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Questions tagged [opengl]

OpenGL (Open Graphics Library) is a graphics standard and API which is platform-independent and available for desktop, workstation and mobile devices. It is designed to provide hardware-accelerated rendering, and hence gives greatly improved performance over traditional software rendering. OpenGL is used for applications like CAD software and computer games. The OpenGL standard, as well as OpenGL ES, is controlled by the Khronos group.

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35 views

How to scale down noise frequency?

I'm making a space game and so far what I have is a system to generate spheres with noise on them, making them planets. I make a sphere, create noise data, write that data to an image file, and then ...
163 views

Raytracing in OpenGL or Vulkan?

I was looking at this glass ball rendering with an image inside of it (zoom out to see the glass ball), and noticed that it looks like they simulate the refraction of light as it crosses from inside ...
46 views

calculate Gouraud shaded normals after tessellation

I have a triangulated geometry where the vertices are modified by a 3D Perlin noise + Curved-PN triagles algorithm within the Tessellation Evaluation Shader. How can I calculate the normals for the ...
1 vote
370 views

PNG textures render correctly in Blender, but not in OpenGL program

I've been following the OpenGL tutorials from ThinMatrix and I've been able to load and render his stall.obj model along with his stall.png texture just fine. But when I try with my own models and ...
25 views

My projection matrix for OpenGL fails on non-symmetric boundaries

Assuming my viewing volume has x coordinates varies from l to r, and y varies from top to bottom, and finally z-axis varies n to f, I derived the following projection matrix: ...
52 views

How is the alpha value treated when blending?

I'm struggling with understanding how blending works. Here's what I understand: when I set the following ...
1 vote
86 views

After defining an attribute pointer, why can't I just reuse it? I have a VAO bound so shouldn't it just accept the AttributePointer I defined with the last VAO? ...
84 views

Can I copy one texture to another perfectly with texelFetch()

Imagine I have two uncompressed, 2D textures A and B with identical sizes and formats. I bind A to texture unit 0, and B to a framebuffer object. If I draw a full-size polygon in that framebuffer with ...
73 views

OpenGL compute for sizes that aren't a multiple of "local_size"

I've been going round in circles trying to understand OpenGL compute shader "work groups" and it's doing my head in. It's all about as clear as mud. In my compute program I have to set a ...
70 views

OpenGL compute local size vs. performance

Does anybody know if using very small local sizes in compute shaders will hurt performance? eg. If I do this in a shader: ...
30 views

Given 2d control points, how to write a vertex shader that evaluates a cubic bezier curve?

I need to write a program that evaluates a cubic bezier curve, using threejs and vertex shader. I tried to calculate the bezier curve based on the x axis and the control points using the cubic bezier ...
32 views

Why do I get a black scene in OpenGL in Python?

I'm building a scene: a cylinder, and a torus and an icosahedron spin around it, enter the fog and exit the fog. Using a file with a fog texture (any). However, I get a black scene at the exit - why ...
45 views

Intel UHD extremely slow copy operations

Is there a way to make copy operations such as CopyResurce(d3d11) and glBlitFramebuffer(ogl) on multi-sample resources faster ...
1 vote
412 views

Efficiently transferring only needed parts of the vertex data to the GPU (C++/OpenGL)

I have a situation, where I have an array of vertices on the CPU side, for which, besides rendering-relevant data, like their position, I have a lot of other data at each vertex. All vertex data is ...
43 views

Why can't I get fog on OpenGL?

I am creating a cylinder, and there is fog around it. I can't handle two things: the inner surface of the cylinder, realized as a smaller diameter cylinder, actually gives me just a second cylinder ...
1 vote
169 views

Having trouble rendering entire sphere

I'm working on a program where I need to draw spheres. The method I'm using is creating an octahedron And using tessellation shaders to subdivide it into a sphere, however there is a patch of the ...
244 views

OpenGL blending with the screen

I don't understand how OpenGL performs the blending of a texture on the screen. By default, the clear color is set to (0, 0, 0, 0). If we use the default blending equation GL_SRC_ALPHA and ...
57 views

Do GL compute shaders trigger TDR if they crash. Not just timeout?

I'm getting a TDR trigger after 4ms with a GL4.3 compute shader. tdrDelay is currently set to 30 secs, this obviously isn't long enough to get a timeout with the default Windows 11 tdrDelay value let ...
41 views

Optimal Command Ordering for CPU/GPU concurrency

I am writing a renderer that uses a deferred clustered shading technique. On the CPU I group lights, decals, and environment maps into 3 seperate clustered structures (functionally, arrays of unsigned ...
1 vote
868 views

How Skia uses OpenGL backend?

Skia 2D's one notable backend in OpenGL, but how does it work under the hood to render? Say, we need to draw an anti-aliased circle. Does Skia: make a quad (using 2 triangles) and paint the circle ...
1 vote
22 views

How to get back project point cloud from rendered rgbd images by rgbd?

Given a sequence of RGB-D images rendered by blender and the camera parameters for the blender camera(Perspective Projection camera). How can I back project the RGB images with depth map to a RGB ...
71 views

How to properly create textures using DSA for ImageTexture in OpenGL

For the old approach, generating a texture for the ImageTexture for compute shaders would look like this: ...
98 views

Keep constant number of visible circles in 3D animation

I have created a 3D animation with a perspective projection of white circles moving randomly in a fake 3D space projected on a 2D computer screen (GIF 1). Since I need to keep the same number of ...
49 views

OpenGL get default depthbuffer

I have an application that uses only the default opengl framebuffer. It is initialized with color and depth buffer. I want to use the depth buffer as a uniform within a shader to access the current ...
1 vote
50 views

How does changes in vertex data work?

I have been learning computer graphics and for some time and can't seem to wrap my head around one concept. How to handle vertex data changes? Ex. 1. I have a text rendering on a screen. And up on ...
129 views

How does Unreal Engine 5's Lumen (most likely) implement reflections?

In this YouTube video, the creator mentions that reflections in Unreal Engine 5's Lumen "work by tracing the path of light as it bounces off of surfaces in the game world." Does this mean ...
91 views

Point a normal vector towards a point in 3D-Space

Given a normal vector in 3D-Space, how can I rotate the vector, such it points to a point in 3D-Space. I tried couple of ways doing this, which ended up looking completely wrong.
27 views

OpenGL 3.0 is not supported by the OpenGL driver - RizomUV

I have a problem with RizomUV 2022.0. When the program starts, it comes up with pop-up "OpenGL 3.0 is not supported by the OpenGL driver", so I can't import any geometry and work. I'm ...
23 views

What happens when we select lower resolutions on a high-resolution monitor?

I have a monitor with a resolution of 1360x768 (16:9), When I set the resolution to 1280x768 (5:3), 1024x768 (4:3), 800x600 (4:3), even 1920x1080 (16:9) it completely covers the screen and the monitor ...
49 views

Does OpenGL allocate on glBegin/glEnd?

You can enclose arbitrary amount of vertices within glBegin/glEnd statements. Does OpenGL limit the number of vertices you create or it allocates memory for more?
1 vote
186 views

Which coding strategies exist to handle opengl texture size limit?

I recently hit the roof for maximum texture size for my opengl implementation (GL_MAX_TEXTURE_SIZE contains $3379$) when I wanted to create a texture for a 4k resolution video frame ($3840 \times 2160$...
1 vote
33 views

Query the size of an array of non-basic types using interface query in OpenGL

Consider the following code in an OpenGL shader: ...
1 vote
299 views

Problem using Decaling with Stencil to avoid Z-fighting

I need to create a decaling into a surface like a mesh, and to avoid Z-fighting I've been using Stencil Buffer to Turn-off depth test and make the decaling over the surface the Stencil Op permits. In ...
32 views

Opengl binding different mipmap levels of same texture2darray for use in compute shader. How to handle variable nr of levels?

So I want to make a compute shader that uses a coarse-to-fine approach. As I have learned about open gl mipmap levels it seems they could be very useful. However the only binding method which I have ...
38 views

I built a gltf-viewer on my own, but the functionality for loading glf was implemented by referencing gltf-viewer-tutorial, the result is not correct. Below is my ouput for ToyCar.gltf . The ouput of ...
143 views

How do I view my vertex colors that I specified through the texture I've applied on my objec [OpenGL]?

I thought that if I used an image with a transparent background, I would still be able to see the colors I had specified in my vertex attribute buffer. ...
1 vote
81 views

How can I test my GLSL code on different hardware?

I've written a game engine in OpenGL and developed it on my computer with an NVidia GTX 1060. I'm now ready to start releasing it into the wild but I'm worried about hardware issues. I compile my ...
404 views

Unity: Pass texture pointer from OpenGL to Unity

I'm working on a scene in Unity where I have textures loaded at runtime. As a result of that, the scene is being slowed down (even with co-routines), so I thought maybe I could move the texture ...
1 vote
49 views

convert right handed matrix into left handed forward/up/right vectors

I have an openGL style matrix (column major, right handed ) that needs to be converted into two vectors (forward and up) I've managed to find, in a weird way, a solution that matches the the ...
1 vote
228 views

How to instanced and indirect render geometry [OpenGL]

I've a lots of objects, which have the same geometry. Right now I am using instanced rendering to render these objects. This is working very well. But I am trying to increase the performance of the ...
497 views

OpenGL state management

I am working on a software with lots of different shaders, which require different states in OpenGL. My problem is the following: The different models with different shaders are not rendered in the ...
37 views

Best practice for per-vertex updates for mass-spring simulation?

I am new to graphics and physics simulation. I am trying to perform a mass-spring simulation on CPU on individual vertices inside a mesh, and wondering how to best handle this. If working with a rigid ...
113 views

GLFW: create embeddable opengl child window and set parent on Mac?

Is this possible with GLFW? AFAIK you can't use GLFW to create a child window per se, so the question probably boils down on how to turn a GLFW created, opengl enabled window into a child window and ...
31 views

Where does the OpenGL driver get the glGet values from?

I know that the OpenGL driver is implemented by hardware vendors, so this questions may not have a consistent answer. If I use one of the glGet methods, does OpenGL get the information from the GPU or ...
1 vote
58 views

GLSL trying to bind two different layers from the same texture array as images. Should it work and if so what am I doing wrong?

I am new at this particular site in the SE ecosystem, but not to computer graphics in general. If I'm in the wrong spot feel free to redirect me. My question regards glsl programming and binding two ...
1 vote
100 views

Best way for rendering Voronoi diagram from Delaunay graph mesh

I have a set of points, which I triangulate to a Delaunay graph to make a mesh. Every mesh vertex has a unique colour, and I can render it without any problem. But I want Voronoi rendering to be ...
27 views

Why shouldn't I discard faces during Tessellation control stage

In the discussion Here there was said, that discarding faces during Tessellation stage should be avoided. What are the reasons for that? Right now, I am rendering a 3D geometry using Vertex, ...
1 vote
40 views

Why does my uniform only update once?

I have a work thread function which updates the value of a float called scale: ...