ebiten/geom.go

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// Copyright 2014 Hajime Hoshi
//
// 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.
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package ebiten
import (
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"github.com/hajimehoshi/ebiten/internal/affine"
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)
// GeoMDim is a dimension of a GeoM.
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const GeoMDim = affine.GeoMDim
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// A GeoM represents a matrix to transform geometry when rendering an image.
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//
// The initial value is identity.
type GeoM struct {
impl *affine.GeoM
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}
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// Reset resets the GeoM as identity.
func (g *GeoM) Reset() {
g.impl = nil
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}
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// Apply pre-multiplies a vector (x, y, 1) by the matrix.
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// In other words, Apply calculates GeoM * (x, y, 1)^T.
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// The return value is x and y values of the result vector.
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func (g *GeoM) Apply(x, y float64) (x2, y2 float64) {
return g.impl.Apply(x, y)
}
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// Element returns a value of a matrix at (i, j).
func (g *GeoM) Element(i, j int) float64 {
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a, b, c, d, tx, ty := g.impl.Elements()
switch {
case i == 0 && j == 0:
return a
case i == 0 && j == 1:
return b
case i == 0 && j == 2:
return tx
case i == 1 && j == 0:
return c
case i == 1 && j == 1:
return d
case i == 1 && j == 2:
return ty
default:
panic("ebiten: i or j is out of index")
}
}
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// Concat multiplies a geometry matrix with the other geometry matrix.
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// This is same as muptiplying the matrix other and the matrix g in this order.
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func (g *GeoM) Concat(other GeoM) {
g.impl = g.impl.Concat(other.impl)
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}
// Add is deprecated as of 1.5.0-alpha.
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// Note that this doesn't make sense as an operation for affine matrices.
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func (g *GeoM) Add(other GeoM) {
g.impl = g.impl.Add(other.impl)
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}
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// Scale scales the matrix by (x, y).
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func (g *GeoM) Scale(x, y float64) {
g.impl = g.impl.Scale(x, y)
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}
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// Translate translates the matrix by (tx, ty).
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func (g *GeoM) Translate(tx, ty float64) {
g.impl = g.impl.Translate(tx, ty)
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}
// IsInvertible returns a boolean value indicating
// whether the matrix g is invertible or not.
func (g *GeoM) IsInvertible() bool {
return g.impl.IsInvertible()
}
// Invert inverts the matrix.
// If g is not invertible, Invert panics.
func (g *GeoM) Invert() {
g.impl = g.impl.Invert()
}
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// Rotate rotates the matrix by theta.
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// The unit is radian.
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func (g *GeoM) Rotate(theta float64) {
g.impl = g.impl.Rotate(theta)
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}
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// SetElement sets an element at (i, j).
func (g *GeoM) SetElement(i, j int, element float64) {
g.impl = g.impl.SetElement(i, j, element)
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}
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// ScaleGeo is deprecated as of 1.2.0-alpha. Use Scale instead.
func ScaleGeo(x, y float64) GeoM {
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g := GeoM{}
g.Scale(x, y)
return g
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}
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// TranslateGeo is deprecated as of 1.2.0-alpha. Use Translate instead.
func TranslateGeo(tx, ty float64) GeoM {
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g := GeoM{}
g.Translate(tx, ty)
return g
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}
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// RotateGeo is deprecated as of 1.2.0-alpha. Use Rotate instead.
func RotateGeo(theta float64) GeoM {
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g := GeoM{}
g.Rotate(theta)
return g
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}