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package main
import "math"
// Camera handle view position and screen
type Camera struct {
lowerLeftCorner Vec3D
origin, horizontal, vertical Vec3D
}
// NewCamera creates a new camera
func NewCamera(vfov float64, aspect float64) Camera {
origin := Vec3D{0.0, 0.0, 0.0}
theta := DegreesToRadians(vfov)
halfHeight := math.Tan(theta / 2.0)
halfWidth := aspect * halfHeight
lowerLeftCorner := Vec3D{-halfWidth, -halfHeight, -1.0}
horizontal := Vec3D{2.0 * halfWidth, 0.0, 0.0}
vertical := Vec3D{0.0, 2.0 * halfHeight, 0.0}
return Camera{lowerLeftCorner, origin, horizontal, vertical}
}
// GetRay computes Ray given screen params
func (camera Camera) GetRay(u float64, v float64) Ray {
return Ray{
camera.origin,
AddVec3D(AddVec3D(
camera.lowerLeftCorner,
ScalarProduct(u, camera.horizontal)),
ScalarProduct(v, camera.vertical),
),
}
}
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