Ray Tracing

Ray tracing renders your models by casting rays directly against the mathematical surface definitions, producing pixel-perfect edges and curves at any zoom level.

Why Ray Tracing?

Traditional CAD rendering converts smooth surfaces into triangle meshes (tessellation) before display. This creates visible artifacts:

• Faceted edges: Cylinders appear as hexagons, spheres look like geodesic domes
• Tessellation lag: Parameter changes require re-meshing before display
• LOD tradeoffs: Fine meshes use more memory, coarse meshes look jagged

vcad's ray tracer bypasses tessellation entirely. Each pixel casts a ray that intersects the actual mathematical surface, so curves remain perfectly smooth regardless of zoom level.

When to Use Ray Tracing

Ray tracing is ideal for:

• Precise visual inspection: Verify edge quality and surface continuity
• Presentation renders: Capture screenshots with perfect silhouettes
• High-zoom work: Examine fine details without seeing mesh artifacts
• Curved surfaces: Cylinders, spheres, cones, and tori look dramatically better

For rapid prototyping or when working with very complex assemblies, standard rendering may be more responsive.

Enabling Ray Tracing

1. Open Settings from the toolbar
2. Under Display, find Render Mode
3. Select Ray Traced

If ray tracing is unavailable (no WebGPU), the option will be disabled and vcad will use standard rendering.

Quality Settings

Three quality levels trade resolution for performance:

vcad automatically uses Draft quality while you move the camera, then switches to your selected quality when idle.

Changing Quality

1. Open Settings
2. Under Display, find Ray Trace Quality
3. Select Draft, Standard, or High

Performance Considerations

Ray tracing performance depends on several factors:

Model Complexity

More faces mean more ray intersection tests. Simple primitives render quickly; complex boolean results with many faces take longer.

Resolution

Higher quality settings render more pixels. If performance drops, try Draft or Standard quality.

GPU Capability

Ray tracing runs on WebGPU compute shaders. Discrete GPUs perform significantly better than integrated graphics.

Resolution Cap

To maintain interactivity, resolution is capped at 640x480 equivalent pixels. For very large viewports, the ray-traced image is upscaled.

Supported Surfaces

The ray tracer handles all vcad surface types:

All surfaces support trimmed boundaries (faces with holes).

Face Selection

Ray tracing enables precise face picking. When you click on the model, the ray tracer reports exactly which face is under the cursor.

This is more accurate than mesh-based picking, especially at edges where tessellation can cause incorrect selections.

Fallback Behavior

If WebGPU is unavailable, vcad automatically falls back to standard tessellated rendering. Your models still display correctly, just with the usual mesh-based quality.

To check if ray tracing is available:

1. Open Settings
2. Look for Ray Trace Quality under Display
3. If the option is disabled, your browser does not support WebGPU

Troubleshooting

Ray tracing option is disabled

Your browser does not support WebGPU. Try:

• Chrome 113 or later
• Edge 113 or later
• Enable WebGPU flags if using an older version

Rendering is slow

• Switch to Draft quality during editing
• Reduce viewport size
• Check if you have a discrete GPU available

Edges look blocky

This can happen at very high zoom if you hit the resolution cap. The ray tracer limits pixel count for interactivity. For screenshots, export at a higher resolution instead.

Comparison