func gatherBuildingsPositions(
rendererPositions map[world.ModelId]Positions,
buildings world.Buildings,
offsetX, offsetY float64,
defaultR *glm.Matrix4, // Can be nil.
worldToEye glm.Matrix4,
) {
for coords, building := range buildings {
position := glm.Vector3{
float64(coords.X) + offsetX,
float64(coords.Y) + offsetY,
0,
}.Translation()
facer, ok := building.(world.Facer)
if ok {
// We obey the facing of the buildings that have one.
r := glm.RotZ(float64(90 * facer.Facing().Value()))
position = position.Mult(r)
} else {
// Buildings without facing receive the provided default facing.
// It is given as a precalculated rotation matrix `defaultR`.
position = position.Mult(*defaultR)
}
position = worldToEye.Mult(position) // Shaders work in view space.
rendererID := building.Model()
positions := rendererPositions[rendererID]
positions = append(positions, position)
rendererPositions[rendererID] = positions
}
}
func viewMatrix(pos world.Position) (glm.Matrix4, glm.Matrix4) {
const eyeZ = .5
Rd := glm.RotZ(float64(-90 * pos.F.Value()))
Td := glm.Vector3{float64(-pos.X), float64(-pos.Y), -eyeZ}.Translation()
Ri := glm.RotZ(float64(90 * pos.F.Value()))
Ti := glm.Vector3{float64(pos.X), float64(pos.Y), eyeZ}.Translation()
Vd := Rd.Mult(Td) // Direct.
Vi := Ti.Mult(Ri) // Inverse.
return Vd, Vi
}