OpenTK - Forums

Shadow mapping in OpenTK

imike901224 — Thu, 17 May 2012 05:48:34 -0700

I want to know how to use Shadow mapping in OpenTK. Can you give me a simple example on that? I am new here and I need some help. Thanks a lot!

spammers

avc81 — Thu, 28 Apr 2011 03:09:30 -0700

there are a lot of spambots (or spamhumans ;)) in the forum and the spam filter is checking all my posts. is the same happening to all of you?

Signed up simply because...

Zoolander — Mon, 06 Feb 2012 19:56:51 -0800

I thought a thanks was in order. OpenTK is fantastic, coming from a C/C++ background I think C# is amazing and I love how easy the switch to C# for OpenGL apps has been using OpenTK. I've been working in C# using OpenTK for about a year now, and I can't speak highly enough of it, it's made my personal projects that much more enjoyable to work on.

Thank you :)

Mouse capturing

jyc — Sat, 21 Apr 2012 16:18:04 -0700

Hello,

I've looked at the previous mouse capture threads, but none of them seem to work on Windows 7 x64 with the latest nightly (from 3-15).

I've tried to roll my own solution:

        protected override void OnLoad(EventArgs e)
        {
            base.OnLoad(e);
 
            GL.ClearColor(0.1f, 0.2f, 0.5f, 0.0f);
            GL.Enable(EnableCap.DepthTest);
 
            Mouse.Move += new EventHandler<MouseMoveEventArgs>(onMouseMoveHandler);
        }
 
        private void onMouseMoveHandler(object sender, MouseMoveEventArgs e)
        {
            MouseState current = OpenTK.Input.Mouse.GetState(0);
            Console.WriteLine(current.X);
 
            if ((prevMouseX != current.X || prevMouseY != current.Y)
                && this.Focused)
            {
                OpenTK.Input.Mouse.SetPosition(0, 0);
            }
 
            prevMouseX = current.X;
            prevMouseY = current.Y;
        }

The problem with this is that when I click on the title bar, of the application, the application is moved to the bottom of the screen.

Nvidia Compatibility - please help me

ultradr3mer — Tue, 15 May 2012 12:12:48 -0700

Ok here is what i have:

video:
http://www.youtube.com/watch?v=LZkGLiqhJV0

And as the title says its refusing to run correctly under nvidia.
Creating VAO's fails for every object using Normals.

I think it stopped working when i separated VAO and VBO generation.

Im not posting code snippets because I don't think the problem can be solved this way.
Instead ill give you the full source.
SOURCE

I would be really thankful if someone can help me out.

Linux

objarni — Thu, 29 Nov 2007 00:55:22 -0800

Installing Mono

If you are using a recent Linux distribution, all prerequisites for OpenTK projects should be readily available: the Mono runtime and the Mono compilers. Execute "mono --version" and "gmcs --version" and check if the output looks like this:

$ mono --version
Mono JIT compiler version 1.2.6 (tarball)
Copyright (C) 2002-2007 Novell, Inc and Contributors. www.mono-project.com
        TLS:           __thread
        GC:            Included Boehm (with typed GC)
        SIGSEGV:       altstack
        Notifications: epoll
        Architecture:  amd64
        Disabled:      none
 
$ gmcs --version
Mono C# compiler version 1.2.6.0

Vb.net and there problems

Fremder — Mon, 28 Nov 2011 04:24:40 -0800

Hello -
i working 99% with vb.net verry good
begining opengl with tao. ... wrapper

and see in the last weeks tao = OLD
OpenTK its NEW (and better !?)
-> for me importend for the tuture .. ok i GO to OpenTK

BUT the last 10 days i search and search and testing and downloading and and and

nothing for VB or its (sorry ) bullshit ...

then i go to backtotheroots and hope i make a good beginn with simple "beginn"

but after 3 hours its come this:

Vector3.Multiply(ParticleAttributes(i).Direction, CSng(e.Time), temp) ' OK

Vector3.add(VBO(i).Position, temp, VBO(i).Position) ' NOT OK

in c# its with "REF"

but in vb i have no idea ...

=========================

and now my simple ask :-)

its OpenTK AND VB a good think or not ?

i found 2 samples ~OpenTK and VB.net~ but NOT ONE its going without errors (not t corect Classes / imports etc.)

sorry for my english :-)

=======
the Samples from openTK its nice ... but when i convert to vb.net not going *g*
=======

with TAO i have a good "learningsample" and verry fast in vb.net
but convert to openTk its to hard for me :-(

QuickFont load font turns the screen blank.

JurgenRoeland — Fri, 30 Mar 2012 14:07:04 -0700

Hi, I'm quite new to OpenGL.

I have written an application that makes a geographic mapping in c# using openTK opengl.
It works quite well and now it became necessary to add text on my screen for some labels.

I used quickfont library. added it as subproject and reference, added the font folder to my project.
what happens now is that whenever I try to load a font, all my screen goes black. My other drawings dissapear.
I'm not even using a print method to put anything on my screen.
the font seems to load ok, as I get a pointer and the data seems to be filled in.
I tried with loading various different fonts and always get the same result, my screen goes black. removing the font declaration and all comes back

this is what I add

controlsText = new QFont("Fonts/HappySans.ttf", 16);

controlsText being declared earlier in the members as QFont.

Does somebody have an idea in what direction I have to search why the drawing goes blank ?

pictures show before and after

thanks in advance,

J. Roeland

VBO Example

JTalton — Thu, 26 Jun 2008 18:08:42 -0700

I wanted to play with vertex arrary buffers so I took a look at the VBO example code.
It only setup a single vertex array and I wanted to know how to specify normals or texture coordinates

I updated it to use a vertex array, normal array, texture array, and color array.

I then started wondering about dynamically updating the VBO so I added some methods to update the VBO from both the source array with the BufferData call and with getting and modifying the data from the VBO using MapBuffer.

I have uploaded the source if anyone is interested or if it would be good to have in the OpenTK examples.

As for performance, what do people suggest for updating an existing VBO? Copying over new data with BufferData or updating the data with MapBuffer? With MapBuffer you get an IntPtr back so I ended up wrapping it in unsafe so that I could work with the data.

OpenGL-OpenTK rotation problem

robjons21 — Mon, 14 May 2012 15:47:52 -0700

I'm a real noob who just started learning 3d programming and i have a really hard time learning about rotation in 3D space. My problem is that I can't seem to figure out how to rotate an object using it's local coordinates.

I have a basic class for 3d objects and, for starters, i want to implement functions that will rotate the object on a certain axis with x degrees. So far i have the following:

 public void RollDeg(float angle)
    {
        this.rotation = Matrix4.Mult(rotation, 
            Matrix4.CreateRotationX(MyMath.Conversions.DegToRad(angle)));
    }
 
    public void PitchDeg(float angle)
    {
        this.rotation = Matrix4.Mult(rotation, 
             Matrix4.CreateRotationY(MyMath.Conversions.DegToRad(angle)));
    }
 
    public void YawDeg(float angle)
    {
        this.rotation = Matrix4.Mult(rotation,
             Matrix4.CreateRotationZ(MyMath.Conversions.DegToRad(angle)));
    }

'rotation' is a 4x4 matrix which starts as the identity matrix. Each time i want to roll/pitch/yaw the object, i call one of the functions above.

Terrain/Mesh LOD

XZibit — Sun, 13 May 2012 16:47:30 -0700

Hey

i was working on some terrain using it for a large area. Now i cutted my terrain into pieces of
500x500 pixel heightmaps to render them more effiicient. To get most performance i just need
to implement any kind of LOD algorithm. First i dont want to use shaders but opperate by myselfe
on the cpu.

What is the best LOD to take for my terrain and for any other mesh?
Does anyone has an example implementation so that i could play arround with it?

Thank you!

OpenTK - Consider donating!

thorrablot — Tue, 06 Dec 2011 07:40:18 -0800

OpenTK users,

A number of forum posts have been asking why OpenTK doesn't have a prominent "donate" button, and I noticed that there is a Paypal-based one at the SourceForge project site.

If you've found OpenTK as useful and high-quality as I have for your .NET/Mono apps, show your appreciation with a donation! If you're a developer using OpenTK in a commercial application, talk to your boss about having your organization make a donation.

As it says on the donation page:

OpenTK is free to use but costs real money to develop and support. If you feel this project is worth it, consider donating a small amount to help it along. Every little bit counts!

context.MakeCurrent issues

miffe — Fri, 11 May 2012 07:19:42 -0700

I'm having troubles with MakeCurrent on contexts, the code below is a boild down example of what I'm trying to do.

            OpenTK.Graphics.IGraphicsContext context;
 
            using (var win = new OpenTK.NativeWindow())
            {
                context = new OpenTK.Graphics.GraphicsContext(OpenTK.Graphics.GraphicsMode.Default, win.WindowInfo);
                context.MakeCurrent(win.WindowInfo);
                context.LoadAll();
                context.MakeCurrent(null);
            }
 
            using (var win = new OpenTK.NativeWindow())
            {
                context.MakeCurrent(win.WindowInfo);
                context.MakeCurrent(null);
            }

The context.MakeCurrent(win.WindowInfo) in the second using block throws an exception saying: Failed to make context 65537 current. Error: 2000
Error 2000 means Invalid Pixel Format.

Is this not how you are supposed to manage contexts? What I'm i doing wrong?

Matrix implementation, class or structure?

migueltk — Thu, 10 May 2012 09:12:42 -0700

Matrix, class or structure?

I wonder if there is any reason to implement an array as a structure type.

In principle I think it's more a problem than an advantage. For example:

Given the following code ...

 
    public partial class Form1 : Form
    {
        Entity[] entities = new Entity[10];
        public Form1()
        {
            InitializeComponent();
 
            for (int cont = 0; cont < 10; cont++)
                entities[cont] = new Entity();
 
            foreach (Entity e in entities)
            {
                Matrix m = e.Transform; // first copy (16 values)
                Modification(ref m);
                e.Transform = m; // second copy (16 values)
            }
        }
 
        void Modification(ref Matrix m)
        {
            m.m1 = 1;
        }
    }
 
    struct Matrix
    {
        public int m1; public int m9;
        public int m2; public int m10;
        public int m3; public int m11;
        public int m4; public int m12;
        public int m5; public int m13;
        public int m6; public int m14;
        public int m7; public int m15;
        public int m8; public int m16;
    }

VBO (on Windows) vs (on Ubuntu)

ifan — Thu, 03 May 2012 11:35:44 -0700

Hello Folks,
My problem is the following:

I have a struct, which is a base of each vertices, which looks something like this.

public struct VertexPositionNormalTangentTexture
    {
        public Vector3 point;
        public Vector3 normal;
        public Vector3 tangent;
        public Vector2 texCoord;
   }

at some point of my code i use

VertexPositionNormalTangentTexture[] array = .....
GL.BufferData(.., .., .., array, ..)

My experience on Windows:
My stuff drawn looks fancy

My experience on Ubuntu:
The points are misaligned (like Point and Tangent or Normal or even Texture bits were swapped for SOME of the points)
(Or the Stride is bad somehow)
No correct triangles formed! A pile of mess displayed.

Is this the proper way to triangle strip in openGL?

tonysidus — Tue, 08 May 2012 08:30:44 -0700

I am using openTK and want to make a terrain using triangle strips. Is this right? The output is okay I just want to make sure its drawing properly.

int stepSize = 2;
int MapSize = 32;
GL.Begin(BeginMode.TriangleStrip);
for (int bx = 0; bx < MapSize + 1; bx += stepSize)
{
for (int bz = 0; bz < MapSize + 1; bz += stepSize)
{
GL.Vertex3(bx, 0, bz);
GL.Vertex3(bx, 0, bz + stepSize);
GL.Vertex3(bx + stepSize, 0, bz);
GL.Vertex3(bx + stepSize, 0, bz + stepSize);
}
}
GL.End();

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Screen coordinates to Object coordinates without gluUnProject

samssonart — Tue, 01 May 2012 13:56:31 -0700

I've been looking the forums and checked online tutorials, I want to know how can I convert screen coordinates to object coordinates, so I can draw objects using the mouse. I've seen many solutions to this, but all of them use the Glu.unproject function, which appears to be deprecated. So I want to know if anyone knows of another way to do this that won't rely on deprecated code.

[Solved Mostly]Can't read joystick properly

Tal — Sun, 06 Jun 2010 12:37:33 -0700

Here is my Joystick test(part of a GameWindow code and I use VS debugger):

protected override void OnUpdateFrame(FrameEventArgs e)
{
    base.OnUpdateFrame(e);
 
    if (Keyboard[Key.Escape])
        Exit();
    int cont = Joysticks[0].Button.Count;
    for (int i = 0; i < cont; i++ )
        if (Joysticks[0].Button[i])
            throw (new Exception());
}

As you can guess by the title, no exeption is thrown when I push all the buttons!
I also check that the I have one and only one joystick by this test:

protected override void OnUpdateFrame(FrameEventArgs e)
{
    base.OnUpdateFrame(e);
 
    if (Keyboard[Key.Escape])
        Exit();
 
    int cont = Joysticks.Count;
    if (cont == 1)
        throw (new Exception());
}

And as you can guess, the exeption was thrown.
(Please don't critic me about my tests that they are'nt like NUnit and etc. :-) )
My joystick is made by Xcom and it looks like a standard Playstation's joystick. Here is a picture of it(sorry about the size):

It's fully supported by DirectX, and I play TrackMania with it without problems.

dragging the line segment by selecting the vertex

mahantesh — Mon, 23 Apr 2012 21:42:06 -0700

I am drawing lines using mouse event functions,but my main goal is to select those drawn lines and resize or move to another location.how am i supposed to do that?

how to select line or rectangle which is drawn using mouse event dynamically?
how to move selected primitive to another location?
how to re size the line by dragging the selected vertex?

macosx problems with device input

emacinnes — Tue, 08 May 2012 23:06:41 -0700

Device input is non-functional on MacOSX (Snow Leopard 10.6.8, mono 2.10.9) in the latest binary download of OpenTK, as well as version 1.0.278.44921. This includes Mouse input as well as Keyboard input, however with slight differences between the two. Mouse input is simply not recognised, whereas any keyboard input causes a hang (the spinning rainbow cursor). No error messages are received on the command line.

This is true of custom applications, as well as the OpenTK Examples.exe binary that is included.

EDIT; Note that this relates to the gamewindow.mouse and gamewindow.keyboard event overloads to detect device states. As per a previous post on this issue, I moved the device input to use the deprecated InputDevice structure, which results in the same issues. The mouse cursor values are also not updated.

EDIT2: The same code works fine in Windows and Linux with device inputs. After taking the OpenTK code and stepping through it, there's something really bizarre going on internally:
Mouse:

matrix3

joe — Tue, 08 May 2012 14:18:02 -0700

I created a matrix3 class, more or less a copy of the Matrix4 class, but not everything is implemented (Determinant/Invert is missing). You can find a diff at:
http://anthila.dyndns.org/opentk-matrix3.patch

If you want, you can include the code in opentk.

Using GTK# and OpenTK

TheCurseOfNor — Thu, 03 May 2012 07:38:20 -0700

Hello, I'm looking to use GTK# and GtkGLArea# with OpenTK.
Anyone have any idea how would I go about setting up a GTK# window with OpenGL rendered with OpenTK?
Is there a tutorial on that anywhere?

OpenVG Proposal

Max Kosenko — Tue, 14 Jul 2009 03:45:06 -0700

Hello all.

I know that it's planned to support OpenVG later in future. And that's ok.
But before that is done I'd like to propose some thoughts and ideas.

OpenVG 1.1 is nice open standard for 2D rendering engine.
It's main target mobile devices, but it's also declared for engine for device independent UI framework.

One of such framework is Flash and that's even declared in OpenVG 1.1.

But since we are all in .NET world - we have another alternative - XAML based UIs - WPF and Silverlight. WPF and Silverlight don't need any new frameworks, since Microsoft doing that by themselves, but Mono needs new modern UI Framework. GTK# is nice, Windows.Forms also. But all those are really old enough. It's hard to compare them with Silverlight/WPF UI stack.

WPF for Mono stuck somewhere behind just because it's too large project. But Moonlight is well in very active development. Moonlight main target to do Linux support for Silverlight, but we all know that after all difference in Silverlight and WPF not that large. And with Moonlight that becomes possible to make WPF-Like applications based on full Mono framework access.

Per pixel lighting?

.-_ — Sat, 14 Apr 2012 16:36:06 -0700

I am trying to achieve per pixel lighting in my game. When I run my game, everything shows up solid black.

My VS:

varying vec2 texture_coordinate;
 
void main()
{
  vec3 normal, lightDir;
  vec4 diffuse;
  float NdotL;
 
  // Positions
  gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
  texture_coordinate = vec2(gl_MultiTexCoord0);
 
  // Normals
  normal = normalize(gl_NormalMatrix * gl_Normal);
  lightDir = normalize(vec3(gl_LightSource[0].position));
  NdotL = max(dot(normal, lightDir), 0.0);
 
  // Colors
  diffuse = gl_FrontMaterial.diffuse * gl_LightSource[0].diffuse;
  gl_FrontColor = NdotL * diffuse;
}

My FS:

varying vec2 texture_coordinate;
 
uniform sampler2D color_texture;
 
void main()
{
    gl_FragColor = texture2D(color_texture, texture_coordinate) * gl_Color;
}

I don't really know how to set gl_LightSource[0], I set them parameters on light source 0, and enable it.
Any help?

QuickFont

james_lohr — Sun, 31 Jul 2011 16:21:33 -0700

I'd just like to announce the release of QuickFont, a text printing and font generation library: http://www.opentk.com/project/QuickFont

I could only upload 4 images on the project page, so I've uploaded the remaining screenshots here.

Enjoy. :)

James L.