/
camera.go
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/
camera.go
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// Copyright 2015 Arne Roomann-Kurrik
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package twodee
import (
"github.com/go-gl/mathgl/mgl32"
)
type Camera struct {
WorldBounds Rectangle
ScreenBounds Rectangle
Projection mgl32.Mat4
Inverse mgl32.Mat4
}
func NewCamera(world Rectangle, screen Rectangle) (c *Camera, err error) {
c = &Camera{}
c.SetScreenBounds(screen)
err = c.SetWorldBounds(world)
return
}
func (c *Camera) SetScreenBounds(bounds Rectangle) {
c.ScreenBounds = bounds
}
func (c *Camera) SetWorldBounds(bounds Rectangle) (err error) {
c.WorldBounds = bounds
c.Projection = mgl32.Ortho(
bounds.Min.X(),
bounds.Max.X(),
bounds.Min.Y(),
bounds.Max.Y(),
1,
-1)
c.Inverse, err = GetInverseMatrix(c.Projection)
return
}
func (c *Camera) ScreenToWorldCoords(x, y float32) (wx, wy float32) {
// http://stackoverflow.com/questions/7692988/
var (
halfw = c.ScreenBounds.Max.X() / 2.0
halfh = c.ScreenBounds.Max.Y() / 2.0
xpct = (x - halfw) / halfw
ypct = (halfh - y) / halfh
)
return Unproject(c.Inverse, xpct, ypct)
}
func (c *Camera) WorldToScreenCoords(x, y float32) (sx, sy float32) {
var pctx, pcty = Project(c.Projection, x, y)
var halfw = c.ScreenBounds.Max.X() / 2.0
var halfh = c.ScreenBounds.Max.Y() / 2.0
sx = pctx*halfw + halfw
sy = pcty*halfh + halfh
return
}