ebiten/ebitenutil/shapes.go

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// Copyright 2017 The Ebiten Authors
//
// 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.
package ebitenutil
import (
"image"
"image/color"
"math"
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"github.com/hajimehoshi/ebiten/v2"
"github.com/hajimehoshi/ebiten/v2/internal/colormcache"
)
var (
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emptyImage = ebiten.NewImage(3, 3)
emptySubImage = emptyImage.SubImage(image.Rect(1, 1, 2, 2)).(*ebiten.Image)
)
func init() {
emptyImage.Fill(color.White)
}
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// DrawLine draws a line segment on the given destination dst.
//
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// DrawLine is intended to be used mainly for debugging or prototyping purpose.
//
// DrawLine is not concurrent-safe.
func DrawLine(dst *ebiten.Image, x1, y1, x2, y2 float64, clr color.Color) {
length := math.Hypot(x2-x1, y2-y1)
op := &ebiten.DrawImageOptions{}
op.GeoM.Scale(length, 1)
op.GeoM.Rotate(math.Atan2(y2-y1, x2-x1))
op.GeoM.Translate(x1, y1)
op.ColorM = colormcache.ColorToColorM(clr)
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// Filter must be 'nearest' filter (default).
// Linear filtering would make edges blurred.
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dst.DrawImage(emptySubImage, op)
}
// DrawRect draws a rectangle on the given destination dst.
//
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// DrawRect is intended to be used mainly for debugging or prototyping purpose.
//
// DrawRect is not concurrent-safe.
func DrawRect(dst *ebiten.Image, x, y, width, height float64, clr color.Color) {
op := &ebiten.DrawImageOptions{}
op.GeoM.Scale(width, height)
op.GeoM.Translate(x, y)
op.ColorM = colormcache.ColorToColorM(clr)
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// Filter must be 'nearest' filter (default).
// Linear filtering would make edges blurred.
dst.DrawImage(emptyImage.SubImage(image.Rect(1, 1, 2, 2)).(*ebiten.Image), op)
}