zoom

Documentation

Overview

zoom is a handler for dealing with zoom.

Example

package main

import (
	"github.com/omustardo/gome/camera/zoom"
	"log"
)

func main() {
	var mouseScrollY float32

	zoomer := zoom.NewScrollZoom(
		// Allow zooming out to 25% of the original size, and in to 300% of the original size.
		0.25, 3,
		// For this example, simulate getting mouse input by changing this variable.
		func() float32 { return mouseScrollY },
	)

	log.Println(zoomer.GetCurrentPercent()) // 1.0 : no change since the mouse hasn't scrolled yet.

	mouseScrollY = 30
	log.Println(zoomer.GetCurrentPercent()) // value > 1.0 : the mouse was scrolled.
}

Index

• type ScrollZoom
  • func NewScrollZoom(min, max float32, GetScrollAmount func() float32) *ScrollZoom
  • func (z *ScrollZoom) GetCurrentPercent() float32
  • func (z *ScrollZoom) Range() (min, max float32)
  • func (z *ScrollZoom) Update()
• type Zoom

Examples

• Package

Types

type ScrollZoom

type ScrollZoom struct {
	// Range of percent zoom allowed. If the range doesn't include 1.0, then the default starting zoom will be (Min+Max)/2.
	// Min zoom means zoomed out as far as possible - everything will look small. Max zoom is zoomed in as close as possible.
	Min, Max float32

	// GetScrollAmount is expected to return the amount scrolled in the last update period.
	GetScrollAmount func() float32
	// contains filtered or unexported fields
}

ScrollZoom implements Zoom. Intended for use with a camera's projection matrix. Intended to get data from a mouse scroll wheel.

func NewScrollZoom

func NewScrollZoom(min, max float32, GetScrollAmount func() float32) *ScrollZoom

NewScrollZoom creates a ScrollZoom struct. Example usage:

zoomer := zoom.NewScrollZoom(0.25, 3, // allows zooming out to 25% of the original size, and in to 300% of the original size.
  func() float32 { return mouse.Handler.Scroll().Y() },
)

func (*ScrollZoom) GetCurrentPercent

func (z *ScrollZoom) GetCurrentPercent() float32

func (*ScrollZoom) Range

func (z *ScrollZoom) Range() (min, max float32)

func (*ScrollZoom) Update

func (z *ScrollZoom) Update()

type Zoom

type Zoom interface {
	// GetCurrentPercent returns the current percent zoom. Always a positive value.
	GetCurrentPercent() float32

	// Range returns the limits of zooming in and out.
	// min is the limit of zooming out, max is the limit of zooming in.
	// For example a min of 0.25 means objects appear to be 25% of their original size when zoomed out fully.
	// A max of 3 means objects will appear to be 300% of their original size when fully zoomed in.
	Range() (min, max float32)

	// Update must be called every frame.
	Update()
}

Zoom provides handling for zooming in and out.