[Qt-interest] Problem in creating empty QGLFrameBufferObject

trinathpujari trinathpujari at tataelxsi.co.in
Thu Nov 12 05:29:29 CET 2009


Samuel Rødal wrote:
> trinathpujari wrote:
>> I want to use QGLFrameBufferObject for writing texts into
>> another LCD device.
>> But when i am creating by entering the below
>>  
>>              makeCurrent();
>>              fbo = new QGLFramebufferObject(100, 100);
>>  
>> and when i run the program some data from previous example
>> program is seen.
>> Can anybody tell how to create a empty QGLFramebufferObject so i
>> can use it for the second LCD device.
>>  
>> The example which i am trying, i am attaching here please
>> confirm if it is correct way of creating the object.
>>  
>>           makeCurrent();
>>           fbo = new QGLFramebufferObject(100, 100);
>>           setWindowTitle(tr("OpenGL framebuffers 99999999999"));
>>           fbo->bind();
>>           fbo->drawTexture(QRectF(25,25,25,25),222,GL_TEXTURE_2D);
>>           QPainter paint(fbo);
>>           paint.fillRect(25,25,25,25,QColor(Qt::red));
>>           fbo->release();
>>
>>  Thanks in Advance.....
>>
>>
>>
>> Regards
>>
>> Trinath
>
> Newly allocated OpenGL textures will typically contain random 
> uninitialized data. To clear it you could do glClearColor(0, 0, 0, 0); 
> glClear(GL_COLOR_BUFFER_BIT); after binding the fbo.
>
> -- 
> Samuel
>
Hi Samuel,

            Thanks for reply. Now i can create a QGLFrameBuffer with 
empty data means black screen.

           But just i am looking at the examples and no where i can find 
how to write texts into the buffer and displaying it.
          And how to hide the buffer from showing in the widget.
          Actually my requirements are to write some string data into 
the buffer and display it on the secondary LCD device which takes buffer 
for rendering the data.

Regards
 Trinath
 










More information about the Qt-interest-old mailing list