mjolnir/world)The World module manages the scene graph, nodes, meshes, materials, cameras, lights, and animations. It provides a hierarchical structure for organizing 3D objects and their relationships.
import "../../mjolnir/world"
import cont "../../mjolnir/containers"
// Spawn a node with a mesh
mesh := world.get_builtin_mesh(&engine.world, .CUBE)
mat := world.get_builtin_material(&engine.world, .RED)
node := world.spawn(
&engine.world,
{0, 0, 0}, // position
world.MeshAttachment{handle = mesh, material = mat, cast_shadow = true},
) or_else {}
// Spawn a child node
child := world.spawn_child(
&engine.world,
node, // parent handle
position = {0, 2, 0},
attachment = world.MeshAttachment{handle = mesh, material = mat},
) or_else {}// Get node pointer
node_ptr := cont.get(engine.world.nodes, node) or_return
// Access node properties
log.infof("Node name: %s", node_ptr.name)
log.infof("Position: %v", node_ptr.transform.position)
// Iterate children
for child_handle in node_ptr.children {
child := cont.get(engine.world.nodes, child_handle) or_continue
log.infof("Child: %s", child.name)
}All transformation functions have _by variants
(relative) and absolute variants:
// Translate (absolute position)
world.translate(&engine.world, node, x = 5, y = 0, z = 0)
// Translate by offset (relative)
world.translate_by(&engine.world, node, x = 1, y = 0, z = 0)
// Rotate (absolute rotation)
world.rotate(&engine.world, node, math.PI * 0.5, {0, 1, 0})
// Rotate by angle (relative)
world.rotate_by(&engine.world, node, delta_time * math.PI)
// Scale (uniform)
world.scale(&engine.world, node, 2.0)
// Scale (non-uniform)
world.scale_xyz(&engine.world, node, x = 2, y = 1, z = 2)import "../../mjolnir/geometry"
// Create custom geometry
geom := geometry.Geometry{
vertices = vertices,
indices = indices,
aabb = geometry.aabb_from_vertices(vertices),
}
// Upload to GPU and get handle
mesh_handle, gpu_handle, ok := world.create_mesh(&engine.world, geom, keep_cpu_copy = false)
// Create material
material_handle, ok := world.create_material(
&engine.world,
type = .PBR,
metallic_value = 0.5,
roughness_value = 0.8,
emissive_value = 0.1,
)
// Spawn with custom mesh
node := world.spawn(
&engine.world,
{0, 0, 0},
world.MeshAttachment{handle = mesh_handle, material = material_handle},
) or_else {}// Builtin materials
mat := world.get_builtin_material(&engine.world, .RED)
// Available colors: .RED, .GREEN, .BLUE, .YELLOW, .CYAN, .MAGENTA, .WHITE, .GRAY, .BLACK
// Create PBR material
pbr_mat, ok := world.create_material(
&engine.world,
type = .PBR,
base_color_factor = {1.0, 0.5, 0.2, 1.0},
metallic_value = 0.8,
roughness_value = 0.2,
emissive_value = 0.5,
)
// Random color material (useful for debugging)
debug_mat, ok := world.create_material(
&engine.world,
type = .RANDOM_COLOR,
base_color_factor = {1.0, 1.0, 1.0, 1.0},
)
// Line strip material
line_mat, ok := world.create_material(
&engine.world,
type = .LINE_STRIP,
base_color_factor = {1.0, 0.8, 0.0, 1.0},
)// Directional light (sun)
light := world.spawn(
&engine.world,
{0, 10, 0},
world.create_directional_light_attachment(
color = {1.0, 1.0, 1.0, 1.0},
intensity = 10.0,
cast_shadow = true,
),
) or_else {}
// Point light
point_light := world.spawn(
&engine.world,
{5, 3, 5},
world.create_point_light_attachment(
color = {1.0, 0.8, 0.6, 1.0},
intensity = 100.0,
cast_shadow = false,
),
) or_else {}
// Spot light
spot_light := world.spawn(
&engine.world,
{0, 10, 0},
world.create_spot_light_attachment(
color = {0.8, 0.9, 1.0, 1.0},
intensity = 50.0,
outer_cone_angle = math.PI * 0.25,
cast_shadow = true,
),
) or_else {}// Position camera looking at target
world.main_camera_look_at(
&engine.world,
eye_position = {10, 5, 10},
target_position = {0, 0, 0},
)
// Mouse picking - convert screen to world ray
camera := cont.get(engine.world.cameras, engine.world.main_camera)
ray_origin, ray_dir := world.camera_viewport_to_world_ray(
camera,
mouse_x,
mouse_y,
)// Load GLTF with animations
nodes := mjolnir.load_gltf(engine, "assets/CesiumMan.glb")
// Play animation on node
for handle in nodes {
node := cont.get(engine.world.nodes, handle) or_continue
for child in node.children {
if world.play_animation(&engine.world, child, "Walk") {
log.info("Animation started")
}
}
}// Add animation layer (returns true if animation found)
success := world.add_animation_layer(
&engine.world,
node,
animation_name = "Walk",
weight = 1.0,
blend_mode = .REPLACE, // or .ADD
mode = .LOOP,
speed = 1.0,
)
// Adjust layer weight
world.set_animation_layer_weight(&engine.world, node, layer_index = 0, weight = 0.5)
// Blend between two animations
world.set_animation_layer_weight(&engine.world, node, 0, walk_weight)
world.set_animation_layer_weight(&engine.world, node, 1, run_weight)// Add IK layer for a bone chain
bone_chain := []string{"Spine1", "Spine2", "Neck", "Head"}
target_pos := [3]f32{0, 2, 5}
pole_pos := [3]f32{0, 3, 2}
success := world.add_ik_layer(
&engine.world,
node,
bone_chain,
target_pos,
pole_pos,
weight = 1.0,
layer_index = -1, // -1 to append
)
// Update IK target each frame
world.set_ik_layer_target(
&engine.world,
node,
layer_index = 2,
new_target,
new_pole,
)// Tail modifier - creates follow-through motion
success := world.add_tail_modifier_layer(
&engine.world,
node,
root_bone_name = "tail_root",
tail_length = 10,
propagation_speed = 0.85, // How strongly bones react (0-1)
damping = 0.1, // How slowly they return (0-1)
weight = 1.0,
reverse_chain = false,
)
// Single bone rotation - control one bone directly
modifier := world.add_single_bone_rotation_modifier_layer(
&engine.world,
node,
bone_name = "root",
weight = 1.0,
layer_index = -1,
) or_else nil
// Update rotation each frame
if modifier != nil {
modifier.rotation = linalg.quaternion_angle_axis_f32(angle, {0, 1, 0})
}For reading bone world transforms after skinning computation:
// Get computed bone matrices for a skinned node
matrices, skin, node := world.get_bone_matrices(&engine.world, node_handle) or_continue
// Get world-space transform for a specific bone
bone_transform := world.get_bone_world_transform(
&engine.world,
node_handle,
bone_index = u32(5),
) or_continue
// Use bone position/rotation
marker.transform.position = bone_transform.position
marker.transform.rotation = bone_transform.rotation// Despawn a node and all its children
world.despawn(&engine.world, node)
// Destroy a mesh
world.destroy_mesh(&engine.world, mesh_handle)
// Traverse scene graph to update world matrices
world.traverse(&engine.world)// Tag nodes for specific purposes
if node := cont.get(engine.world.nodes, handle); node != nil {
node.tags += {.ENVIRONMENT} // For navmesh baking
node.tags += {.NAVMESH_OBSTACLE} // Mark as obstacle
}