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      Good evening everyone!

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      Hello guys, 
       
      Please tell me! 
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    • By Jens Eckervogt
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      using System; using OpenTK; using OpenTK.Input; using OpenTK.Graphics; using OpenTK.Graphics.OpenGL4; using System.Drawing; using System.Reflection; namespace Tutorial_05 { class Game : GameWindow { private static int WIDTH = 1200; private static int HEIGHT = 720; private static KeyboardState keyState; private int vaoID; private int vboID; private int iboID; private Vector3[] vertices = { new Vector3(-0.5f, 0.5f, 0.0f), // V0 new Vector3(-0.5f, -0.5f, 0.0f), // V1 new Vector3(0.5f, -0.5f, 0.0f), // V2 new Vector3(0.5f, 0.5f, 0.0f) // V3 }; private Vector2[] texcoords = { new Vector2(0, 0), new Vector2(0, 1), new Vector2(1, 1), new Vector2(1, 0) }; private int[] indices = { 0, 1, 3, 3, 1, 2 }; private string vertsrc = @"#version 450 core in vec3 position; in vec2 textureCoords; out vec2 pass_textureCoords; void main(void) { gl_Position = vec4(position, 1.0); pass_textureCoords = textureCoords; }"; private string fragsrc = @"#version 450 core in vec2 pass_textureCoords; out vec4 out_color; uniform sampler2D textureSampler; void main(void) { out_color = texture(textureSampler, pass_textureCoords); }"; private int programID; private int vertexShaderID; private int fragmentShaderID; private int textureID; private Bitmap texsrc; public Game() : base(WIDTH, HEIGHT, GraphicsMode.Default, "Tutorial 05 - Texturing", GameWindowFlags.Default, DisplayDevice.Default, 4, 5, GraphicsContextFlags.Default) { } protected override void OnLoad(EventArgs e) { base.OnLoad(e); CursorVisible = true; GL.GenVertexArrays(1, out vaoID); GL.BindVertexArray(vaoID); GL.GenBuffers(1, out vboID); GL.BindBuffer(BufferTarget.ArrayBuffer, vboID); GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(vertices.Length * Vector3.SizeInBytes), vertices, BufferUsageHint.StaticDraw); GL.GenBuffers(1, out iboID); GL.BindBuffer(BufferTarget.ElementArrayBuffer, iboID); GL.BufferData(BufferTarget.ElementArrayBuffer, (IntPtr)(indices.Length * sizeof(int)), indices, BufferUsageHint.StaticDraw); vertexShaderID = GL.CreateShader(ShaderType.VertexShader); GL.ShaderSource(vertexShaderID, vertsrc); GL.CompileShader(vertexShaderID); fragmentShaderID = GL.CreateShader(ShaderType.FragmentShader); GL.ShaderSource(fragmentShaderID, fragsrc); GL.CompileShader(fragmentShaderID); programID = GL.CreateProgram(); GL.AttachShader(programID, vertexShaderID); GL.AttachShader(programID, fragmentShaderID); GL.LinkProgram(programID); // Loading texture from embedded resource texsrc = new Bitmap(Assembly.GetEntryAssembly().GetManifestResourceStream("Tutorial_05.example.png")); textureID = GL.GenTexture(); GL.BindTexture(TextureTarget.Texture2D, textureID); GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)All.Linear); GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)All.Linear); GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba, texsrc.Width, texsrc.Height, 0, PixelFormat.Bgra, PixelType.UnsignedByte, IntPtr.Zero); System.Drawing.Imaging.BitmapData bitmap_data = texsrc.LockBits(new Rectangle(0, 0, texsrc.Width, texsrc.Height), System.Drawing.Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppRgb); GL.TexSubImage2D(TextureTarget.Texture2D, 0, 0, 0, texsrc.Width, texsrc.Height, PixelFormat.Bgra, PixelType.UnsignedByte, bitmap_data.Scan0); texsrc.UnlockBits(bitmap_data); GL.Enable(EnableCap.Texture2D); GL.BufferData(BufferTarget.TextureBuffer, (IntPtr)(texcoords.Length * Vector2.SizeInBytes), texcoords, BufferUsageHint.StaticDraw); GL.BindAttribLocation(programID, 0, "position"); GL.BindAttribLocation(programID, 1, "textureCoords"); } protected override void OnResize(EventArgs e) { base.OnResize(e); GL.Viewport(0, 0, ClientRectangle.Width, ClientRectangle.Height); } protected override void OnUpdateFrame(FrameEventArgs e) { base.OnUpdateFrame(e); keyState = Keyboard.GetState(); if (keyState.IsKeyDown(Key.Escape)) { Exit(); } } protected override void OnRenderFrame(FrameEventArgs e) { base.OnRenderFrame(e); // Prepare for background GL.Clear(ClearBufferMask.ColorBufferBit); GL.ClearColor(Color4.Red); // Draw traingles GL.EnableVertexAttribArray(0); GL.EnableVertexAttribArray(1); GL.BindVertexArray(vaoID); GL.UseProgram(programID); GL.BindBuffer(BufferTarget.ArrayBuffer, vboID); GL.VertexAttribPointer(0, 3, VertexAttribPointerType.Float, false, 0, IntPtr.Zero); GL.ActiveTexture(TextureUnit.Texture0); GL.BindTexture(TextureTarget.Texture3D, textureID); GL.BindBuffer(BufferTarget.ElementArrayBuffer, iboID); GL.DrawElements(BeginMode.Triangles, indices.Length, DrawElementsType.UnsignedInt, 0); GL.DisableVertexAttribArray(0); GL.DisableVertexAttribArray(1); SwapBuffers(); } protected override void OnClosed(EventArgs e) { base.OnClosed(e); GL.DeleteVertexArray(vaoID); GL.DeleteBuffer(vboID); } } } I can not remember where do I add GL.Uniform2();
    • By Jens Eckervogt
      Hello everyone
      For @80bserver8 nice job - I have found Google search. How did you port from Javascript WebGL to C# OpenTK.?
      I have been searched Google but it shows f***ing Unity 3D. I really want know how do I understand I want start with OpenTK But I want know where is porting of Javascript and C#?
       
      Thanks!
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OpenGL Color Key working not the way I expect

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Hi gamedevers, I'm new to game programming and I hope you guys don't mind about my stupid question. I'm really having a hard time trying to figure out how to solve this problem. I hope you can help me. One way to enable color keying in OpenGL is creating an alpha channel on my image. Setting 0 for pixels to be ignored and 1 for colored ones. Then, using blending options. So far so good, pixels to be ignored are just ignored. However, when two colored ones intersect, a new brigther one comes up. That's a behaviour I wouldn't like to happen with my images. Appers to me that DEPTH_TEST is the solution. It turns out I didn't manage to make it work properly. Here's my image (they are brigther where they overlap) Free Image Hosting at www.ImageShack.us<br /><br />QuickPost Quickpost this image to Myspace, Digg, Facebook, and others! Thanks

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What did you set your blending function to?


Also, you said "0 for pixels to be ignored and 1 for colored ones." - do you put them as floats(0.0-1.0) or as integers(0-255)?

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Quote:
Original post by JPerry
Hi gamedevers,

I'm new to game programming and I hope you guys don't mind about my stupid question. I'm really having a hard time trying to figure out how to solve this problem. I hope you can help me.

One way to enable color keying in OpenGL is creating an alpha channel on my image. Setting 0 for pixels to be ignored and 1 for colored ones. Then, using blending options.

So far so good, pixels to be ignored are just ignored. However, when two colored ones intersect, a new brigther one comes up.

That's a behaviour I wouldn't like to happen with my images.

Appers to me that DEPTH_TEST is the solution. It turns out I didn't manage to make it work properly.

Here's my image (they are brigther where they overlap)

Free Image Hosting at www.ImageShack.us<br /><br />QuickPost Quickpost this image to Myspace, Digg, Facebook, and others!

Thanks


Please post your relevant rendering code between [ source ] and [ /source ] tags w/o the spaces so we can get a look at what you are actually doing.

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I assume its cause u have some additive mode enabled
use something else eg GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA

or if its just a colorkey like effect then dont enable blending at all
but use glEnable( GL_ALPHA_TEST );
gALPhaFunc( GL_GREATERm 0.0 )

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someboddy: sorry, I meant 255. They are all integers.

The root of the problem was my TexEnvF. Setting it REPLACE instead of DECAL did the trick. I found a reference on opengl superbible 4th edition.

Quote:
If you want simple replace the color of the underlying geometry, you can specify GL_REPLACE for the environment mode. Making this change eliminates any effect on the texture from the underlying geometry.


I'm now going with only alphatest. I wonder when is alphablend more desirable than alphatest??


Thank you for all your help.

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alphatest only has two results, pass + fail

blending with say GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA

lets u specify how much to blend, thus results generally look a bit nicer (esp around the edges), though its slightly slower than alphatest.

one benifit with alphatest is if the fragment fails, it does get written to the depthbuffer.
blending it does even if the fragement aint visiable

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