Save an opengl texture in tiff file from an other thread - c++

Question

I'm trying to save a texture in tiff file from an other thread. But the only result i get is a white picture, I think it come from the glcontext ( because it's not possible to have one glcontext for several thread). That's why i've tried to create two glcontext and share the display context. But still i don't have the gl texture. I can't get the texture from the second opengl context
. I'm tring to do that because at the end the texture will be a video stream from a camera .
Here is my context creation :
static PIXELFORMATDESCRIPTOR pfd =
{
sizeof(PIXELFORMATDESCRIPTOR), // Size Of This Pixel Format Descriptor
1, // Version Number
PFD_DRAW_TO_WINDOW | // Format Must Support Window
PFD_SUPPORT_OPENGL | // Format Must Support OpenGL
PFD_DOUBLEBUFFER, // Must Support Double Buffering
PFD_TYPE_RGBA, // Request An RGBA Format
8, // Select Our Color Depth
0, 0, 0, 0, 0, 0, // Color Bits Ignored
0, // No Alpha Buffer
0, // Shift Bit Ignored
0, // No Accumulation Buffer
0, 0, 0, 0, // Accumulation Bits Ignored
16, // 16Bit Z-Buffer (Depth Buffer)
0, // No Stencil Buffer
0, // No Auxiliary Buffer
PFD_MAIN_PLANE, // Main Drawing Layer
0, // Reserved
0, 0, 0 // Layer Masks Ignored
};
GLuint PixelFormat;
// create the pixel pixel format descriptor
PixelFormat = ChoosePixelFormat(dc, &pfd);
// set the pixel format descriptor
SetPixelFormat(dc, PixelFormat, &pfd);
gl = wglCreateContext(dc);
gl2 = wglCreateContext(dc);
wglShareLists(gl, gl2);
wglMakeCurrent(dc, gl);
GLenum g= glewInit();
wglewInit();
loadImage();
rec = new Recorder(dc,gl2);
rec->Start_StopRecord(text, true);
Here is the code to save to tiff file :
Recorder::Recorder(HDC &hdc, HGLRC &_gl)
{
isStarted = false;
dc = hdc;
gl = _gl;
}
Recorder::~Recorder()
{
if (isStarted) {
isStarted = false;
recordThread.join();
CloseTifFile();
delete mp_fileTifIn;
}
}
void Recorder::Start_StopRecord(GLuint Texture, bool launched){
if (launched) {
if (isStarted) {
wglMakeCurrent(dc, gl);
isStarted = false;
recordThread.join();
CloseTifFile();
pixels.release();
}
else {
isStarted = true;
//wglMakeCurrent(NULL, NULL);
//RecordShot(&Texture);
recordThread = std::thread(&Recorder::RecordShot, this,&Texture);
}
}
}
void Recorder::RecordShot(GLuint* texture){
wglMakeCurrent(dc, gl);
OpenTifFile(*texture);
pixels = std::unique_ptr<int>(new int[width*height]);
//while (isStarted) {
WriteTif8Bits(*texture);
WriteDirectory();
//Sleep(16);
//}
pixels.release();
}
void Recorder::OpenTifFile(GLuint &Texture){
char* filename="../test3.tiff";
glGetTexLevelParameteriv(GL_TEXTURE_2D,0,GL_TEXTURE_HEIGHT,&height);
glGetTexLevelParameteriv(GL_TEXTURE_2D,0,GL_TEXTURE_WIDTH,&width);
mp_fileTifIn = TIFFOpen(filename,"w");
}
void Recorder::CloseTifFile(){
TIFFClose(mp_fileTifIn);
}
/*
* Open Sub data for a Tiff file (allow multiple picture in one tif file)
*/
void Recorder::WriteDirectory(){
TIFFWriteDirectory(mp_fileTifIn);
}
void Recorder::WriteTif8Bits(GLuint &Texture){
//Setup Tiff Configuration
TIFFSetField(mp_fileTifIn,TIFFTAG_IMAGEWIDTH,width);
TIFFSetField(mp_fileTifIn,TIFFTAG_IMAGELENGTH,height);
TIFFSetField(mp_fileTifIn,TIFFTAG_SAMPLESPERPIXEL,4);
TIFFSetField(mp_fileTifIn,TIFFTAG_BITSPERSAMPLE,8);
TIFFSetField(mp_fileTifIn,TIFFTAG_ROWSPERSTRIP,TIFFDefaultStripSize(mp_fileTifIn,width));
TIFFSetField(mp_fileTifIn,TIFFTAG_ORIENTATION,ORIENTATION_TOPLEFT);
TIFFSetField(mp_fileTifIn,TIFFTAG_PLANARCONFIG,PLANARCONFIG_CONTIG);
TIFFSetField(mp_fileTifIn, TIFFTAG_COMPRESSION, COMPRESSION_NONE);
TIFFSetField(mp_fileTifIn, TIFFTAG_PHOTOMETRIC, PHOTOMETRIC_RGB);
glBindTexture(GL_TEXTURE_2D,Texture);
assert(glGetError() == GL_NO_ERROR);
glGetTexImage(GL_TEXTURE_2D,0,GL_RGBA,GL_UNSIGNED_BYTE,pixels.get());
assert(glGetError() == GL_NO_ERROR);
//Image Reversal
Reverse(pixels.get(), height, width);
//Write one picture
/*for (int row = 0; row < height; row++) {
TIFFWriteScanline(mp_fileTifIn, pixels.get(), row, 0);
lineChange(pixels.get(), width);
}*/
TIFFWriteEncodedStrip(mp_fileTifIn, 0, pixels.get(), height*width * sizeof(int));
}
void Recorder::lineChange(int* pointer, int width) {
pointer -= width;
}
void Recorder::Reverse(int* pointer, int height, int width) {
pointer += (height - 1) * width;
}
And here is the loadImages function
int loadImage() {
wglMakeCurrent(dc, gl);
cv::Mat image;
image = cv::imread(std::string("C:/Users/Public/Pictures/Sample Pictures/Desert.jpg"), CV_LOAD_IMAGE_COLOR);
if (!image.data)
return -1;
cvNamedWindow("try", cv::WINDOW_AUTOSIZE);
cv::imshow("try", image);
cv::flip(image, image, 0);
glGenTextures(1, &text);
GLenum g=glGetError();
glBindTexture(GL_TEXTURE_2D, text);
assert(glGetError() == GL_NO_ERROR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, image.cols, image.rows, 0, GL_BGR, GL_UNSIGNED_BYTE, image.ptr());
return 0;
}
Here is a test project where i'm loading a picture with opencv and i try to save it in an other thread : https://mega.nz/#!SBMUnJRI!dLC_l9hmCkhIDDUaygHuq4Kw2SKIuxRE7m19md74p0k
To run the project you need Opencv and glew, libtiff is already packaged inside
If you think somethink is missing for this post, i invite you to comment it before downgrade as i'm following my subject

Answer 1

I finally solved my problem by doing all opengl action in one thread ( i retrieve the image and display it in one thread, and i save it in another, which doesn't need an openglcontext)
An other thing that were confusing me is a bad configuration of
glGetTexImage(GL_TEXTURE_2D,0,GL_RGBA,GL_UNSIGNED_BYTE,this->rec[0].pixels.get());
But my textures are GL_TEXTURE_RECTANGLE_NV, that's why i had only a white picture sometimes.