for(sb = sbl->l.First(); sb; sb = sbl->l.NextAfter(sb)) { sblss.AddOpenPath(sb); } out->Output(&sblss, NULL); sblss.Clear(); } void SolveSpace::ExportLinesAndMesh(SEdgeList *sel, SBezierList *sbl, SMesh *sm, Vector u, Vector v, Vector n, Vector origin, double cameraTan, VectorFileWriter *out) { double s = 1.0 / SS.exportScale; // Project into the export plane; so when we're done, z doesn't matter, // and x and y are what goes in the DXF. SEdge *e; for(e = sel->l.First(); e; e = sel->l.NextAfter(e)) { // project into the specified csys, and apply export scale (e->a) = e->a.InPerspective(u, v, n, origin, cameraTan).ScaledBy(s); (e->b) = e->b.InPerspective(u, v, n, origin, cameraTan).ScaledBy(s); } SBezier *b; if(sbl) { for(b = sbl->l.First(); b; b = sbl->l.NextAfter(b)) { *b = b->InPerspective(u, v, n, origin, cameraTan); int i; for(i = 0; i <= b->deg; i++) { b->ctrl[i] = (b->ctrl[i]).ScaledBy(s); } } } // If cutter radius compensation is requested, then perform it now if(fabs(SS.exportOffset) > LENGTH_EPS) { // assemble those edges into a polygon, and clear the edge list SPolygon sp; ZERO(&sp); sel->AssemblePolygon(&sp, NULL); sel->Clear(); SPolygon compd; ZERO(&compd); sp.normal = Vector::From(0, 0, -1); sp.FixContourDirections(); sp.OffsetInto(&compd, SS.exportOffset*s); sp.Clear(); compd.MakeEdgesInto(sel); compd.Clear(); } // Now the triangle mesh; project, then build a BSP to perform // occlusion testing and generated the shaded surfaces. SMesh smp; ZERO(&smp); if(sm) { Vector l0 = (SS.lightDir[0]).WithMagnitude(1), l1 = (SS.lightDir[1]).WithMagnitude(1); STriangle *tr; for(tr = sm->l.First(); tr; tr = sm->l.NextAfter(tr)) { STriangle tt = *tr; tt.a = (tt.a).InPerspective(u, v, n, origin, cameraTan).ScaledBy(s); tt.b = (tt.b).InPerspective(u, v, n, origin, cameraTan).ScaledBy(s); tt.c = (tt.c).InPerspective(u, v, n, origin, cameraTan).ScaledBy(s); // And calculate lighting for the triangle Vector n = tt.Normal().WithMagnitude(1); double lighting = SS.ambientIntensity + max(0, (SS.lightIntensity[0])*(n.Dot(l0))) + max(0, (SS.lightIntensity[1])*(n.Dot(l1))); double r = min(1, REDf (tt.meta.color)*lighting), g = min(1, GREENf(tt.meta.color)*lighting), b = min(1, BLUEf (tt.meta.color)*lighting); tt.meta.color = RGBf(r, g, b); smp.AddTriangle(&tt); } } // Use the BSP routines to generate the split triangles in paint order. SBsp3 *bsp = SBsp3::FromMesh(&smp); SMesh sms; ZERO(&sms); 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(); // And now we perform hidden line removal if requested SEdgeList hlrd; ZERO(&hlrd); if(sm && !SS.GW.showHdnLines) { SKdNode *root = SKdNode::From(&smp); // Generate the edges where a curved surface turns from front-facing // to back-facing. if(SS.GW.showEdges) { root->MakeCertainEdgesInto(sel, SKdNode::TURNING_EDGES, false, NULL, NULL); } root->ClearTags(); int cnt = 1234; SEdge *se; for(se = sel->l.First(); se; se = sel->l.NextAfter(se)) { if(se->auxA == Style::CONSTRAINT) { // Constraints should not get hidden line removed; they're // always on top. hlrd.AddEdge(se->a, se->b, se->auxA); continue; } SEdgeList out; ZERO(&out); // Split the original edge against the mesh out.AddEdge(se->a, se->b, se->auxA); root->OcclusionTestLine(*se, &out, cnt); // the occlusion test splits unnecessarily; so fix those out.MergeCollinearSegments(se->a, se->b); cnt++; // And add the results to our output SEdge *sen; for(sen = out.l.First(); sen; sen = out.l.NextAfter(sen)) { hlrd.AddEdge(sen->a, sen->b, sen->auxA); } out.Clear(); } sel = &hlrd; } // We kept the line segments and Beziers separate until now; but put them // all together, and also project everything into the xy plane, since not // all export targets ignore the z component of the points. for(e = sel->l.First(); e; e = sel->l.NextAfter(e)) { SBezier sb = SBezier::From(e->a, e->b); sb.auxA = e->auxA; sbl->l.Add(&sb); } for(b = sbl->l.First(); b; b = sbl->l.NextAfter(b)) { for(int i = 0; i <= b->deg; i++) { b->ctrl[i].z = 0; } } // If possible, then we will assemble these output curves into loops. They // will then get exported as closed paths. SBezierLoopSetSet sblss; ZERO(&sblss); SBezierList leftovers; ZERO(&leftovers); SSurface srf = SSurface::FromPlane(Vector::From(0, 0, 0), Vector::From(1, 0, 0), Vector::From(0, 1, 0)); SPolygon spxyz; ZERO(&spxyz); bool allClosed; SEdge notClosedAt; sbl->l.ClearTags(); sblss.FindOuterFacesFrom(sbl, &spxyz, &srf, SS.ChordTolMm()*s, &allClosed, ¬ClosedAt, NULL, NULL, &leftovers); for(b = leftovers.l.First(); b; b = leftovers.l.NextAfter(b)) { sblss.AddOpenPath(b); } // Now write the lines and triangles to the output file out->Output(&sblss, &sms); leftovers.Clear(); spxyz.Clear(); sblss.Clear(); smp.Clear(); sms.Clear(); hlrd.Clear(); } double VectorFileWriter::MmToPts(double mm) { // 72 points in an inch return (mm/25.4)*72; } VectorFileWriter *VectorFileWriter::ForFile(char *filename) { VectorFileWriter *ret; if(StringEndsIn(filename, ".dxf")) { static DxfFileWriter DxfWriter; ret = &DxfWriter; } else if(StringEndsIn(filename, ".ps") || StringEndsIn(filename, ".eps")) { static EpsFileWriter EpsWriter; ret = &EpsWriter; } else if(StringEndsIn(filename, ".pdf")) { static PdfFileWriter PdfWriter; ret = &PdfWriter; } else if(StringEndsIn(filename, ".svg")) { static SvgFileWriter SvgWriter; ret = &SvgWriter; } else if(StringEndsIn(filename, ".plt")||StringEndsIn(filename, ".hpgl")) { static HpglFileWriter HpglWriter; ret = &HpglWriter; } else if(StringEndsIn(filename, ".step")||StringEndsIn(filename, ".stp")) { static Step2dFileWriter Step2dWriter; ret = &Step2dWriter; } else if(StringEndsIn(filename, ".txt")) { static GCodeFileWriter GCodeWriter; ret = &GCodeWriter; } else { Error("Can't identify output file type from file extension of " "filename '%s'; try " ".step, .stp, .dxf, .svg, .plt, .hpgl, .pdf, .txt, " ".eps, or .ps.", filename); return NULL; } FILE *f = fopen(filename, "wb"); if(!f) { Error("Couldn't write to '%s'", filename); return NULL; } ret->f = f; return ret; } static void AddUnregMessageCallback(void *fndata, Vector a, Vector b) { SBezierLoopSetSet *sblss = (SBezierLoopSetSet *)fndata; SBezier sb = SBezier::From(a, b); sb.auxA = Style::SELECTED; sblss->AddOpenPath(&sb); } void VectorFileWriter::Output(SBezierLoopSetSet *sblss, SMesh *sm) { STriangle *tr; SBezier *b; // First calculate the bounding box. ptMin = Vector::From(VERY_POSITIVE, VERY_POSITIVE, VERY_POSITIVE); ptMax = Vector::From(VERY_NEGATIVE, VERY_NEGATIVE, VERY_NEGATIVE); if(sm) { for(tr = sm->l.First(); tr; tr = sm->l.NextAfter(tr)) { (tr->a).MakeMaxMin(&ptMax, &ptMin); (tr->b).MakeMaxMin(&ptMax, &ptMin); (tr->c).MakeMaxMin(&ptMax, &ptMin); } } if(sblss) { SBezierLoopSet *sbls; for(sbls = sblss->l.First(); sbls; sbls = sblss->l.NextAfter(sbls)) { SBezierLoop *sbl; for(sbl = sbls->l.First(); sbl; sbl = sbls->l.NextAfter(sbl)) { for(b = sbl->l.First(); b; b = sbl->l.NextAfter(b)) { for(int i = 0; i <= b->deg; i++) { (b->ctrl[i]).MakeMaxMin(&ptMax, &ptMin); } } } } } // And now we compute the canvas size. double s = 1.0 / SS.exportScale; if(SS.exportCanvasSizeAuto) { // It's based on the calculated bounding box; we grow it along each // boundary by the specified amount. ptMin.x -= s*SS.exportMargin.left; ptMax.x += s*SS.exportMargin.right; ptMin.y -= s*SS.exportMargin.bottom; ptMax.y += s*SS.exportMargin.top; } else { ptMin.x = -(s*SS.exportCanvas.dx); ptMin.y = -(s*SS.exportCanvas.dy); ptMax.x = ptMin.x + (s*SS.exportCanvas.width); ptMax.y = ptMin.y + (s*SS.exportCanvas.height); } // If the demo period has expired and there's no license, then print // a message in any exported file. if((!SS.license.licensed) && (SS.license.trialDaysRemaining <= 0) && sblss){ char *str = "eval / nonprofit use only -- buy at http://solvespace.com/"; double aspect = (glxStrWidth(str, 1) / glxStrHeight(1)); double w = ptMax.x - ptMin.x, h = ptMax.y - ptMin.y; Vector u, v, t; double th; if(w > h) { th = w / aspect; u = Vector::From(1, 0, 0); v = Vector::From(0, 1, 0); t = Vector::From(ptMin.x + (w/2), ptMin.y - 1.5*th, 0); } else { th = h / aspect; u = Vector::From( 0, 1, 0); v = Vector::From(-1, 0, 0); t = Vector::From(ptMax.x + 1.5*th, ptMin.y + (h/2) , 0); } glxWriteTextRefCenter( str, 0.9 * th * SS.GW.scale, t, u, v, AddUnregMessageCallback, sblss); if(w > h) { ptMin.y -= th*3; } else { ptMax.x += th*3; } } StartFile(); if(sm && SS.exportShadedTriangles) { for(tr = sm->l.First(); tr; tr = sm->l.NextAfter(tr)) { Triangle(tr); } } if(sblss) { SBezierLoopSet *sbls; for(sbls = sblss->l.First(); sbls; sbls = sblss->l.NextAfter(sbls)) { SBezierLoop *sbl; sbl = sbls->l.First(); if(!sbl) continue; b = sbl->l.First(); if(!b || !Style::Exportable(b->auxA)) continue; hStyle hs = { b->auxA }; Style *stl = Style::Get(hs); double lineWidth = Style::WidthMm(b->auxA)*s; DWORD strokeRgb = Style::Color(b->auxA, true); StartPath(strokeRgb, lineWidth, stl->filled, stl->fillColor); for(sbl = sbls->l.First(); sbl; sbl = sbls->l.NextAfter(sbl)) { for(b = sbl->l.First(); b; b = sbl->l.NextAfter(b)) { Bezier(b); } } FinishPath(strokeRgb, lineWidth, stl->filled, stl->fillColor); } } FinishAndCloseFile(); } void VectorFileWriter::BezierAsPwl(SBezier *sb) { List lv; ZERO(&lv); sb->MakePwlInto(&lv, SS.ChordTolMm() / SS.exportScale); int i; for(i = 1; i < lv.n; i++) { SBezier sb = SBezier::From(lv.elem[i-1], lv.elem[i]); Bezier(&sb); } lv.Clear(); } void VectorFileWriter::BezierAsNonrationalCubic(SBezier *sb, int depth) { Vector t0 = sb->TangentAt(0), t1 = sb->TangentAt(1); // The curve is correct, and the first derivatives are correct, at the // endpoints. SBezier bnr = SBezier::From( sb->Start(), sb->Start().Plus(t0.ScaledBy(1.0/3)), sb->Finish().Minus(t1.ScaledBy(1.0/3)), sb->Finish()); double tol = SS.ChordTolMm() / SS.exportScale; // Arbitrary choice, but make it a little finer than pwl tolerance since // it should be easier to achieve that with the smooth curves. tol /= 2; bool closeEnough = true; int i; for(i = 1; i <= 3; i++) { double t = i/4.0; Vector p0 = sb->PointAt(t), pn = bnr.PointAt(t); double d = (p0.Minus(pn)).Magnitude(); if(d > tol) { closeEnough = false; } } if(closeEnough || depth > 3) { Bezier(&bnr); } else { SBezier bef, aft; sb->SplitAt(0.5, &bef, &aft); BezierAsNonrationalCubic(&bef, depth+1); BezierAsNonrationalCubic(&aft, depth+1); } } //----------------------------------------------------------------------------- // Export a triangle mesh, in the requested format. //----------------------------------------------------------------------------- void SolveSpace::ExportMeshTo(char *filename) { SMesh *m = &(SK.GetGroup(SS.GW.activeGroup)->displayMesh); if(m->IsEmpty()) { Error("Active group mesh is empty; nothing to export."); return; } FILE *f = fopen(filename, "wb"); if(!f) { Error("Couldn't write to '%s'", filename); return; } if(StringEndsIn(filename, ".stl")) { ExportMeshAsStlTo(f, m); } else if(StringEndsIn(filename, ".obj")) { ExportMeshAsObjTo(f, m); } else { Error("Can't identify output file type from file extension of " "filename '%s'; try .stl, .obj.", filename); } fclose(f); } //----------------------------------------------------------------------------- // Export the mesh as an STL file; it should always be vertex-to-vertex and // not self-intersecting, so not much to do. //----------------------------------------------------------------------------- void SolveSpace::ExportMeshAsStlTo(FILE *f, SMesh *sm) { char str[80]; memset(str, 0, sizeof(str)); strcpy(str, "STL exported mesh"); fwrite(str, 1, 80, f); DWORD n = sm->l.n; fwrite(&n, 4, 1, f); double s = SS.exportScale; int i; for(i = 0; i < sm->l.n; i++) { STriangle *tr = &(sm->l.elem[i]); Vector n = tr->Normal().WithMagnitude(1); float w; w = (float)n.x; fwrite(&w, 4, 1, f); w = (float)n.y; fwrite(&w, 4, 1, f); w = (float)n.z; fwrite(&w, 4, 1, f); w = (float)((tr->a.x)/s); fwrite(&w, 4, 1, f); w = (float)((tr->a.y)/s); fwrite(&w, 4, 1, f); w = (float)((tr->a.z)/s); fwrite(&w, 4, 1, f); w = (float)((tr->b.x)/s); fwrite(&w, 4, 1, f); w = (float)((tr->b.y)/s); fwrite(&w, 4, 1, f); w = (float)((tr->b.z)/s); fwrite(&w, 4, 1, f); w = (float)((tr->c.x)/s); fwrite(&w, 4, 1, f); w = (float)((tr->c.y)/s); fwrite(&w, 4, 1, f); w = (float)((tr->c.z)/s); fwrite(&w, 4, 1, f); fputc(0, f); fputc(0, f); } } //----------------------------------------------------------------------------- // Export the mesh as Wavefront OBJ format. This requires us to reduce all the // identical vertices to the same identifier, so do that first. //----------------------------------------------------------------------------- void SolveSpace::ExportMeshAsObjTo(FILE *f, SMesh *sm) { SPointList spl; ZERO(&spl); STriangle *tr; for(tr = sm->l.First(); tr; tr = sm->l.NextAfter(tr)) { spl.IncrementTagFor(tr->a); spl.IncrementTagFor(tr->b); spl.IncrementTagFor(tr->c); } // Output all the vertices. SPoint *sp; for(sp = spl.l.First(); sp; sp = spl.l.NextAfter(sp)) { fprintf(f, "v %.10f %.10f %.10f\r\n", sp->p.x / SS.exportScale, sp->p.y / SS.exportScale, sp->p.z / SS.exportScale); } // And now all the triangular faces, in terms of those vertices. The // file format counts from 1, not 0. for(tr = sm->l.First(); tr; tr = sm->l.NextAfter(tr)) { fprintf(f, "f %d %d %d\r\n", spl.IndexForPoint(tr->a) + 1, spl.IndexForPoint(tr->b) + 1, spl.IndexForPoint(tr->c) + 1); } spl.Clear(); } //----------------------------------------------------------------------------- // Export a view of the model as an image; we just take a screenshot, by // rendering the view in the usual way and then copying the pixels. //----------------------------------------------------------------------------- void SolveSpace::ExportAsPngTo(char *filename) { int w = (int)SS.GW.width, h = (int)SS.GW.height; // No guarantee that the back buffer contains anything valid right now, // so repaint the scene. And hide the toolbar too. int prevShowToolbar = SS.showToolbar; SS.showToolbar = false; SS.GW.Paint(); SS.showToolbar = prevShowToolbar; FILE *f = fopen(filename, "wb"); if(!f) goto err; png_struct *png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); if(!png_ptr) goto err; png_info *info_ptr = png_create_info_struct(png_ptr); if(!png_ptr) goto err; if(setjmp(png_jmpbuf(png_ptr))) goto err; png_init_io(png_ptr, f); // glReadPixels wants to align things on 4-boundaries, and there's 3 // bytes per pixel. As long as the row width is divisible by 4, all // works out. w &= ~3; h &= ~3; png_set_IHDR(png_ptr, info_ptr, w, h, 8, PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,PNG_FILTER_TYPE_DEFAULT); png_write_info(png_ptr, info_ptr); // Get the pixel data from the framebuffer BYTE *pixels = (BYTE *)AllocTemporary(3*w*h); BYTE **rowptrs = (BYTE **)AllocTemporary(h*sizeof(BYTE *)); glReadPixels(0, 0, w, h, GL_RGB, GL_UNSIGNED_BYTE, pixels); int y; for(y = 0; y < h; y++) { // gl puts the origin at lower left, but png puts it top left rowptrs[y] = pixels + ((h - 1) - y)*(3*w); } png_write_image(png_ptr, rowptrs); png_write_end(png_ptr, info_ptr); png_destroy_write_struct(&png_ptr, &info_ptr); fclose(f); return; err: Error("Error writing PNG file '%s'", filename); if(f) fclose(f); return; }