mirror of
https://github.com/hajimehoshi/ebiten.git
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42 lines
1.2 KiB
Go
42 lines
1.2 KiB
Go
// Copyright 2022 The Ebitengine Authors
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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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//go:build ignore
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// Reference: a public domain CRT effect
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// https://github.com/libretro/glsl-shaders/blob/master/crt/shaders/crt-lottes.glsl
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package main
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func Warp(pos vec2) vec2 {
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const (
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warpX = 0.031
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warpY = 0.041
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)
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pos = pos*2 - 1
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pos *= vec2(1+(pos.y*pos.y)*warpX, 1+(pos.x*pos.x)*warpY)
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return pos/2 + 0.5
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}
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func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
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// Adjust the texture position to [0, 1].
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pos := texCoord
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origin, size := imageSrcRegionOnTexture()
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pos -= origin
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pos /= size
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pos = Warp(pos)
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return imageSrc0At(pos*size + origin)
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}
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