Terrain Editing

The terrain editor is used to create, modify, and beautify terrain in scenes, including terrain height variations, surface textures, and grass vegetation distribution.

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Creating Terrain

• Select Add → Terrain from the main menu, then place the terrain at an appropriate position in the scene.
• Adjust the terrain resolution in the Properties panel (usually should match the heightmap resolution).

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Terrain Brushes

Terrain brushes are used for WYSIWYG painting on terrain, including height modification, texture painting, and grass planting. Before using any brush, please:

• Select the terrain to edit in the scene;
• Click the edit button in the toolbar to open the terrain editing panel;

Common Brush Parameters

All types of brushes typically include some common parameters:

• Brush Shape: Can be selected from the shape list.
• Brush Size: Affects the area of effect; larger values mean wider affected areas.
• Brush Angle: Affects the rotation angle of the brush's effect on the terrain.
• Brush Strength: Affects the intensity of each stroke; larger values produce more noticeable changes.

Operation Tip: Hold down the left mouse button and drag on the terrain to paint.

Height Brush

The height brush is used to sculpt hills, valleys, plateaus, and other terrain features.

Height Brush Modes:

• Raise: Continuously increases terrain height.
• Lower: Continuously decreases terrain height.
• Smooth: Softens terrain details, eliminating sharp height changes.
• Flatten: Flattens the surrounding terrain height to match the height at the brush position.
• Thermal Erosion: Simulates mountain "dulling" caused by rock sliding.
• Hydraulic Erosion: Simulates gullies and valleys formed by water flow erosion, transport, and deposition.

Texture Brush

The texture brush is used to "paint" different surface materials on the terrain, such as: soil, grass, stone, snow, etc.

1. Terrain Coloring Principle

When rendering terrain, the engine typically uses two types of texture data:

• Detail Map:
  • "Real patterns" directly applied to the surface, such as grass blades in a lawn, particles in mud, or cracks in stone.
  • Repeated and tiled at a certain scale on the surface to represent detail texture when viewed up close.
  • Generally, one type of surface material corresponds to one diffuse map and normal map, etc.
• Splat Map (Blend Weight Texture):
  • Can be understood as a weight map that "controls which detail texture is used for which part of the ground."
  • Uses RGBA four channels:
    • R channel controls the weight of "Texture A" on the ground;
    • G channel controls "Texture B";
    • B channel controls "Texture C";
    • A channel controls "Texture D".
  • The RGBA values of each pixel determine the blend ratio of 4 textures at that location.
  • The texture brush essentially edits the channel values of these Splat textures.

2. Preparing Detail Textures

Before using the brush to paint surface textures, you need to add detail textures (currently the engine supports up to 8 detail textures per terrain).

• Import detail texture images as assets;
• Select the texture brush in the terrain editing panel;
• Drag and drop detail albedo textures from the Assets view into the Detail Albedo list;
• Drag and drop detail normal textures from the Assets view into the Detail Normal list (can be omitted if there's no normal map);

3. Painting Textures on the Surface

• Click on a texture in the Detail Albedo list;
• Adjust appropriate brush size, strength, and other parameters;
• Use the mouse to paint this texture on the terrain;

Grass Brush

The grass brush is used to batch plant grass clumps, wildflowers, and other vegetation on the terrain.

1. Preparing Grass Textures

Before painting grass, you need to add grass textures.

• Import grass texture images as assets;
• Select the grass brush in the terrain panel;
• Drag and drop grass textures from the Assets view into the Grass Textures list;

2. Painting Grass on the Surface

• Click on a grass texture in Grass Textures;
• Adjust appropriate brush size, strength, and other parameters;
• Use the mouse to paint grass on the terrain;

Erase Grass Brush

If the grass is painted too densely, you can use the erase grass brush to remove it. The operation method is the same as the grass brush.