Geometry¶

Meshes represent geometric data in Thunder Engine. The mesh system provides loading, rendering, and optimization of 3D geometry for static and animated objects.

Overview¶

Mesh is the fundamental building block for all visible objects in the scene. The system supports:

Static meshes — for buildings, landscapes, props
Skinned meshes — for characters and animated objects
Procedural meshes — runtime-generated geometry
Optimizations — LOD, batching, instance rendering
File formats — OBJ, FBX, GLTF

Core Components¶

The mesh system consists of several key elements:

Mesh Resource: A resource containing vertex and index data. Loaded from OBJ, FBX, or GLTF files.
MeshRenderer: A component for rendering static meshes. Supports materials, shadows, and culling.
SkinnedMeshRender: A component for rendering skinned meshes with animation.

Mesh Types¶

Static Mesh

Geometry that does not change during gameplay. Optimized for static objects:

Buildings, landscapes, props
Supports static batching
Higher performance

Skinned Mesh

Geometry that deforms under the influence of skeletal animation:

Characters, animals, animated objects
Contains vertex weight data (bone weights)
Updated on GPU for performance

Dynamic Mesh

Geometry generated at runtime:

Terrain, water, procedural objects
Can be updated dynamically
Requires manual buffer management

File Formats¶

Thunder Engine supports the following 3D model formats:

Format	Features
OBJ	Simple text format. Suitable for static geometry. Does not support animation or skeletons.
FBX	Industry standard. Supports animation, skeletons, morphing, cameras, lights. Recommended for complex assets.
GLTF/GLB	Modern format for real-time applications. Efficient loading, PBR support, animations.

When importing assets, all data will be converted to Thunder Engine’s internal formats:

All geometry will be converted to Mesh assets
Animation will be converted to AnimationClip
Material assets will also be created (currently not available)

All assets can be reused independently from each other in your projects.

Import Settings¶

The following settings are available when importing a 3D model:

Use Custom Scale (bool)

Enables the use of custom scale during import.

true — use the value from the Custom Scale field
false — use the original model scale

Default: false.

Custom Scale (float)

Model scale during import. Applied only if Use Custom Scale = true.

Range: from 0.001 to 1000.0
Default: 1.0

Tip

Use for converting units (e.g., from centimeters to meters: 0.01).

Import Color (bool)

Import vertex colors from the model.

true — vertex colors will be loaded and available in shaders
false — vertex colors are ignored

Default: true.

Import Normals (bool)

Import normals from the model.

true — normals are loaded from the file
false — normals are not imported (can be generated later)

Default: true.

Note

Normals are required for proper lighting. If normals are missing from the model, it is recommended to enable their generation.

Import Animation (bool)

Import animation data from the model.

true — animations will be extracted and saved as AnimationClip
false — animations are ignored (static geometry only)

Default: true.

Compress Animation (enum)

Animation data compression method.

Available values:

None — no compression, maximum precision
KeyframeReduction — removes redundant keyframes
CurveOptimization — optimizes curves with specified precision

Default: KeyframeReduction.

Tip

Use compression to reduce animation file size. For background characters, more aggressive compression can be used.

Position Error (float)

Maximum allowable position error during animation compression (in world units).

Smaller value = higher precision, larger file size
Larger value = lower precision, smaller file size

Range: from 0.0001 to 1.0. Default: 0.001.

Rotation Error (float)

Maximum allowable rotation error during animation compression (in degrees).

Smaller value = higher precision, larger file size
Larger value = lower precision, smaller file size

Range: from 0.001 to 10.0. Default: 0.5.

Scale Error (float)

Maximum allowable scale error during animation compression.

Smaller value = higher precision, larger file size
Larger value = lower precision, smaller file size

Range: from 0.0001 to 1.0. Default: 0.001.

Optimization Recommendations¶

For Mobile Platforms

Use meshes with < 10,000 triangles
Limit the number of skeletal bones to 32-64 per character
Enable LOD for all distant objects
Use animation compression with higher error values
Prefer static batching over dynamic

For Desktop Platforms

Meshes up to 100,000 triangles are acceptable
Up to 256 bones per skeleton
Use occlusion culling for complex scenes (not available in current version)
Instance rendering for repeated objects
Lower animation compression error values

General Recommendations

Minimize the number of materials per mesh
Use texture atlases to reduce material switching
Group static geometry
Regularly profile draw call counts
Use LOD for all objects with distance > 50
For animations, use KeyframeReduction compression with moderate error values

Common Issues and Solutions¶

Mesh Does Not Render

Verify that the mesh is loaded (mesh != nullptr)
Check that a material is assigned
Ensure the camera is looking at the object
Check the camera’s near/far planes

Low Performance with Many Meshes

Enable static batching for static geometry
Use instance rendering for repeated objects
Reduce the number of materials
Enable LOD
Use occlusion culling

Normal Issues

Ensure Import Normals is enabled
Verify that normals are not zero
For smooth shading, use normal averaging

Animations Play Incorrectly

Verify that Import Animation is enabled
Ensure compression error values are not too high
Try disabling compression (Compress Animation = None) for testing
Check that the skeleton matches the mesh

Animation File Size Too Large

Increase Position Error, Rotation Error, Scale Error values
Use a more aggressive compression method (CurveOptimization)
Remove unused animation channels
Ensure the animation does not contain redundant keyframes