Messages

1

Window / Re: Why does SFML with an Opengl 3.0 context draw twice?

« on: April 15, 2013, 08:14:49 am »

I repeated the test without drawing the triangles and the error is the same. glClear draws the wrong color and there is still the black bar. I also tried with glClearColor set to red and in the OpenGL 3.0 context it drew magenta which again is incorrect.

I repeated the test under Arch Linux with Mesa 9.1.1 and got the same results.

I wrote another test using freeglut and glutinitcontextversion to 3.0 and there were no issues, so I think this is somehow an SFML problem.

2

Window / Why does SFML with an Opengl 3.0 context draw twice?

« on: April 14, 2013, 04:01:12 am »

I've been working on a 3D application using SFML for context creation and OpenGL 3.0. For some reason when I attempt to create the context using OpenGL 3.0 it seems to draw the image slightly narrowed and doubled with a black bar in between, and the screen seems to be cleared with green instead of red for some reason. If I change the context to 2.1 it draws normally. Originally I was having this problem using modern OpenGL code but I've provided a sample using the fixed function pipeline so that the problem is clearer.

#include <SFML/Window.hpp>
#include <SFML/OpenGL.hpp>

int main()
{
    // create the window
    sf::ContextSettings settings;
    settings.depthBits = 24;
    settings.stencilBits = 8;
    settings.antialiasingLevel = 4;
    settings.majorVersion = 3;
    settings.minorVersion = 0;

sf::Window window(sf::VideoMode(800, 600), "OpenGL", sf::Style::Default, settings);

// load resources, initialize the OpenGL states, ...
glClearColor(1.0, 0.0, 0.0, 1.0);

// run the main loop
bool running = true;
while (running)
{
    // handle events
    sf::Event event;
    while (window.pollEvent(event))
    {
        if (event.type == sf::Event::Closed)
        {
            // end the program
            running = false;
        }
    }

    // clear the buffers
    glClear(GL_COLOR_BUFFER_BIT);

    // draw...
    glBegin(GL_TRIANGLES);
    glVertex3f( 0.0, 1.0, 0.0);
    glVertex3f(-1.0,-1.0, 0.0);
    glVertex3f( 1.0,-1.0, 0.0);
    glEnd();

    // end the current frame (internally swaps the front and back buffers)
    window.display();
}

return 0;
}

If I Change these two lines:

   settings.majorVersion = 3;
   settings.minorVersion = 0;

To these:

   settings.majorVersion = 2;
   settings.minorVersion = 1;

The window draws normally.

Here are screenshots of what is happening.




The second image is a little messed up because my computer lagged. It shouldn't have that orange tone.

My setup is:

Ubuntu 12.10 Intel i7-3630QM Intel HD Graphics 4000

From glxinfo: OpenGL renderer string: Mesa DRI Intel(R) Ivybridge Mobile OpenGL version string: 3.0 Mesa 9.0.2 OpenGL shading language version string: 1.30

From lspci: Kernel driver in use: i915

I thought this might be a driver issue but I've had success running OpenGL 3.0 programs using GLUT and no deprecated functionality so it must have been creating a valid OpenGL 3.0 context and working.

I'm very confused as to why this is happening.