#####[ Tips for importing OBJ (Wavefront) 3D models ]#####

Last updated: 2023/11/25

Game Maker 6-8
--------------
If importing using actual Game Maker, you will need some scripts as
otherwise, you will need to find a Blender plugin to help you export the
model as D3D. Use the following script to help GM6 and newer load OBJ 3D
models. The script starts and stops between the dotted lines; do not 
copy/paste the dotted lines. Make sure to keep reading afterwards.

------------------------[scr_createFromOBJ]-----------------------------

// MOSAIC Light 3D OBJ IMPORTER
// (c) 2006. Zoltan Percsich. All Rights Reserved.
// Don't edit this script

filename=argument0;
flipnormals = 1;
if (argument1>0) flipnormals=-1;
vertex_list1=ds_list_create();ds_list_clear(vertex_list1);ds_list_add(vertex_list1,0);
vertex_list2=ds_list_create();ds_list_clear(vertex_list2);ds_list_add(vertex_list2,0);
vertex_list3=ds_list_create();ds_list_clear(vertex_list3);ds_list_add(vertex_list3,0);
normal_list1=ds_list_create();ds_list_clear(normal_list1);ds_list_add(normal_list1,0);
normal_list2=ds_list_create();ds_list_clear(normal_list2);ds_list_add(normal_list2,0);
normal_list3=ds_list_create();ds_list_clear(normal_list3);ds_list_add(normal_list3,0);
texture_list1=ds_list_create();ds_list_clear(texture_list1);ds_list_add(texture_list1,0);
texture_list2=ds_list_create();ds_list_clear(texture_list2);ds_list_add(texture_list2,0);
faces_list=ds_list_create();ds_list_clear(faces_list);
fp=file_text_open_read(filename);

for (i=0;file_text_eof(fp)==false;i+=1) {

    row=file_text_read_string(fp);row=string_replace_all(row,"  "," ");
    
    if (string_char_at(row,1)=="v" && string_char_at(row,2)==" ") {
        row=string_delete(row,1,string_pos(" ",row));
        vx=real(string_copy(row,1,string_pos(" ",row)));
        row=string_delete(row,1,string_pos(" ",row));
        vy=real(string_copy(row,1,string_pos(" ",row)));
        row=string_delete(row,1,string_pos(" ",row));
        vz=real(string_copy(row,1,string_length(row)));
        ds_list_add(vertex_list1,vx);
        ds_list_add(vertex_list2,vy);
        ds_list_add(vertex_list3,vz);
    }
    
    if (string_char_at(row,1)=="v" && string_char_at(row,2)=="n") {
        row=string_delete(row,1,string_pos(" ",row));
        nx=real(string_copy(row,1,string_pos(" ",row)));
        row=string_delete(row,1,string_pos(" ",row));
        ny=real(string_copy(row,1,string_pos(" ",row)));
        row=string_delete(row,1,string_pos(" ",row));
        nz=real(string_copy(row,1,string_length(row)));
        ds_list_add(normal_list1,nx);
        ds_list_add(normal_list2,ny);
        ds_list_add(normal_list3,nz);
    }
    
    if (string_char_at(row,1)=="v" && string_char_at(row,2)=="t") {
        row=string_delete(row,1,string_pos(" ",row));
        tx=real(string_copy(row,1,string_pos(" ",row)));
        row=string_delete(row,1,string_pos(" ",row));
        ty=real(string_copy(row,1,string_length(row)));
        ds_list_add(texture_list1,tx);
        ds_list_add(texture_list2,ty);
    }
    
    if (string_char_at(row,1)=="f" && string_char_at(row,2)==" ") {
        row=string_replace_all(row,"  "," ");
        row=string_delete(row,1,string_pos(" ",row));
        if (string_char_at(row,string_length(row))==" ") row=string_copy(row,0,string_length(row)-1);
        face_num=string_count(" ",row);
        face_division=1;
        temp_faces[0]=0;
        
        for (fc=0;fc<face_num;fc+=1) {
            f=string_copy(row,1,string_pos(" ",row));
            row=string_delete(row,1,string_pos(" ",row));
            temp_faces[face_division]=f;
            face_division+=1;
        }
            
        f=string_copy(row,1,string_length(row));temp_faces[face_division]=f;
        if (face_division==3) {
            f1=temp_faces[2];
            f2=temp_faces[3];
            f3=temp_faces[1];
            ds_list_add(faces_list,f1);
            ds_list_add(faces_list,f2);
            ds_list_add(faces_list,f3);
        } else {
            f1=temp_faces[2];
            f2=temp_faces[3];
            f3=temp_faces[1];
            ds_list_add(faces_list,f1);
            ds_list_add(faces_list,f2);
            ds_list_add(faces_list,f3);
            for (t=0;t<face_division-3;t+=1) {
                f1=temp_faces[4+t];
                f2=temp_faces[1];
                f3=temp_faces[3+t];
                ds_list_add(faces_list,f1);
                ds_list_add(faces_list,f2);
                ds_list_add(faces_list,f3);
            }
        }
    } 
    
    file_text_readln(fp);          
}
file_text_close(fp);

tm=d3d_model_create();
tsn=0;
d3d_model_primitive_begin(tm,pr_trianglelist);       

for (fc=0;fc<ds_list_size(faces_list);fc+=1) {

    sub_face=ds_list_find_value(faces_list,fc);
    
    if (string_count("/",sub_face)==0) {
        f_index=sub_face;
        t_index=-1;
        n_index=-1;
    }
    
    if (string_count("/",sub_face)==1) {
        f_index=string_copy(sub_face,1,string_pos("/",sub_face)-1);
        sub_face=string_delete(sub_face,1,string_pos("/",sub_face));
        t_index=string_copy(sub_face,1,string_length(sub_face));
        n_index=-1;
    }
    
    if (string_count("/",sub_face)==2 && string_count("//",sub_face)==0) {
        f_index=string_copy(sub_face,1,string_pos("/",sub_face)-1);
        sub_face= string_delete(sub_face,1,string_pos("/",sub_face));
        t_index=string_copy(sub_face,1,string_pos("/",sub_face)-1);
        sub_face= string_delete(sub_face,1,string_pos("/",sub_face));
        n_index=string_copy(sub_face,1,string_length(sub_face));
    }
    
    if (string_count("/",sub_face)==2 && string_count("//",sub_face)==1) {
        sub_face=string_replace(sub_face,"//","/");
        f_index=string_copy(sub_face,1,string_pos("/",sub_face)-1);
        sub_face= string_delete(sub_face,1,string_pos("/",sub_face));
        t_index=-1;
        n_index=string_copy(sub_face,1,string_length(sub_face));
    }
    
    vx=ds_list_find_value(vertex_list1,floor(real(f_index)));
    vy=ds_list_find_value(vertex_list2,floor(real(f_index)));
    vz=ds_list_find_value(vertex_list3,floor(real(f_index)));
    
    if (floor(real(n_index))!=-1 && ds_list_size(normal_list1)>=1) {
        nx=flipnormals*ds_list_find_value(normal_list1,floor(real(n_index)));
        ny=flipnormals*ds_list_find_value(normal_list2,floor(real(n_index)));
        nz=flipnormals*ds_list_find_value(normal_list3,floor(real(n_index)));
    } else {
        nx=0;
        ny=0;
        nz=0;
    }
    
    if (floor(real(t_index))!=-1 && ds_list_size(texture_list1)>=1) {
        tx=ds_list_find_value(texture_list1,floor(real(t_index)));
        ty=ds_list_find_value(texture_list2,floor(real(t_index)));
    } else {
        tx=0;
        ty=0;
    }
    
    d3d_model_vertex_normal_texture(tm,vx,vy,vz,nx,ny,nz,tx,ty);
    
    tsn+=1;
    if (tsn==999) {
        tsn=0;
        d3d_model_primitive_end(tm);
        d3d_model_primitive_begin(tm,pr_trianglelist);
    }       
}

d3d_model_primitive_end(tm);
return tm;

------------------------------------------------------------------------

Next, you can load a 3D model by placing the following in a script
within the Create Event of the object that is to load the OBJ model....

    //Load the 3D model
    example_model = createFromObj('Example.obj',false)

...You would then use the 
"d3d_model_draw(example_model,0,0,0,spr_example_texture)" like usual or
however you plan on showing the 3D model. What the "MOSAIC Light 3D OBJ 
IMPORTER" script is basically doing is converting an OBJ to a D3D 
format. The true/false part of the argument is to tell the script 
whether or not to flip the normals.

I would also like to point-out that in Blender, if you created a cube
that was 16x16x16 dimensions in size using the standard Blender units,
that cube fits perfectly in relation to Game Maker's room editor grid.
In other words, a 16x16x16 cube made in Blender will fit within a 
640x480 room with d3d enabled 40 times by 30 times, not including 
stacking. Think of a single Blender unit as a single pixel in 
Game Maker.

It is also worth noting that when it comes to importing an OBJ model,
the origin of that model known to Blender does not determine relative 
positioning as far as Game Maker is concerned; in other words, always 
keep the 3D model relative to the center of the scene in Blender and 
the lowest point (such as feet or the bottom of a box) just barely above
the floor level in Blender.

When exporting your OBJ model in Blender, make sure that:

    - Forward: Y Forward
    - Up: Z Up
    - Scale = 1
    
If your model is to be animated, the script above will not work, but
stationary models will be fine. However, if you are using LateralGM+
Enigma, you can get a model to animate but this has to be done by 
showing a different OBJ model for each frame and by using its built-in
OBJ model support. If you export an OBJ model with animation using 
Blender, it will automatically generate a single OBJ model for each
frame for you, assuming that you have "Animation" checked during the
export process.