topic Re: Easy gdl mesh in GDL

Easy gdl mesh

rudl — Tue, 14 Oct 2025 08:03:23 GMT

Easy mesh:

! No more VERT EDGE PGON ! (because its a bit of a pain)

just a vertex array

and a face array with vert indices

Face direction should be automatic with the order of vertices, Edges are automatic

Needs more testing, may add some more features.

! ------------------------------------------------------------ ! Geometry stored in vert and pgon arrays only Example: Pyramid ! ------------------------------------------------------------ ! Important order of vertices in Pgon determine Normal / Face direction ! --- SETUP VARIABLES --- dim points_s[][3] !points start dim edges_pi[][2] !edges point index dim faces_pi[][] !faces point index dim ppf[] !points per face ! --- POPULATE --- points_s[1][1] = -1 : points_s[1][2] = -1 : points_s[1][3] = 0 ! base points_s[2][1] = 1 : points_s[2][2] = -1 : points_s[2][3] = 0 points_s[3][1] = 1 : points_s[3][2] = 1 : points_s[3][3] = 0 points_s[4][1] = -1 : points_s[4][2] = 1 : points_s[4][3] = 0 points_s[5][1] = 0 : points_s[5][2] = 0 : points_s[5][3] = 2 ! apex ppf[1] = 4 : faces_pi[1][1] = 1 : faces_pi[1][2] = 4 : faces_pi[1][3] = 3 : faces_pi[1][4] = 2 ! base (quad) ppf[2] = 3 : faces_pi[2][1] = 1 : faces_pi[2][2] = 2 : faces_pi[2][3] = 5 ppf[3] = 3 : faces_pi[3][1] = 2 : faces_pi[3][2] = 3 : faces_pi[3][3] = 5 ppf[4] = 3 : faces_pi[4][1] = 3 : faces_pi[4][2] = 4 : faces_pi[4][3] = 5 ppf[5] = 3 : faces_pi[5][1] = 4 : faces_pi[5][2] = 1 : faces_pi[5][3] = 5 nPoints = 5 ! this should be known does not make sense to calc! optional with VARDIM1 nFaces = 5 ! this should be known does not make sense to calc! optional with VARDIM1 ! ------------------------------------------------------------ ! DO THE MAGIC THING: ! ------------------------------------------------------------ ! --- Point index for edges --- edges_pi[][2] for use in EDGE x=0 ! the counter is important! FOR i=1 TO nFaces FOR j=1 TO ppf[i] x = x+1 IF j < ppf[i] THEN edges_pi[x][1]=faces_pi[i][j] edges_pi[x][2]=faces_pi[i][j+1] ELSE edges_pi[x][1]=faces_pi[i][j] !connect last point of face with first edges_pi[x][2]=faces_pi[i][1] ENDIF NEXT j NEXT i lengthedge = VARDIM1 (edges_pi) ! total edges with duplicates should be nEDGE ! --- Create edge index --- edges[] for use in PGON ! There is some kind of "sorting" through to make the double edge indices negative ! could be optimised for larger meshes though DIM edges[] negcount = 0 FOR i = 1 TO lengthedge u = edges_pi[i][1] v = edges_pi[i][2] edges[i]=i-negcount FOR j = 1 To i IF edges_pi[j][1]=v AND edges_pi[j][2] = u THEN edges[i]= edges[j]*(-1) negcount = negcount+1 ENDIF NEXT J NEXT i ! ------------------------------------------------------------ ! BUILDING THE MESH: ! ------------------------------------------------------------ !PUT EVERYTHING TOGETHER BASE FOR i = 1 TO nPoints VERT points_s[i][1],points_s[i][2],points_s[i][3] NEXT i FOR i = 1 TO lengthedge IF edges[i]>=1 THEN EDGE edges_pi[i][1], edges_pi[i][2],-1,-1,0 ENDIF NEXT i PUT edges FOR i = 1 TO nFaces PGON ppf[i],0,0,GET(ppf[i]) NEXT i BODY -1 ! ------------------------------------------------------------ ! DEBUG: ! ------------------------------------------------------------ !PRINT edges_pi !PRINT edges

Re: Easy gdl mesh

Barry Kelly — Tue, 14 Oct 2025 08:17:15 GMT

Thanks for showing the method, but I am not sure I understand the purpose.

You did use VERT EDGE PGON, just in a loop.

And wouldn't it be easier to use the PYRAMID command?

Barry.

Re: Easy gdl mesh

rudl — Tue, 14 Oct 2025 08:29:07 GMT

In the end of course i used Vert edge and pgons etc.

The pyramid is just a simple example I'm thinking about much more complex things. Its more about how it is stored

Its way easier if you have indices than the order of creation

especially if you want to create something parametric where the number of vertices edges pgons is not known

Re: Easy gdl mesh

rudl — Tue, 14 Oct 2025 20:57:12 GMT

Not a pyramid:
In conjunction with a blender script (I did us chatgpt for that)

import bpy # Output file path output_file = "C:/Users/potato/mesh_data.txt" # <-- change this with open(output_file, 'w') as f: vertex_count = 1 face_count = 1 for obj in bpy.context.selected_objects: # or bpy.data.objects for all if obj.type != 'MESH': continue mesh = obj.data #f.write(f"// Object: {obj.name}\n\n") # Write vertices for v in mesh.vertices: f.write(f"points_s[{vertex_count}][1] = {v.co.x}\n") f.write(f"points_s[{vertex_count}][2] = {v.co.y}\n") f.write(f"points_s[{vertex_count}][3] = {v.co.z}\n") vertex_count += 1 f.write("\n") # Write faces for p in mesh.polygons: # Ensure we only handle triangles or quads (can expand if needed) verts = p.vertices for i in range(len(verts)): f.write(f"faces_pi[{face_count}][{i+1}] = {verts[i]+1}\n") # +1 for 1-based indexing face_count += 1 f.write("\n") print(f"Mesh data exported to {output_file}")

Re: Easy gdl mesh

rudl — Sat, 25 Oct 2025 21:51:37 GMT

Was a little slow but it should be much faster now.
Sorted the edges before checking for the "oposite edge" otherwise it loops through the whole array for every edge. ^^

! --- SETUP VARIABLES --- dim po_s[][3] !points start dim edges_pi[][2] !edges point index dim f_pi[][] !faces point index dim ppf[] !points per face ! --- POPULATE --- po_s[1][1] = 0.03838 : po_s[1][2] = -0.02232 : po_s[1][3] = 0.08784 po_s[2][1] = -0.01273 : po_s[2][2] = 0.01263 : po_s[2][3] = 0.14178 po_s[3][1] = -0.07195 : po_s[3][2] = -0.01823 : po_s[3][3] = 0.08623 po_s[4][1] = 0.0298 : po_s[4][2] = -0.00251 : po_s[4][3] = 0.09868 ... po_s[243][1] = 0.0156 : po_s[243][2] = -0.03653 : po_s[243][3] = -0.0 po_s[244][1] = -0.04308 : po_s[244][2] = 0.03277 : po_s[244][3] = 0.1129 po_s[245][1] = -0.04553 : po_s[245][2] = 0.0671 : po_s[245][3] = 0.1219 f_pi[1][1]=5:f_pi[1][2]=141:f_pi[1][3]=28 : f_pi[2][1]=122:f_pi[2][2]=133:f_pi[2][3]=148 : f_pi[3][1]=147:f_pi[3][2]=11:f_pi[3][3]=111 f_pi[4][1]=134:f_pi[4][2]=52:f_pi[4][3]=124 : f_pi[5][1]=5:f_pi[5][2]=12:f_pi[5][3]=141 : f_pi[6][1]=28:f_pi[6][2]=141:f_pi[6][3]=31 f_pi[7][1]=21:f_pi[7][2]=155:f_pi[7][3]=163 : f_pi[8][1]=194:f_pi[8][2]=134:f_pi[8][3]=124 : f_pi[9][1]=52:f_pi[9][2]=134:f_pi[9][3]=40 ... f_pi[478][1]=230:f_pi[478][2]=229:f_pi[478][3]=238 : f_pi[479][1]=229:f_pi[479][2]=227:f_pi[479][3]=222 : f_pi[480][1]=222:f_pi[480][2]=224:f_pi[480][3]=229 f_pi[481][1]=223:f_pi[481][2]=226:f_pi[481][3]=225 : f_pi[482][1]=226:f_pi[482][2]=233:f_pi[482][3]=225 : f_pi[483][1]=243:f_pi[483][2]=238:f_pi[483][3]=240 f_pi[484][1]=240:f_pi[484][2]=232:f_pi[484][3]=243 : f_pi[485][1]=233:f_pi[485][2]=243:f_pi[485][3]=235 : f_pi[486][1]=232:f_pi[486][2]=235:f_pi[486][3]=243 nPoints = 245 ! this should be known does not make sense to calc! optional with VARDIM1 nFaces = 486 ! this should be known does not make sense to calc! optional with VARDIM1 FOR i=1 TO nFaces ppf[i]=3 NEXT i ! ------------------------------------------------------------ ! DO THE MAGIC THING: ! ------------------------------------------------------------ ! --- Point index for edges --- edges_pi[][2] for use in EDGE DIM edges_so[][] x=0 ! the counter is important! FOR i=1 TO nFaces FOR j=1 TO ppf[i] x = x+1 IF j < ppf[i] THEN edges_pi[x][1]=f_pi[i][j] edges_pi[x][2]=f_pi[i][j+1] ELSE edges_pi[x][1]=f_pi[i][j] !connect last point of face with first edges_pi[x][2]=f_pi[i][1] ENDIF edges_so[edges_pi[x][1]][1] = edges_so[edges_pi[x][1]][1]+1 !self+1 edges_so[edges_pi[x][1]][edges_so[edges_pi[x][1]][1]+1] = x NEXT j NEXT i nEdges = VARDIM1 (edges_pi) ! total edges with duplicates negcount = 0 DIM edges[] FOR i = 1 TO nEdges !edges_pi[i][2] IF edges[i] < 0 THEN negcount = negcount +1 ELSE tempi = i-negcount FOR j = 2 TO edges_so[edges_pi[i][2]][1]+1 IF edges_pi[i][1] = edges_pi[edges_so[edges_pi[i][2]][j]][2] THEN !"PRINT "gefunden" edges[i] = tempi edges[edges_so[edges_pi[i][2]][j]] = -tempi ENDIF NEXT j ENDIF NEXT i ! ------------------------------------------------------------ ! BUILDING THE MESH: ! ------------------------------------------------------------ BASE FOR i = 1 TO nPoints VERT po_s[i][1],po_s[i][2],po_s[i][3] NEXT i FOR i = 1 TO nEdges IF edges[i]>=1 THEN EDGE edges_pi[i][1], edges_pi[i][2],-1,-1,0 ENDIF NEXT i PUT edges FOR i = 1 TO nFaces PGON ppf[i],0,0,GET(ppf[i]) NEXT i BODY -1

Full res bunny example:
69664 Faces, 34834 Points

Re: Easy gdl mesh

rudl — Mon, 03 Nov 2025 23:21:37 GMT

"Hair"

Face - Normals added

Re: Easy gdl mesh

Barry Kelly — Tue, 04 Nov 2025 00:50:37 GMT

This is all very impressive, I like it.

But where are you getting the x,y,z co-ordinates for the model.

Doesn't it mean that someone has modelled it up already?

I do quite a few basins and baths based on converted RVT, OBJ, SKP, 3DS, etc, objects.

I would love to reduce there 50000+ lines of code down to something much simpler like this.

Barry.

Re: Easy gdl mesh

rudl — Sat, 08 Nov 2025 21:51:30 GMT

*) Edge Angles
*) Edge Visibility/sharp edges based on edge angle.

Re: Easy gdl mesh

rudl — Fri, 14 Nov 2025 23:19:22 GMT

Face and Vertex numbering, Point normals etc

Re: Easy gdl mesh

Davor P — Sun, 16 Nov 2025 07:57:02 GMT

Might be useful if you are storing points and faces in a text file and read them with gdl.

Re: Easy gdl mesh

rudl — Tue, 18 Nov 2025 23:52:34 GMT

That is definitely on my todo list.
Main focus is still making it easier to script meshes within gdl.

Re: Easy gdl mesh

rudl — Wed, 19 Nov 2025 00:01:25 GMT

Parametric torus and bended beams.

Torus example:

theta = 360/u FOR i = 2 TO u vec_temp[1]=po_s[i-1] GOSUB "V_ArotX": po_s[i] = vec_temp[3] NEXT i FOR i =1 TO u po_s[i][2]= po_s[i][2]+rv NEXT i theta = 360/v FOR i = 1 TO v-1 FOR j = 1 TO u vec_temp[1]=po_s[(i-1)*u+j] GOSUB "V_ArotZ": po_s[i*u+j] = vec_temp[3] NEXT j NEXT i c =0 FOR i = 1 TO v FOR j = 1 TO u IF i = v THEN IF j = u THEN c = c +1 f_pi[c][1]=(i-1)*u+j f_pi[c][2]= j f_pi[c][3]=(i-2)*u+j+1 c = c +1 f_pi[c][1]= j f_pi[c][2]= 1 f_pi[c][3]=(i-2)*u+j+1 ELSE c = c +1 f_pi[c][1]=(i-1)*u+j f_pi[c][2]= j f_pi[c][3]=(i-1)*u+j+1 c = c +1 f_pi[c][1]= j f_pi[c][2]= j+1 f_pi[c][3]= (i-1)*u+j+1 ENDIF ELSE IF j = u THEN c = c +1 f_pi[c][1]=(i-1)*u+j f_pi[c][2]=(i)*u+j f_pi[c][3]=(i-2)*u+j+1 c = c +1 f_pi[c][1]=(i)*u+j f_pi[c][2]=(i-1)*u+j+1 f_pi[c][3]=(i-2)*u+j+1 ELSE c = c +1 f_pi[c][1]=(i-1)*u+j f_pi[c][2]=(i)*u+j f_pi[c][3]=(i-1)*u+j+1 c = c +1 f_pi[c][1]= (i)*u+j f_pi[c][2]= (i)*u+j+1 f_pi[c][3]= (i-1)*u+j+1 ENDIF ENDIF NEXT j NEXT i

Re: Easy gdl mesh

rudl — Tue, 09 Dec 2025 23:30:50 GMT

*) Monkey read from text-file
*) Arbitary rotation around an axis rodriques transformation
*) Display Helper Axes