Tutorial 5: Decals

Decal usage
Introduction to the Mesh class

Mostly this tutorial is about DecalMeshs, which are the simplest of the Mesh classes, and a good place to start. When the meteor strikes the ground, a red crater is created at the point of impact, which fades over time. This red crater is a texture painted on the terrain itself, and is called a "Decal".

The Mesh is one of the most important primitives for a game engine - it is how objects are placed, moved, and exist in the world.

I'll point out a little hack: the Meteor class used to be "deleteable" when 'donePleaseDelete' was true. Rather than rename / clean code, the logic is changed so that donePleaseDelete must be true AND decal is null.

Tutorial 5: Change the alpha of the decal

The Decal is created (in the section below.) This checks the decal each tick and fades it out. When fully faded, the decal is deleted.

The game owns the Mesh! Not the Lilith engine. This is true of all Mesh's. The life of a Mesh:

new it (which adds it to a container)
position it in the world
delete it when done (note you don't have to remove it from the MeshContainer - this is automatic)

Tutorial 5: Create and position decal.

Most Mesh's are created from a MeshResource. Decals are unique that they take a Texture instead of a MeshResource.

const Texture* decalTexture = TextureManager::Instance()->GetTexture( "impact", 0 );
GLASSERT( decalTexture );
decal = new DecalMesh( decalTexture, 1.5f );
decal->SetPos( location, rand.FRand( 360.0f ) );

This is important code - games use lots of Meshs.

As noted, first we get the texture, then construct the DecalMesh. It looks good at about a size of 1.5x1.5 units, which is the 'size' parameter.

The SetPos() sets both the position and rotation in one call.

Conclusion

Short and adds a nice impact crater. But a good foundation for working more with Meshes.