Terrain

Korender supports optimized rendering of large terrain surfaces by implementing an algorithm based on the idea of Geometry Clipmaps. This algorithm allows to drastically reduce the number of triangles required to render a large terrain while minimizing visual details loss and LOD transitions. Basically, Korender draws the terrain as the series of clipmap rings centered and the viewpoint. Rings represent LOD levels - the more distant the ring is, the coarser triangles its contains. Transitions between rings are smoothed using vertex morphing, which eliminates vertex popping during viewport moving.

To render a terrain, first define terrain prefab in Korender context, then render the prefab in Frame context with terrain material modifier:

Korender {
    val terrain = clipmapTerrainPrefab(id = "terrain", cellSize = 2.0f, hg = 10, rings = 6)
    ...
    Frame {
        Renderable(
            base(...),
            terrain(
                heightTexture = texture("terrain/heightmap.png"),
                heightTextureSize = 1024,
                heightScale = 200.0f,
                outsideHeight = 0.0f,
                terrainCenter = Vec3(0f, 300f, 0f)
            ),
            prefab = terrain
        )

Prefab parameters:

• id unique identifier
• cellSize world space size of a terrain cell
• hg parameter defining ring width: the higher the value, the more geometry details will be preserved while rendering
• rings number of clipmap rings

Material modifier parameters:

• heightTexture heightmap defining height value at terrain point
• heightTextureSize size of the heightmap in pixels
• heightScale multiplier to pixel value defined by heightTexture (assuming the pixel value is 0..1)
• outsideHeight height value outside the texture extents
• terrainCenter world space point where the terrain center is to be placed

The visible terrain extent from the viewpoint is roughly 2*hg * 2^rings terrain cells