ml
99 lines
2.8 KiB
Go
99 lines
2.8 KiB
Go
package levels
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import (
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"math"
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mgl "github.com/go-gl/mathgl/mgl32"
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)
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// LimitedCamera is a camera implementation with ranged controls for zooming and moving.
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type LimitedCamera struct {
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viewportWidth, viewportHeight float32
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minZoom, maxZoom float32
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minPos, maxPos float32
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requestedZoomLevel float32
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viewOffsetX, viewOffsetY float32
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viewMatrix mgl.Mat4
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}
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// NewLimitedCamera returns a new instance of a LimitedCamera.
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func NewLimitedCamera(minZoom, maxZoom float32, minPos, maxPos float32) *LimitedCamera {
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cam := &LimitedCamera{
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viewportWidth: 1.0,
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viewportHeight: 1.0,
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minZoom: minZoom,
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maxZoom: maxZoom,
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minPos: minPos,
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maxPos: maxPos,
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viewMatrix: mgl.Ident4()}
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return cam
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}
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// SetViewportSize notifies the camera how big the view is.
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func (cam *LimitedCamera) SetViewportSize(width, height float32) {
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if (cam.viewportWidth != width) || (cam.viewportHeight != height) {
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cam.viewportWidth, cam.viewportHeight = width, height
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cam.updateViewMatrix()
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}
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}
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// ViewMatrix implements the Viewer interface.
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func (cam *LimitedCamera) ViewMatrix() *mgl.Mat4 {
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return &cam.viewMatrix
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}
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// MoveBy adjusts the requested view offset by given delta values in world coordinates.
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func (cam *LimitedCamera) MoveBy(dx, dy float32) {
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cam.MoveTo(cam.viewOffsetX+dx, cam.viewOffsetY+dy)
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}
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// MoveTo sets the requested view offset to the given world coordinates.
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func (cam *LimitedCamera) MoveTo(worldX, worldY float32) {
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cam.viewOffsetX = cam.limitValue(worldX, -cam.maxPos, cam.minPos)
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cam.viewOffsetY = cam.limitValue(worldY, -cam.maxPos, cam.minPos)
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cam.updateViewMatrix()
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}
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// ZoomAt adjusts the requested zoom level by given delta, centered around given world position.
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// Positive values zoom in.
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func (cam *LimitedCamera) ZoomAt(levelDelta float32, x, y float32) {
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cam.requestedZoomLevel = cam.limitValue(cam.requestedZoomLevel+levelDelta, cam.minZoom, cam.maxZoom)
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focusPoint := mgl.Vec4{x, y, 0.0, 1.0}
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oldPixel := cam.viewMatrix.Mul4x1(focusPoint)
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cam.updateViewMatrix()
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newPixel := cam.viewMatrix.Mul4x1(focusPoint)
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scaleFactor := cam.scaleFactor()
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cam.MoveBy(-(newPixel[0]-oldPixel[0])/scaleFactor, +(newPixel[1]-oldPixel[1])/scaleFactor)
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}
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func (cam *LimitedCamera) limitValue(value float32, min, max float32) float32 {
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result := value
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if result < min {
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result = min
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}
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if result > max {
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result = max
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}
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return result
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}
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func (cam *LimitedCamera) scaleFactor() float32 {
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return float32(math.Pow(2.0, float64(cam.requestedZoomLevel)))
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}
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func (cam *LimitedCamera) updateViewMatrix() {
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scaleFactor := cam.scaleFactor()
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cam.viewMatrix = mgl.Ident4().
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Mul4(mgl.Translate3D(cam.viewportWidth/2.0, cam.viewportHeight/2.0, 0)).
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Mul4(mgl.Scale3D(scaleFactor, -scaleFactor, 1.0)).
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Mul4(mgl.Translate3D(cam.viewOffsetX, cam.viewOffsetY, 0))
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}
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