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Author Topic: OpenTK and SFML  (Read 10945 times)

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Raptor2277

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OpenTK and SFML
« on: May 14, 2016, 11:17:50 pm »
Having a hard time getting sfml to work with opentk. I am creating an sfml window and trying to draw a 3d cube using opengl while using sfml's Text classes to draw text on top. However, on window.resize it bugs the program out. I am changing the model-view and setting the view-port, then it bugs the program where the cube is no longer being drawn. Also when I try to render Text, it is really buggy and flashy.

Am I doing something fundamentally wrong here?


using System;
using SFML.Window;
using SFML.Graphics;
using OpenTK.Graphics.OpenGL;
using OpenTK;

namespace SFML.NET_2015
{
    class Program
    {
        static void Main(string[] args)
        {
            ContextSettings contextSettings = new ContextSettings(24, 0, 0);
            SFML.Graphics.RenderWindow win = new RenderWindow(new VideoMode(640, 400), "SFML.NET", Styles.Default, contextSettings);
            win.SetFramerateLimit(144);
            win.SetMouseCursorVisible(true);

            win.Closed += (o, e) => { win.Close(); };
            win.Resized += (o, e) =>
            {
                GL.Viewport(0, 0, (int)win.Size.X, (int)win.Size.Y);
                Matrix4 matr = OpenTK.Matrix4.CreatePerspectiveFieldOfView((float)Math.PI * 50f / 180f, win.Size.X / (float)win.Size.Y, .1f, 10f);
                GL.LoadMatrix(ref matr);
            };


            Toolkit.Init();
            OpenTK.Graphics.GraphicsMode graphicsMode = new OpenTK.Graphics.GraphicsMode(32, (int)contextSettings.DepthBits, (int)contextSettings.StencilBits, (int)contextSettings.AntialiasingLevel);
            OpenTK.Platform.IWindowInfo windowInfo = OpenTK.Platform.Utilities.CreateWindowsWindowInfo(win.SystemHandle);
            OpenTK.Graphics.GraphicsContext context = new OpenTK.Graphics.GraphicsContext(graphicsMode, windowInfo);
            context.MakeCurrent(windowInfo);
            context.LoadAll();

            GL.EnableClientState(ArrayCap.VertexArray);

            GL.MatrixMode(MatrixMode.Projection);
            Matrix4 mat = OpenTK.Matrix4.CreatePerspectiveFieldOfView((float)Math.PI * 50f / 180f, win.Size.X / (float)win.Size.Y, .1f, 10f);
            GL.LoadMatrix(ref mat);

            GL.MatrixMode(MatrixMode.Modelview);
            GL.Translate(0, 0, -4);

            #region Verts
            float[] verts =
            {
                -1.0f,-1.0f,-1.0f, // triangle 1 : begin
    -1.0f,-1.0f, 1.0f,
    -1.0f, 1.0f, 1.0f, // triangle 1 : end
    1.0f, 1.0f,-1.0f, // triangle 2 : begin
    -1.0f,-1.0f,-1.0f,
    -1.0f, 1.0f,-1.0f, // triangle 2 : end
    1.0f,-1.0f, 1.0f,
    -1.0f,-1.0f,-1.0f,
    1.0f,-1.0f,-1.0f,
    1.0f, 1.0f,-1.0f,
    1.0f,-1.0f,-1.0f,
    -1.0f,-1.0f,-1.0f,
    -1.0f,-1.0f,-1.0f,
    -1.0f, 1.0f, 1.0f,
    -1.0f, 1.0f,-1.0f,
    1.0f,-1.0f, 1.0f,
    -1.0f,-1.0f, 1.0f,
    -1.0f,-1.0f,-1.0f,
    -1.0f, 1.0f, 1.0f,
    -1.0f,-1.0f, 1.0f,
    1.0f,-1.0f, 1.0f,
    1.0f, 1.0f, 1.0f,
    1.0f,-1.0f,-1.0f,
    1.0f, 1.0f,-1.0f,
    1.0f,-1.0f,-1.0f,
    1.0f, 1.0f, 1.0f,
    1.0f,-1.0f, 1.0f,
    1.0f, 1.0f, 1.0f,
    1.0f, 1.0f,-1.0f,
    -1.0f, 1.0f,-1.0f,
    1.0f, 1.0f, 1.0f,
    -1.0f, 1.0f,-1.0f,
    -1.0f, 1.0f, 1.0f,
    1.0f, 1.0f, 1.0f,
    -1.0f, 1.0f, 1.0f,
    1.0f,-1.0f, 1.0f
            };
            #endregion

            int buff = GL.GenBuffer();
            GL.BindBuffer(BufferTarget.ArrayBuffer, buff);
            GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(verts.Length * sizeof(float)), verts, BufferUsageHint.StaticDraw);

            GL.VertexPointer(3, VertexPointerType.Float, 3 * sizeof(float), 0);

            Text t = new Text("Hello Cube", new Font("andyb.ttf"));
            t.Position = new System.Vector2f(200, 200);

            while (win.IsOpen)
            {
                win.DispatchEvents();

                GL.Rotate(.1f, 0, 1, 0);
                GL.DrawArrays(OpenTK.Graphics.OpenGL.PrimitiveType.Triangles, 0, verts.Length);
                GL.End();

                win.PushGLStates();
                win.Draw(t);
                win.PopGLStates();

                win.Display();
            }
        }
    }
}


 
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eXpl0it3r

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AW: OpenTK and SFML
« Reply #1 on: May 16, 2016, 12:14:41 pm »
Are you sure you set the view correctly with OpenGL?
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dabbertorres

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Re: OpenTK and SFML
« Reply #2 on: May 16, 2016, 05:12:10 pm »
You're forgetting to change MatrixMode to Projection in win.Resized. Right now, your Resized event is setting the View matrix.
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Raptor2277

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Re: OpenTK and SFML
« Reply #3 on: May 16, 2016, 08:44:38 pm »
 Thanks, the resizing works now. That's a dumb mistake by me. But trying to render the text now doesn't draw the  cube. I've tried resetting the model-view and projection on each draw, but that doesn't work either.
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dabbertorres

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Re: OpenTK and SFML
« Reply #4 on: May 16, 2016, 10:12:24 pm »
I don't think you should be calling glEnd() at all. Especially since you don't even call glBegin() anywhere. glBegin() and glEnd() are for defining single vertices to draw together.

And I believe you need a call to glClear() before drawing anything (glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) usually suffices).
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Raptor2277

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Re: OpenTK and SFML
« Reply #5 on: May 16, 2016, 11:43:58 pm »
I've changed that, that was left over when I was doing immediate drawing. Calling GL.CLear() or window.clear() doesnt seem to make a difference.
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Raptor2277

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Re: OpenTK and SFML
« Reply #6 on: May 16, 2016, 11:46:23 pm »
Just do clarify, I draw the cube without trying to draw the text and it draws the cube fine, it rotates, all is good. But as soon as I do win.Draw(t); (drawing the text), the cube disappears.
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dabbertorres

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Re: OpenTK and SFML
« Reply #7 on: May 17, 2016, 06:17:24 am »
Hmm. That sounds like states or matrices being changed... Oh. What happens if you add your
            GL.MatrixMode(MatrixMode.Modelview);
            GL.Translate(0, 0, -4);
before your GL.Rotate() in your while loop?

If that doesn't fix anything, can you post the current code?

(Sorry for the laggy responses, I only have time to check the forums between classes and work. :) )
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Raptor2277

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Re: OpenTK and SFML
« Reply #8 on: May 18, 2016, 05:52:21 am »
Here is the full code. Adding the -4 translation didn't do anything.


using System;
using SFML.Window;
using SFML.Graphics;
using OpenTK.Graphics.OpenGL;
using OpenTK;

namespace SFML.NET_2015
{
    class Program
    {
        static void Main(string[] args)
        {
            ContextSettings contextSettings = new ContextSettings(24, 0, 0);
            SFML.Graphics.RenderWindow win = new RenderWindow(new VideoMode(640, 400), "SFML.NET", Styles.Default, contextSettings);
            win.SetFramerateLimit(144);
            win.SetMouseCursorVisible(true);

            win.Closed += (o, e) => { win.Close(); };
            win.Resized += (o, e) =>
            {
                GL.Viewport(0, 0, (int)win.Size.X, (int)win.Size.Y);
                GL.MatrixMode(MatrixMode.Projection);
                Matrix4 matr = OpenTK.Matrix4.CreatePerspectiveFieldOfView((float)Math.PI * 50f / 180f, win.Size.X / (float)win.Size.Y, .1f, 10f);
                GL.LoadMatrix(ref matr);
            };


            Toolkit.Init();
            OpenTK.Graphics.GraphicsMode graphicsMode = new OpenTK.Graphics.GraphicsMode(32, (int)contextSettings.DepthBits, (int)contextSettings.StencilBits, (int)contextSettings.AntialiasingLevel);
            OpenTK.Platform.IWindowInfo windowInfo = OpenTK.Platform.Utilities.CreateWindowsWindowInfo(win.SystemHandle);
            OpenTK.Graphics.GraphicsContext context = new OpenTK.Graphics.GraphicsContext(graphicsMode, windowInfo);
            context.MakeCurrent(windowInfo);
            context.LoadAll();

            GL.EnableClientState(ArrayCap.VertexArray);

            #region Verts
            float[] verts =
            {
                -1.0f,-1.0f,-1.0f, // triangle 1 : begin
    -1.0f,-1.0f, 1.0f,
    -1.0f, 1.0f, 1.0f, // triangle 1 : end
    1.0f, 1.0f,-1.0f, // triangle 2 : begin
    -1.0f,-1.0f,-1.0f,
    -1.0f, 1.0f,-1.0f, // triangle 2 : end
    1.0f,-1.0f, 1.0f,
    -1.0f,-1.0f,-1.0f,
    1.0f,-1.0f,-1.0f,
    1.0f, 1.0f,-1.0f,
    1.0f,-1.0f,-1.0f,
    -1.0f,-1.0f,-1.0f,
    -1.0f,-1.0f,-1.0f,
    -1.0f, 1.0f, 1.0f,
    -1.0f, 1.0f,-1.0f,
    1.0f,-1.0f, 1.0f,
    -1.0f,-1.0f, 1.0f,
    -1.0f,-1.0f,-1.0f,
    -1.0f, 1.0f, 1.0f,
    -1.0f,-1.0f, 1.0f,
    1.0f,-1.0f, 1.0f,
    1.0f, 1.0f, 1.0f,
    1.0f,-1.0f,-1.0f,
    1.0f, 1.0f,-1.0f,
    1.0f,-1.0f,-1.0f,
    1.0f, 1.0f, 1.0f,
    1.0f,-1.0f, 1.0f,
    1.0f, 1.0f, 1.0f,
    1.0f, 1.0f,-1.0f,
    -1.0f, 1.0f,-1.0f,
    1.0f, 1.0f, 1.0f,
    -1.0f, 1.0f,-1.0f,
    -1.0f, 1.0f, 1.0f,
    1.0f, 1.0f, 1.0f,
    -1.0f, 1.0f, 1.0f,
    1.0f,-1.0f, 1.0f
            };
            #endregion

            int buff = GL.GenBuffer();
            GL.BindBuffer(BufferTarget.ArrayBuffer, buff);
            GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(verts.Length * sizeof(float)), verts, BufferUsageHint.StaticDraw);
            GL.VertexPointer(3, VertexPointerType.Float, 3 * sizeof(float), 0);

            Text t = new Text("Hello Cube", new Font("andyb.ttf"));
            t.Position = new System.Vector2f(200, 000);

            while (win.IsOpen)
            {
                win.DispatchEvents();

                //win.Clear();
                GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);

                //GL.Viewport(0, 0, (int)win.Size.X, (int)win.Size.Y);
                GL.MatrixMode(MatrixMode.Projection);
                Matrix4 matr = OpenTK.Matrix4.CreatePerspectiveFieldOfView((float)Math.PI * 50f / 180f, win.Size.X / (float)win.Size.Y, .1f, 10f);
                GL.LoadMatrix(ref matr);

                GL.MatrixMode(MatrixMode.Modelview);
                GL.LoadIdentity();
                GL.Translate(0, 0, -4);
                GL.Rotate(50f, 0, 1, 0);

                GL.DrawArrays(OpenTK.Graphics.OpenGL.PrimitiveType.Triangles, 0, verts.Length);

                win.PushGLStates();
                win.Draw(t);
                win.PopGLStates();

                win.Display();
            }
        }
    }
}


 
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Raptor2277

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Re: OpenTK and SFML
« Reply #9 on: May 18, 2016, 05:53:34 am »
Without the

                win.PushGLStates();
                win.Draw(t);
                win.PopGLStates();

 

It draws the cube, rotated so an edge faces the screen.
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dabbertorres

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Re: OpenTK and SFML
« Reply #10 on: May 18, 2016, 11:41:14 pm »
Alright, I got it working over here.

(click to show/hide)

Two things:
You were having two contexts: one from SFML, and the one you created with OpenTK. Apparently, passing ContextHandle.Zero to the GraphicsContext constructor makes OpenTK find the already-existing context (from SFML in this case). A little nicer than manually doing so with a P/Invoke to wglGetCurrentContext (What I did in the first place!). I'm not certain if this was the issue (or part of it), but I could see it potentially causing complications in the future.

The part I am certain was at least part of the issue was coming from your cube's vertex buffer still being bound when SFML tries to draw. I haven't ever dug through enough of SFML's internals to know what it does that would make this an issue, but, in the future, make sure to unbind your buffers (pass 0 as the buffer id for glBindBuffer) before drawing with SFML (and can be a good thing to do anyways).

Beyond that, I think that was all I changed!

PS: You can also move your projection and view matrix code out of your while loop, and before it now, if you wish:
(click to show/hide)
« Last Edit: May 18, 2016, 11:45:51 pm by dabbertorres »
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Raptor2277

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Re: OpenTK and SFML
« Reply #11 on: May 19, 2016, 07:06:37 am »
I get a an AccessViolcationException when I use


            Toolkit.Init();
            OpenTK.Graphics.GraphicsContext context = new OpenTK.Graphics.GraphicsContext(ContextHandle.Zero, OpenTK.Platform.Utilities.CreateWindowsWindowInfo(win.SystemHandle));
            context.LoadAll();

 


this is the exact error:
An unhandled exception of type 'System.AccessViolationException' occurred in OpenTK.dll

Additional information: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

This issue is disused in http://en.sfml-dev.org/forums/index.php?topic=18276.0 forum. This is the only way I found to solve that problem.
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Raptor2277

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Re: OpenTK and SFML
« Reply #12 on: May 19, 2016, 07:11:21 am »
I tried you code(pasted) and replaced you context creation with what I originally had. It shows the cube for a split second, then it goes away. I guess its the context creation that is messing me up. I just can't find much on why its giving me that error.
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dabbertorres

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Re: OpenTK and SFML
« Reply #13 on: May 19, 2016, 09:53:27 am »
Well huh. Of course it wasn't that easy. Very odd that it seems to vary by computer too. Have you put a breakpoint on those lines? Can you determine which function call causes the issue? I'm wondering if it's a race condition. Or varies by graphics hardware/driver.

What graphics card and driver are you running this on?

Also, what OpenTK dlls are you using? I was testing with the dlls distributed with SFML.NET.
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Raptor2277

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Re: OpenTK and SFML
« Reply #14 on: May 19, 2016, 06:47:40 pm »
It crashes on the first(ish) GL.* call. Int his calse it was GL. Clear(), the other case I had was GL.TexImage2D. I have a GTX 970 with 365.19. I am also using the dlls handed by SFML.NET
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