GLSL Hacker has a handy object called a grid. A grid is more or less just a collection of lines but that info is not really important. You can use a grid as a reference object when there’s no ground plane in the scene.
To use a grid, you need a grid (obviously), a vertex color GPU program and a camera (a perspective in our code snippet).
The following code shows the initialization of a 100×100 units grid made up of 20×20 segments:
grid = gh_utils.grid_create() gh_utils.grid_set_geometry_params(grid, 100, 100, 20, 20) gh_utils.grid_set_lines_color(grid, 0.7, 0.7, 0.7, 1.0) gh_utils.grid_set_main_lines_color(grid, 1.0, 1.0, 0.0, 1.0) gh_utils.grid_set_main_x_axis_color(grid, 1.0, 0.0, 0.0, 1.0) gh_utils.grid_set_main_z_axis_color(grid, 0.0, 0.0, 1.0, 1.0) local display_main_lines = 1 local display_lines = 1 gh_utils.grid_set_display_lines_options(grid, display_main_lines, display_lines)
For the vertex color GLSL program, you can use this one (OpenGL 2 style):
Or this one, in OpenGL 3 style:
We can retrieve the gpu program handle with this code:
color_prog = gh_node.getid("color_prog")
The perspective camera:
winW, winH = gh_window.getsize(0) local aspect = winW / winH camera = gh_camera.create_persp(60, aspect, 1.0, 1000.0) gh_camera.set_viewport(camera, 0, 0, winW, winH) gh_camera.set_position(camera, 20, 20, 80) gh_camera.set_lookat(camera, 0, 0, 0, 1) gh_camera.setupvec(camera, 0, 1, 0, 0)
Now we can render the reference grid:
gh_camera.bind(camera) gh_renderer.clear_color_depth_buffers(0.2, 0.2, 0.2, 1.0, 1.0) gh_gpu_program.bind(color_prog) gh_object.render(grid)