ebiten/vector/util.go

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// Copyright 2022 The Ebitengine 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 vector
import (
"image"
"image/color"
"math"
"github.com/hajimehoshi/ebiten/v2"
)
var (
whiteImage = ebiten.NewImage(3, 3)
whiteSubImage = whiteImage.SubImage(image.Rect(1, 1, 2, 2)).(*ebiten.Image)
)
func init() {
b := whiteImage.Bounds()
pix := make([]byte, 4*b.Dx()*b.Dy())
for i := range pix {
pix[i] = 0xff
}
// This is hacky, but WritePixels is better than Fill in term of automatic texture packing.
whiteImage.WritePixels(pix)
}
func drawVerticesForUtil(dst *ebiten.Image, vs []ebiten.Vertex, is []uint16, clr color.Color, antialias bool) {
r, g, b, a := clr.RGBA()
for i := range vs {
vs[i].SrcX = 1
vs[i].SrcY = 1
vs[i].ColorR = float32(r) / 0xffff
vs[i].ColorG = float32(g) / 0xffff
vs[i].ColorB = float32(b) / 0xffff
vs[i].ColorA = float32(a) / 0xffff
}
op := &ebiten.DrawTrianglesOptions{}
op.ColorScaleMode = ebiten.ColorScaleModePremultipliedAlpha
op.AntiAlias = antialias
dst.DrawTriangles(vs, is, whiteSubImage, op)
}
// StrokeLine strokes a line (x0, y0)-(x1, y1) with the specified width and color.
func StrokeLine(dst *ebiten.Image, x0, y0, x1, y1 float32, strokeWidth float32, clr color.Color, antialias bool) {
var path Path
path.MoveTo(x0, y0)
path.LineTo(x1, y1)
strokeOp := &StrokeOptions{}
strokeOp.Width = strokeWidth
vs, is := path.AppendVerticesAndIndicesForStroke(nil, nil, strokeOp)
drawVerticesForUtil(dst, vs, is, clr, antialias)
}
// DrawFilledRect fills a rectangle with the specified width and color.
func DrawFilledRect(dst *ebiten.Image, x, y, width, height float32, clr color.Color, antialias bool) {
var path Path
path.MoveTo(x, y)
path.LineTo(x, y+height)
path.LineTo(x+width, y+height)
path.LineTo(x+width, y)
vs, is := path.AppendVerticesAndIndicesForFilling(nil, nil)
drawVerticesForUtil(dst, vs, is, clr, antialias)
}
// StrokeRect strokes a rectangle with the specified width and color.
//
// clr has be to be a solid (non-transparent) color.
func StrokeRect(dst *ebiten.Image, x, y, width, height float32, strokeWidth float32, clr color.Color, antialias bool) {
var path Path
path.MoveTo(x, y)
path.LineTo(x, y+height)
path.LineTo(x+width, y+height)
path.LineTo(x+width, y)
path.Close()
strokeOp := &StrokeOptions{}
strokeOp.Width = strokeWidth
strokeOp.MiterLimit = 10
vs, is := path.AppendVerticesAndIndicesForStroke(nil, nil, strokeOp)
drawVerticesForUtil(dst, vs, is, clr, antialias)
}
// DrawFilledCircle fills a circle with the specified center position (cx, cy), the radius (r), width and color.
func DrawFilledCircle(dst *ebiten.Image, cx, cy, r float32, clr color.Color, antialias bool) {
var path Path
path.Arc(cx, cy, r, 0, 2*math.Pi, Clockwise)
vs, is := path.AppendVerticesAndIndicesForFilling(nil, nil)
drawVerticesForUtil(dst, vs, is, clr, antialias)
}
// StrokeCircle strokes a circle with the specified center position (cx, cy), the radius (r), width and color.
//
// clr has be to be a solid (non-transparent) color.
func StrokeCircle(dst *ebiten.Image, cx, cy, r float32, strokeWidth float32, clr color.Color, antialias bool) {
var path Path
path.Arc(cx, cy, r, 0, 2*math.Pi, Clockwise)
path.Close()
strokeOp := &StrokeOptions{}
strokeOp.Width = strokeWidth
vs, is := path.AppendVerticesAndIndicesForStroke(nil, nil, strokeOp)
drawVerticesForUtil(dst, vs, is, clr, antialias)
}