mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-12-25 03:08:54 +01:00
118 lines
2.8 KiB
Go
118 lines
2.8 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 ebiten
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import (
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"math"
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)
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// GeometryMatrixDim is a dimension of a GeometryMatrix.
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const GeometryMatrixDim = 3
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// A GeometryMatrix 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 GeometryMatrix struct {
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initialized bool
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es [GeometryMatrixDim - 1][GeometryMatrixDim]float64
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}
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func geometryMatrixEsI() [GeometryMatrixDim - 1][GeometryMatrixDim]float64 {
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return [GeometryMatrixDim - 1][GeometryMatrixDim]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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func (g GeometryMatrix) dim() int {
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return GeometryMatrixDim
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}
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// Element returns a value of a matrix at (i, j).
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func (g GeometryMatrix) Element(i, j int) float64 {
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if !g.initialized {
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if i == j {
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return 1
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}
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return 0
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}
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return g.es[i][j]
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}
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// Concat multiplies a geometry matrix with the other geometry matrix.
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func (g *GeometryMatrix) Concat(other GeometryMatrix) {
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if !g.initialized {
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g.es = geometryMatrixEsI()
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g.initialized = true
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}
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result := GeometryMatrix{}
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mul(&other, g, &result)
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*g = result
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}
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// Add adds a geometry matrix with the other geometry matrix.
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func (g *GeometryMatrix) Add(other GeometryMatrix) {
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if !g.initialized {
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g.es = geometryMatrixEsI()
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g.initialized = true
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}
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result := GeometryMatrix{}
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add(&other, g, &result)
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*g = result
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}
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// SetElement sets an element at (i, j).
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func (g *GeometryMatrix) SetElement(i, j int, element float64) {
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if !g.initialized {
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g.es = geometryMatrixEsI()
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g.initialized = true
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}
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g.es[i][j] = element
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}
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// ScaleGeometry returns a matrix that scales a geometry matrix by (x, y).
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func ScaleGeometry(x, y float64) GeometryMatrix {
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return GeometryMatrix{
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initialized: true,
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es: [2][3]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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// TranslateGeometry returns a matrix taht translates a geometry matrix by (tx, ty).
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func TranslateGeometry(tx, ty float64) GeometryMatrix {
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return GeometryMatrix{
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initialized: true,
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es: [2][3]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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// RotateGeometry returns a matrix that rotates a geometry matrix by theta.
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func RotateGeometry(theta float64) GeometryMatrix {
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sin, cos := math.Sincos(theta)
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return GeometryMatrix{
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initialized: true,
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es: [2][3]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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