ebiten/internal/graphicsdriver/opengl/pbo_desktop.go

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// Copyright 2019 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.
// +build darwin freebsd linux windows
// +build !js
// +build !android
// +build !ios
package opengl
import (
"reflect"
"runtime"
"unsafe"
"github.com/hajimehoshi/ebiten/internal/graphics"
)
const canUsePBO = true
type pboState struct {
image *Image
mappedPBO unsafe.Pointer
}
var thePBOState pboState
func (s *pboState) mapPBOIfNecessary(img *Image) {
if s.image == img {
return
}
s.ensurePBOUnmapped()
if img.pbo == *new(buffer) {
w, h := graphics.InternalImageSize(img.width), graphics.InternalImageSize(img.height)
img.pbo = img.driver.context.newPixelBufferObject(w, h)
}
s.image = img
s.mappedPBO = img.driver.context.mapPixelBuffer(img.pbo)
if s.mappedPBO == nil {
panic("opengl: mapPixelBuffer failed")
}
}
func (s *pboState) draw(pix []byte, x, y, width, height int) {
w, h := graphics.InternalImageSize(s.image.width), graphics.InternalImageSize(s.image.height)
var mapped []byte
sh := (*reflect.SliceHeader)(unsafe.Pointer(&mapped))
sh.Data = uintptr(s.mappedPBO)
sh.Len = 4 * w * h
sh.Cap = 4 * w * h
stride := 4 * w
offset := 4 * (y*w + x)
for j := 0; j < height; j++ {
copy(mapped[offset+stride*j:offset+stride*j+4*width], pix[4*width*j:4*width*(j+1)])
}
runtime.KeepAlive(mapped)
}
func (s *pboState) ensurePBOUnmapped() {
if s.mappedPBO == nil {
return
}
i := s.image
w, h := graphics.InternalImageSize(i.width), graphics.InternalImageSize(i.height)
i.driver.context.unmapPixelBuffer(i.pbo, i.textureNative, w, h)
s.image = nil
s.mappedPBO = nil
}