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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.
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      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.
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    • 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 Ray generation

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I'm beginning work on a raytracer and I've managed to get the basics up and running but I've started running into some problems with the ray generation. When I setup my camera at (0, 0, -10) looking at (0, 0, 0), with up (0, 1, 0), the ray in the middle of the viewport (512x512) should be (0, 0, 1) right? (pointing straight to the lookat point). Here's my code for creating the matrices:
inline void mat_perspective(matrix44* res, float fov, float aspect, float hither, float yonder)
{
	float invtanf = 1.0f / tanf( fov / 2.0f );
	mat_load(res, 
		invtanf / aspect, 0, 0, 0,
		0, invtanf, 0, 0,
		0, 0, -(yonder + hither) / (hither - yonder), yonder * hither / (hither - yonder),
        0, 0, 1, 0);
}

inline void mat_lookat(matrix44* res, const vec3& Position, const vec3& View, const vec3& Up)
{
	vec3 dir, right, newUp;
	vec_sub(View, Position, &dir);		
	vec_normalize(dir, &dir);
	
	vec_normalize(Up, &right);	
	vec_cross(dir, right, &right);
	
	vec_cross(right, dir, &newUp);

	mat_load(res,
		right.x, newUp.x, dir.x, Position.x,
		right.y, newUp.y, dir.y, Position.y,
        right.z, newUp.z, dir.z, Position.z,
        0, 0, 0, 1.0f);	
}

inline void mat_viewport(matrix44* res, float x, float y, float width, float height)
{
	mat_load(res, 
		(width - x) / 2, 0, 0, (width + x) / 2,
		0, (height - y) / 2, 0, (height + y) / 2,
		0, 0, 1, 0,
		0, 0, 0, 1);
}



And for creating the camera and generating rays:
void cam_perspective(Camera* cam, const vec3& pos, const vec3& view, const vec3& up, 
						float fov, float width, float height, float hither, float yonder)
{
	mat_lookat(&cam->WorldToCamera, pos, view, up);
	mat_perspective(&cam->CameraToScreen, fov, width / height, hither, yonder);
	mat_viewport(&cam->ScreenToRaster, 0, 0, width, height);

	mat_inverse(cam->WorldToCamera, &cam->CameraToWorld);
	mat_inverse(cam->CameraToScreen, &cam->ScreenToCamera);
	mat_inverse(cam->ScreenToRaster, &cam->RasterToScreen);

	mat_mul(cam->RasterToScreen, cam->ScreenToCamera, &cam->RasterToCamera);

	mat_print(cam->RasterToScreen);

	cam->scr_width = width;
	cam->scr_height = height;
	cam->hither = hither;
	cam->yonder = yonder;
}

void cam_generate_ray(const Camera& cam, const Sample& sample, ray3* ray)
{
	vec_load(&ray->o, 0, 0, 0);
	vec_load(&ray->d, sample.imageX, sample.imageY, 0);

	//we need to transform this as a point
	mat_transf_point(cam.RasterToCamera, ray->d, &ray->d);

	vec_normalize(ray->d, &ray->d);
	ray->mint = 0.0f;
	ray->maxt = (cam.yonder - cam.hither) / ray->d.z;

	mat_transf_point(cam.WorldToCamera, ray->o, &ray->o);
	mat_transf_vec(cam.CameraToWorld, ray->d, &ray->d);
}
I know it's quite a bit of code to post, but I've looked in different places and the perspective matrices are given quite differently. For example: 1 | 2 | 3 | 4 I'm using the one OpenGL uses but with 1 in m[3][2] (taken from "Physically based rendering" by Pharr and Humphreys). Another question: i've seen some places use NDCs and some use Cannonical coordinates.. is there any important difference affecting the end result?

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I'm not sure about your code, but here is what I use. Note that I use a left handed coordinate system, while you're using a right handed one (at least I think so, since you're using a OGL matrix format, don't you?)

bool QLCamera::GenerateRay(uint x, uint y, ray &r) const
{
r.Set(viewp[0] + dx*x + sx*cx + dy*y - sy*cy - position, position);
return true;
}
void QLCamera::SetupCamera()
{
vector3 at(position + direction);
vector3 up(0, 1, 0);
vector3 p(position);
ResetCamera();

position = p;
direction = at - position;

matrix m;
m.LookAt(position, at, up);
m.Invert();

m.Apply(viewp[0]);
m.Apply(viewp[1]);
m.Apply(viewp[2]);
m.Apply(viewp[3]);

dx.Set((viewp[1] - viewp[0]) / res_x);
dy.Set((viewp[2] - viewp[0]) / res_y);
sx.Set(dx / samples_x);
sy.Set(dy / samples_y);

diameter = focal / fstop;
ppmx = res_x / cameras[current_camera].w;
ppmy = res_y / cameras[current_camera].h;
}


I don't do the job using matrices. Instead, I use 4 points that rapresent the four viewplane corners, and transform them before I generate the rays. Then I interpolate throught those vertices and generate the rays.
Sorry if that does not answer to your question, but hope it helps.
By the way, is there some reason to use your method instead of mine? Is your faster?

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Given the camera coordinates and lookat point you provided, then yes the center ray should originate at (0, 0, -10) and point in the direction (0, 0, 1) after normalization.

I've always used the same method as cignox1 described - four points provide the viewplane corners (based on desired FOV and aspect ratio) and then the rays for each individual pixel are interpolated from those four corners. Generally in my experience this avoids some pitfalls with weird aspect problems and the occasional camera rotation oddity.

You said you've run into some problems but you didn't give any details about what sort of problems. Are rays being generated incorrectly? Is there an aspect or FOV problem? Is there a strange magnification problem (camera seems too zoomed in/zoomed out)?

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Quote:
Original post by ApochPiQ
You said you've run into some problems but you didn't give any details about what sort of problems. Are rays being generated incorrectly? Is there an aspect or FOV problem? Is there a strange magnification problem (camera seems too zoomed in/zoomed out)?


Yes, the rays are generated incorrectly, in the middle of the viewport I don't get (0, 0, 1), but something close, but off by quite a large angle. I was wondering if my matrices are correct.

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Sounds like it's most likely a calculation problem somewhere. Depending on how close the values are it may even be a floating-point precision issue, but I doubt it if the discrepancy is large enough to be noticeable.

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