You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: shader.go
    path of file: ./repos/ebiten/internal/builtinshader
    
    the code of the file until where you have to start completion: // 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 builtinshader

import (
	"bytes"
	"fmt"
	"sync"
	"text/template"
)

type Filter int

const (
	FilterNearest Filter = iota
	FilterLinear
)

const FilterCount = 2

type Address int

const (
	AddressUnsafe Address = iota
	AddressClampToZero
	AddressRepeat
)

const AddressCount = 3

const (
	UniformColorMBody        = "ColorMBody"
	UniformColorMTranslation = "ColorMTranslation"
)

var (
	shaders  [FilterCount][AddressCount][2][]byte
	shadersM sync.Mutex
)

var tmpl = template.Must(template.New("tmpl").Parse(`//kage:unit pixels

package main

{{if .UseColorM}}
var ColorMBody mat4
var ColorMTranslation vec4
{{end}}

{{if eq .Address .AddressRepeat}}
func adjustTexelForAddressRepeat(p vec2) vec2 {
	origin := i
    
func Fragment(dstPos vec4, srcPos vec2, color vec4) vec4 {
{{if eq .Filter .FilterNearest}}
{{if eq .Address .AddressUnsafe}}
	clr := imageSrc0UnsafeAt(srcPos)
{{else if eq .Address .AddressClampToZero}}
	clr := imageSrc0At(srcPos)
{{else if eq .Address .AddressRepeat}}
	clr := imageSrc0At(adjustTexelForAddressRepeat(srcPos))
{{end}}
{{else if eq .Filter .FilterLinear}}
	p0 := srcPos - 1/2.0
	p1 := srcPos + 1/2.0

{{if eq .Address .AddressRepeat}}
	p0 = adjustTexelForAddressRepeat(p0)
	p1 = adjustTexelForAddressRepeat(p1)
{{end}}

{{if eq .Address .AddressUnsafe}}
	c0 := imageSrc0UnsafeAt(p0)
	c1 := imageSrc0UnsafeAt(vec2(p1.x, p0.y))
	c2 := imageSrc0UnsafeAt(vec2(p0.x, p1.y))
	c3 := imageSrc0UnsafeAt(p1)
{{else}}
	c0 := imageSrc0At(p0)
	c1 := imageSrc0At(vec2(p1.x, p0.y))
	c2 := imageSrc0At(vec2(p0.x, p1.y))
	c3 := imageSrc0At(p1)
{{end}}

	rate := fract(p1)
	clr := mix(mix(c0, c1, rate.x), mix(c2, c3, rate.x), rate.y)
{{end}}

{{if .UseColorM}}
	// Un-premultiply alpha.
	// When the alpha is 0, 1-sign(alpha) is 1.0, which means division does nothing.
	clr.rgb /= clr.a + (1-sign(clr.a))
	// Apply the clr matrix.
	clr = (ColorMBody * clr) + ColorMTranslation
	// Premultiply alpha
	clr.rgb *= clr.a
	// Apply the color scale.
	clr *= color
	// Clamp the output.
	clr.rgb = min(clr.rgb, clr.a)
{{else}}
	// Apply the color scale.
	clr *= color
{{end}}

	return clr
}