mirror of
https://github.com/hajimehoshi/ebiten.git
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133 lines
3.1 KiB
Go
133 lines
3.1 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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func geoMValueString(values [GeoMDim - 1][GeoMDim]float64) string {
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b := make([]uint8, 0, (GeoMDim-1)*(GeoMDim)*8)
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for i := 0; i < GeoMDim-1; i++ {
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for j := 0; j < GeoMDim; j++ {
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b = append(b, uint64ToBytes(math.Float64bits(values[i][j]))...)
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}
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}
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return string(b)
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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 values is empty, this matrix is identity.
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values string
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}
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func (g *GeoM) dim() int {
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return GeoMDim
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}
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func (g *GeoM) Elements() []float64 {
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return elements(g.values, GeoMDim)
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}
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func (g *GeoM) element(i, j int) float64 {
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return g.Elements()[i*GeoMDim+j]
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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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g.values = setElement(g.values, GeoMDim, i, j, element)
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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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result := GeoM{}
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mul(&other, g, &result)
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*g = result
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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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result := GeoM{}
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add(&other, g, &result)
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*g = result
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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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v := elements(g.values, GeoMDim)
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for i := 0; i < GeoMDim; i++ {
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v[i] *= x
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v[i+GeoMDim] *= y
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}
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g.values = setElements(v, GeoMDim)
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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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v := elements(g.values, GeoMDim)
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v[2] += tx
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v[2+GeoMDim] += ty
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g.values = setElements(v, GeoMDim)
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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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values: geoMValueString([GeoMDim - 1][GeoMDim]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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return GeoM{
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values: geoMValueString([GeoMDim - 1][GeoMDim]float64{
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{x, 0, 0},
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{0, y, 0},
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}),
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}
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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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return GeoM{
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values: geoMValueString([GeoMDim - 1][GeoMDim]float64{
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{1, 0, tx},
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{0, 1, ty},
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}),
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}
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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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sin, cos := math.Sincos(theta)
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return GeoM{
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values: geoMValueString([GeoMDim - 1][GeoMDim]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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