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    • By lxjk
      Hi guys,
      There are many ways to do light culling in tile-based shading. I've been playing with this idea for a while, and just want to throw it out there.
      Because tile frustums are general small compared to light radius, I tried using cone test to reduce false positives introduced by commonly used sphere-frustum test.
      On top of that, I use distance to camera rather than depth for near/far test (aka. sliced by spheres).
      This method can be naturally extended to clustered light culling as well.
      The following image shows the general ideas

       
      Performance-wise I get around 15% improvement over sphere-frustum test. You can also see how a single light performs as the following: from left to right (1) standard rendering of a point light; then tiles passed the test of (2) sphere-frustum test; (3) cone test; (4) spherical-sliced cone test
       

       
      I put the details in my blog post (https://lxjk.github.io/2018/03/25/Improve-Tile-based-Light-Culling-with-Spherical-sliced-Cone.html), GLSL source code included!
       
      Eric
    • By Fadey Duh
      Good evening everyone!

      I was wondering if there is something equivalent of  GL_NV_blend_equation_advanced for AMD?
      Basically I'm trying to find more compatible version of it.

      Thank you!
    • By Jens Eckervogt
      Hello guys, 
       
      Please tell me! 
      How do I know? Why does wavefront not show for me?
      I already checked I have non errors yet.
      using OpenTK; using System.Collections.Generic; using System.IO; using System.Text; namespace Tutorial_08.net.sourceskyboxer { public class WaveFrontLoader { private static List<Vector3> inPositions; private static List<Vector2> inTexcoords; private static List<Vector3> inNormals; private static List<float> positions; private static List<float> texcoords; private static List<int> indices; public static RawModel LoadObjModel(string filename, Loader loader) { inPositions = new List<Vector3>(); inTexcoords = new List<Vector2>(); inNormals = new List<Vector3>(); positions = new List<float>(); texcoords = new List<float>(); indices = new List<int>(); int nextIdx = 0; using (var reader = new StreamReader(File.Open("Contents/" + filename + ".obj", FileMode.Open), Encoding.UTF8)) { string line = reader.ReadLine(); int i = reader.Read(); while (true) { string[] currentLine = line.Split(); if (currentLine[0] == "v") { Vector3 pos = new Vector3(float.Parse(currentLine[1]), float.Parse(currentLine[2]), float.Parse(currentLine[3])); inPositions.Add(pos); if (currentLine[1] == "t") { Vector2 tex = new Vector2(float.Parse(currentLine[1]), float.Parse(currentLine[2])); inTexcoords.Add(tex); } if (currentLine[1] == "n") { Vector3 nom = new Vector3(float.Parse(currentLine[1]), float.Parse(currentLine[2]), float.Parse(currentLine[3])); inNormals.Add(nom); } } if (currentLine[0] == "f") { Vector3 pos = inPositions[0]; positions.Add(pos.X); positions.Add(pos.Y); positions.Add(pos.Z); Vector2 tc = inTexcoords[0]; texcoords.Add(tc.X); texcoords.Add(tc.Y); indices.Add(nextIdx); ++nextIdx; } reader.Close(); return loader.loadToVAO(positions.ToArray(), texcoords.ToArray(), indices.ToArray()); } } } } } And It have tried other method but it can't show for me.  I am mad now. Because any OpenTK developers won't help me.
      Please help me how do I fix.

      And my download (mega.nz) should it is original but I tried no success...
      - Add blend source and png file here I have tried tried,.....  
       
      PS: Why is our community not active? I wait very longer. Stop to lie me!
      Thanks !
    • By codelyoko373
      I wasn't sure if this would be the right place for a topic like this so sorry if it isn't.
      I'm currently working on a project for Uni using FreeGLUT to make a simple solar system simulation. I've got to the point where I've implemented all the planets and have used a Scene Graph to link them all together. The issue I'm having with now though is basically the planets and moons orbit correctly at their own orbit speeds.
      I'm not really experienced with using matrices for stuff like this so It's likely why I can't figure out how exactly to get it working. This is where I'm applying the transformation matrices, as well as pushing and popping them. This is within the Render function that every planet including the sun and moons will have and run.
      if (tag != "Sun") { glRotatef(orbitAngle, orbitRotation.X, orbitRotation.Y, orbitRotation.Z); } glPushMatrix(); glTranslatef(position.X, position.Y, position.Z); glRotatef(rotationAngle, rotation.X, rotation.Y, rotation.Z); glScalef(scale.X, scale.Y, scale.Z); glDrawElements(GL_TRIANGLES, mesh->indiceCount, GL_UNSIGNED_SHORT, mesh->indices); if (tag != "Sun") { glPopMatrix(); } The "If(tag != "Sun")" parts are my attempts are getting the planets to orbit correctly though it likely isn't the way I'm meant to be doing it. So I was wondering if someone would be able to help me? As I really don't have an idea on what I would do to get it working. Using the if statement is truthfully the closest I've got to it working but there are still weird effects like the planets orbiting faster then they should depending on the number of planets actually be updated/rendered.
    • By Jens Eckervogt
      Hello everyone, 
      I have problem with texture
      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();
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OpenGL Which per-frame operations are expensive in terms of performance in OpenGL?

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Ok guys, I already made the camera and hero movement and I loaded one small map consisting of 100 cubes for my mmorpg. I made some ugly models using blender, and I made a function that reads the vertices from .obj file and stores everything in GLfloat array. The next very important thing I need to know is: What kinds of operations should I try to keep to a minimum in my game?
What I gathered from previous posts is:

 

1. Don't make separate VAO and VBOs for every object, because binding and redefining a thousand VBOs every frame takes time.

2. Don't make too much draw calls because that takes time, too.

3. Calculate projection*view*model matrix outside the vertex shader, so you don't calculate the same stuff over and over.

4. Use spheres for collision whenever you can, because it's the simplest possible bounding object.

 

If anything more comes to mind, write it here, please, even if it's not so beginner-friendly, because I can return to this post at some point in the future.

 

And one more thing: I have a question about that 1st principle I just mentioned. Now that I have 7 or 8 models, what I need is a good, logical, performance-wise way of storing them in memory and drawing them on screen. How should I know when is the right time to make another VAO or VBO. Basically I know that VAO is a list of attributes for a number of objects, and it consists of several VBOs, and one VBO can contain vertex coordinates or textures or normals or stuff like that. So, for example, if I have 7-8 models with their own vertex coordinates, should I keep all their vertex coordinates in only one VBO or should I do something else?

Edited by Heelp

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You are asking a problem that may not be necessary for many years to come for you. A lot of people ask this and I tell everyone, optimize when you need to. Hardware is extremely fast nowadays that this shouldn't be a concern. Focus on your game if that is what you are building. If you just want to build the best tech in the world, then that is a different story.

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This kind of thing is actually micro-optimizing with the kind of workload you're doing.

 

The worst operations for performance are and always will be: (1) reading anything back from the GPU, and (2) updating a resource that's in use.  Avoid those, and so long as the rest of your code isn't fighting the API you'll do OK.

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I'm directx not opengl but my understanding in regards to playing nice with the API they are similar.

 

1. Don't draw what you don't need to.  So frustum and if possible occlusion culling.

2. draw front to back to take advantage of hi-z and early-z.

3. sort by state to reduce state changes between draw calls and use texture atlus's to furture reduce state changes.

4. I agree with your 1,2, and 3 except I would say only make as draw calls as you need to and minimize draw calls using various techniques like instancing.

5. mhagain advice is good as well.

6. figure out the best way to upload uniforms to the gpu. (I remember a couple of threads in this forum where there were performance implications)

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1. Don't make separate VAO and VBOs for every object, because binding and redefining a thousand VBOs every frame takes time.
2. Don't make too much draw calls because that takes time, too.
3. Calculate projection*view*model matrix outside the vertex shader, so you don't calculate the same stuff over and over.

1. Yes, if you've got different VBO's per object, you'll have to make extra GL function calls to rebind VBO's inbetween rendering each object. Whether or not this is a problem depends on your game. If you're trying to draw 10's of thousands of unique objects, it's probably an issue. If you're trying to draw one thousand, not as much.

2. Basically, any GL function takes up CPU time. If you design your renderer so that you'll make the least GL calls, then you'll save CPU time. However, in order to do this, sometimes you have to do things that are inefficient for the GPU... Depending on your game, it may be more important to optimize for the CPU or optimize for the GPU.

3. As above, if your game has spare CPU time and is over budget on the GPU, then this could be a good idea. However, if the opposite is true (spare GPU time, over CPU budget), then it may be harmful :P

Also, if you calculate projection*view*model on the CPU, then you need to repeatedly set a uniform value for every single object in the scene. On the other hand, if you put projection*view in one UBO and model in (many) others, then you only need to set projection*view once per frame instead of once per object. If your scene is full of static objects (so model doesn't need to be set every frame), this could be a significant reduction in GL calls...

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1. Yes, if you've got different VBO's per object, you'll have to make extra GL function calls to rebind VBO's inbetween rendering each object. Whether or not this is a problem depends on your game. If you're trying to draw 10's of thousands of unique objects, it's probably an issue. If you're trying to draw one thousand, not as much.
2. Basically, any GL function takes up CPU time. If you design your renderer so that you'll make the least GL calls, then you'll save CPU time. However, in order to do this, sometimes you have to do things that are inefficient for the GPU... Depending on your game, it may be more important to optimize for the CPU or optimize for the GPU.
3. As above, if your game has spare CPU time and is over budget on the GPU, then this could be a good idea. However, if the opposite is true (spare GPU time, over CPU budget), then it may be harmful :P
Also, if you calculate projection*view*model on the CPU, then you need to repeatedly set a uniform value for every single object in the scene. On the other hand, if you put projection*view in one UBO and model in (many) others, then you only need to set projection*view once per frame instead of once per object. If your scene is full of static objects (so model doesn't need to be set every frame), this could be a significant reduction in GL calls...


These are great examples because they also illustrate some other factors to be aware (and beware) of.

 

The main thing that jumps out here is performance vs code complexity vs flexibility.  The example of putting all objects into a single VBO is a great use case for this.  On the one hand you get to reduce VBO binds, but on the other hand your model loading code becomes more complex because you've now got to record offsets for each object (as well as handle the case where a VBO you allocate up-front may not be large enough).  Then you lose the flexibility to load and unload models on the fly.

 

Depending on your program any or all of these may be a deal-breaker.  So don't let the quest for the absolute theoretical highest performance overrule other goals.

 

The example of matrices is another great one, this time illustrating how an optimization in one place can lead to loss of performance in another.  That's often the case with optimizations: you're making a trade-off and hoping that you come out with a net positive.  In this case setting projection * view one-time-only certainly looks attractive, but you end up trading that off against having to make an extra matrix multiplication per-vertex.  That's one of the reasons why we always say "benchmark", because unless you have measurements you'll never know if the work you did to optimize one area didn't come at a greater cost elsewhere.

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Also, if you calculate 

 

projection*view*model on the CPU, then you need to repeatedly set a uniform value for every single object in the scene. On the other hand, if you put projection*viewin one UBO and model in (many) others, then you only need to set projection*view once per frame instead of once per object. If your scene is full of static objects (so model doesn't need to be set every frame), this could be a significant reduction in GL calls...

 

 

Question. Im a stupid person, maybe I don't understand something, but follow my logic here. If I have 2 million vertices, then the vertex shader runs 2 million times. Why would I want to calculate projection*view 2 million times per frame, when I can do it only once per frame in the cpu? What tradeoff??? :blink: 

Edited by Heelp

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Question. Im a stupid person, maybe I don't understand something, but follow my logic here. If I have 2 million vertices, then the vertex shader runs 2 million times. Why would I want to calculate projection*view 2 million times per frame, when I can do it only once per frame in the cpu? What tradeoff??? :blink: 

 

 

 

Also, if you calculate projection*view*model on the CPU, then you need to repeatedly set a uniform value for every single object in the scene. On the other hand, if you put projection*view in one UBO and model in (many) others, then you only need to set projection*view once per frame instead of once per object. If your scene is full of static objects (so model doesn't need to be set every frame), this could be a significant reduction in GL calls...

 

He explains it with the above.

Also GPU's are ALU heavy and they can tear through calculations.

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Why do I need to repeatedly set a uniform value, uniform value is only set up once, and it works for all the vertices, that's why I had declared it to be uniform in the first place.

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