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graphics.go
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graphics.go
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// Copyright 2014 Hajime Hoshi
//
// 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 ebiten
import (
"github.com/hajimehoshi/ebiten/internal/graphics/opengl"
)
// Filter represents the type of filter to be used when an image is maginified or minified.
type Filter int
const (
FilterNearest Filter = iota // nearest (crisp-edged) filter
FilterLinear // linear filter
)
func glFilter(c *opengl.Context, filter Filter) opengl.Filter {
switch filter {
case FilterNearest:
return c.Nearest
case FilterLinear:
return c.Linear
}
panic("not reach")
}
// CompositeMode represents Porter-Duff composition mode.
type CompositeMode int
// This name convention follows CSS compositing: https://drafts.fxtf.org/compositing-2/.
//
// In the above comments,
// c_src, c_dst and c_out represent alpha-premultiplied RGB values of source, destination and output respectively. α_src and α_dst represent alpha values of source and destination respectively.
const (
// Regular alpha blending
// c_out = c_src + c_dst × (1 - α_src)
CompositeModeSourceOver CompositeMode = CompositeMode(opengl.CompositeModeSourceOver)
// c_out = 0
CompositeModeClear = CompositeMode(opengl.CompositeModeClear)
// c_out = c_src
CompositeModeCopy = CompositeMode(opengl.CompositeModeCopy)
// c_out = c_dst
CompositeModeDestination = CompositeMode(opengl.CompositeModeDestination)
// c_out = c_src × (1 - α_dst) + c_dst
CompositeModeDestinationOver = CompositeMode(opengl.CompositeModeDestinationOver)
// c_out = c_src × α_dst
CompositeModeSourceIn = CompositeMode(opengl.CompositeModeSourceIn)
// c_out = c_dst × α_src
CompositeModeDestinationIn = CompositeMode(opengl.CompositeModeDestinationIn)
// c_out = c_src × (1 - α_dst)
CompositeModeSourceOut = CompositeMode(opengl.CompositeModeSourceOut)
// c_out = c_dst × (1 - α_src)
CompositeModeDestinationOut = CompositeMode(opengl.CompositeModeDestinationOut)
// c_out = c_src × α_dst + c_dst × (1 - α_src)
CompositeModeSourceAtop = CompositeMode(opengl.CompositeModeSourceAtop)
// c_out = c_src × (1 - α_dst) + c_dst × α_src
CompositeModeDestinationAtop = CompositeMode(opengl.CompositeModeDestinationAtop)
// c_out = c_src × (1 - α_dst) + c_dst × (1 - α_src)
CompositeModeXor = CompositeMode(opengl.CompositeModeXor)
// Sum of source and destination (a.k.a. 'plus' or 'additive')
// c_out = c_src + c_dst
CompositeModeLighter = CompositeMode(opengl.CompositeModeLighter)
)