How to render multiple objects in DIRT.

[Frank-Dz]

Hi~ Can DIRT support rendering multiple objs at the same time? The demo code only provides the scene containing one object.

pixels = dirt.rasterise_deferred(
        vertices=cube_vertices_clip,
        vertex_attributes=tf.concat([
            tf.ones_like(cube_vertices_object[:, :1]),  # mask
            cube_uvs,  # texture coordinates
            cube_normals_world  # normals
        ], axis=1),
        faces=cube_faces,
        background_attributes=tf.zeros([frame_height, frame_width, 6]),
        shader_fn=shader_fn,
        shader_additional_inputs=[texture, light_direction]
    )

Thanks in advance!

[pmh47]

Yes, because DIRT only renders triangles, it doesn't have any concept of grouping them into "objects". So you need to do all your geometry calculations, transformations, etc. on each object separately, then concatenate everything together before calling rasterise_deferred.

Specifically

• vertices should just be concatenated
• faces should be concatenated, and the vertex indices 'shifted' to point to the correct part of vertices and vertex_attributes, e.g. for two objects, the second half of faces should point to the second half of vertices

If using textures, the simplest method is

• the textures themselves should be concatenated along x-axis
• vertex_attributes should be concatenated, and attributes that correspond to texture coordinates (UVs) should be adjusted according to how the textures were concatenated, e.g. for two objects and textures concatenated along x-axis, the u-coordinates in vertex_attributes should be halved, and for the 2nd object shifted by +0.5 to use the 2nd half of the concatenated texture

[Frank-Dz]

Thanks! Follow your guidance I successfully made it. Thanks again!