Naive surface nets for GameMaker2

For more detail about surface nets, please refer to articles about this subject.
This is meant for 3D project, assume you already worked out how to render 3D models.
As provided, these function will generate model buffer with standard format:

vertex_format_begin();
vertex_format_add_position_3d();
vertex_format_add_normal();
vertex_format_add_texcoord();
vertex_format_add_colour();
global.stdFormat = vertex_format_end();

Some commands is also required for this function to work, such as normalize, cross_product,... You can check them inside Requisitive_function script (they might already included in your project).

How to use

Import the script directly into your project.
auto_mesh functions are included as simple example on how to use this function. You should create your own function to fit your use case.

• First, use auto_mesh_create() to create a list to contain shapes information.
• Then, use auto_mesh_add_ to add shapes into this list.
• Finally supply the shape list and a buffer into the function naive_surface_nets to generate mesh.

buffer = buffer_create(64, buffer_grow, 1)
mesh = auto_mesh_create();
auto_mesh_add_AABB(mesh,10,100,10,300,200,200)
auto_mesh_add_sphere(mesh, 150, 150, 300, 130)
naive_surface_nets(mesh, buffer, 32, 0.5, 3);

Create vertex buffer and render

vertex_buff = vertex_create_buffer_from_buffer(buffer, global.stdFormat)
vertex_submit(vertex_buff, pr_trianglelist, -1);

Draw back

• This script use iso gradient to estimate surface direction, which can be inaccurate near sharp corners.
• The process can be very slow and intense on CPU, real time generation is not possible.
• If the shape is too small it can create extra, unnecessary vertexs inside the shape, invisible from outside.
• Due to the nature of this method, the final mesh will become 'shrinked', user should take this into account.
• I'm suck at coding.

Screenshot

Box shape

auto_mesh_add_AABB(mesh_test,10,100,10,300,300,300)

Sphere shape

auto_mesh_add_sphere(mesh_test, 300, 150, 150, 120)

Perlin noise

auto_mesh_add_noise(mesh_test,0,0,0,2048,2048,600);

with naive_surface_nets_smooth_normal function