mirror of
https://github.com/hajimehoshi/ebiten.git
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146 lines
3.2 KiB
Go
146 lines
3.2 KiB
Go
// Copyright 2014 Hajime Hoshi
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package affine
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import (
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"math"
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)
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// GeoMDim is a dimension of a GeoM.
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const GeoMDim = 3
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var (
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geoMIdentityElements = []float64{
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1, 0, 0,
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0, 1, 0,
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}
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)
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// A GeoM represents a matrix to transform geometry when rendering an image.
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//
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// The initial value is identity.
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type GeoM struct {
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// When elements is empty, this matrix is identity.
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// elements is immutable and a new array must be created when updating.
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elements []float64
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}
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func (g *GeoM) UnsafeElements() []float64 {
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if g.elements == nil {
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g.elements = geoMIdentityElements
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}
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return g.elements
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}
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// SetElement sets an element at (i, j).
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func (g *GeoM) SetElement(i, j int, element float64) {
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if g.elements == nil {
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g.elements = geoMIdentityElements
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}
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es := make([]float64, len(g.elements))
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copy(es, g.elements)
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es[i*GeoMDim+j] = element
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g.elements = es
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}
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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) {
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if g.elements == nil {
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g.elements = geoMIdentityElements
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}
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if other.elements == nil {
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other.elements = geoMIdentityElements
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}
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g.elements = mul(other.elements, g.elements, GeoMDim)
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}
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// Add is deprecated.
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func (g *GeoM) Add(other GeoM) {
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if g.elements == nil {
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g.elements = geoMIdentityElements
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}
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if other.elements == nil {
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other.elements = geoMIdentityElements
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}
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g.elements = add(other.elements, g.elements, GeoMDim)
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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) {
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if g.elements == nil {
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g.elements = []float64{
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x, 0, 0,
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0, y, 0,
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}
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return
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}
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es := make([]float64, len(g.elements))
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copy(es, g.elements)
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for i := 0; i < GeoMDim; i++ {
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es[i] *= x
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es[i+GeoMDim] *= y
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}
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g.elements = es
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}
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// Translate translates the matrix by (x, y).
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func (g *GeoM) Translate(tx, ty float64) {
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if g.elements == nil {
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g.elements = []float64{
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1, 0, tx,
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0, 1, ty,
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}
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return
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}
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es := make([]float64, len(g.elements))
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copy(es, g.elements)
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es[2] += tx
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es[2+GeoMDim] += ty
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g.elements = es
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}
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// Rotate rotates the matrix by theta.
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func (g *GeoM) Rotate(theta float64) {
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sin, cos := math.Sincos(theta)
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g.Concat(GeoM{
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elements: []float64{
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cos, -sin, 0,
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sin, cos, 0,
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},
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})
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}
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// ScaleGeo is deprecated as of 1.2.0-alpha. Use Scale instead.
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func ScaleGeo(x, y float64) GeoM {
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g := GeoM{}
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g.Scale(x, y)
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return g
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}
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// TranslateGeo is deprecated as of 1.2.0-alpha. Use Translate instead.
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func TranslateGeo(tx, ty float64) GeoM {
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g := GeoM{}
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g.Translate(tx, ty)
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return g
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}
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// RotateGeo is deprecated as of 1.2.0-alpha. Use Rotate instead.
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func RotateGeo(theta float64) GeoM {
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g := GeoM{}
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g.Rotate(theta)
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return g
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}
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