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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OpenGL ignores glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

I'm learning OpenGL for a personal project. I need to draw a triangle mesh as a wireframe. From what I've read, I can do this using glPolygonMode. However, the program always draws my polygons filled. ...
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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. ...
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Opengl GLSL binding locations confusion

The background of this question is that I am trying to write an automatic binding system, where for each uniform variable I want to declare in my GLSL code, I call a method ...
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Should I learn graphics rendering from scratch or it is ok to go for graphics API? [closed]

I'd like to transition from software engineering to graphics programming, so in the past few weeks I've been creating a path to follow and studying 3D math. My next step is to go for graphics APIs ...
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Precision problems when rendering whole planets

I'm trying to implement a camera, which is able to go very close to a planet/moon surface, without flickering surface. The problem: Right now the position of a planet / moon is saved at the center of ...
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vulkan perspective matrix vs opengl perspective matrix

Hi I have a slight confusion in using the opengl perspective matrix in vulkan. glm's perspective matrix works directly in vulkan just by multiplying the "[1,1 term by -1 but when I compared the ...
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OpenGL in CodeBlocks with GNU GCC compiler not recognising some constants

I am writing basic code to; draw triangles, lines etc; to translate and orient them, and to project them in perspective, solving the occlusion problem using the depth buffer. Having had success with a ...
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OpenGL: read texture mipmap level 0 and render to same texture mipmap level 1

I am trying to generate mipmaps, which are based on depthbuffer values. To generate the next mipmap level, I am trying to read in the 4 pixels of the upper mipmap level per pixel. Unlike the usual ...
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Question about using glVertexAttribArray

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? ...
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split Depthbuffer values to distance

My scenario is a Solar system with satellites. Therefor objects can be very close to the camera while a planet for example is in background far away. This setup causes problems with the depthbuffer ...
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How to use maximum resolution (pixel density) with OpenGL in MS Windows

CodeBlocks offers an example program in C, that uses OpenGL. It draws a single multicoloured rotating triangle. I have been building on this example. I am a novice in C and in OpenGL. I believe that I ...
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SSAO with reconstructed depths yields strip artifacts

I wrote an ssao algorithm with compute shaders and view-position-reconstruction from the depth buffer. It works great for objects near by but results in strip or banding artifacts for large planes ...
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If a GPU supports OpenGL ES 3.2, does it also support OpenGl 3.0?

At the moment I am looking for a tablet to use the bike simulator app "BKOOL". The Samsung Galaxy Tab S6 Lite is my current favorite and it meets almost all app requirements (https://www....
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Renderdoc reports incorrect OpenGL API usage, can't figure out why

I'm rendering some UI using an immediate-mode UI library, so each frame it produces some meshes, which I then load into buffers and render, only to get some strange errors from Renderdoc: You can see ...
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How to Achieve Radial Rendering

I'm making a POV fan and would like to display some simple graphics in real-time on it. I have a working naive solution with OpenGL, but I'm maxing out at 7 fps rending a simple cube on a raspberry pi ...
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How to render fog in OpenGL

I have a simple question just because I can’t find any good example in the internet. How to create fog without using particles? How to make for with different density on different locations and in ...
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"Interleaved rendering" in fragment shader

Intro I'm trying to render multi-channel images (more than 4 channels, for the purposes of feeding it to a Neural Network). Since OpenGL doesn't support it natively, I have multiple 4-channel render ...
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1answer
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Trying to understand how to render a volumetric point light

My goal is to render a volumetric point light as explained in this book's chapter 10: FGED Rendering The book explains the math pretty well, but I'm not sure I understand what is the required setup ...
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130 views

Compute Shader shared average value

Short Question: How can i integrate a buffer variable in a compute shader over each pixel i.e. how can i ensure memory coherence in such a case? Long Question: I've written a deferred renderer with ...
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How OpenGL handles assigning the same state multiple times in a row

I wonder what happens when functions that change OpenGL states, ex glBindVertexArray or glBindTexture are called with the same ...
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Passing non-interleaved data to glBufferStorage without using glBufferSubData

I would like to use glBufferStorage to load data once into the vertex buffer. However sometimes I want to pass non-interleaved data from separate arrays like shown ...
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1answer
146 views

OpenGL transparency - object behind is not rendered

I'm trying to implement voxel world using OpenGL (Core 3.3). I've come across a problem with transparency. It looks like sometimes GPU decides to not render stuff that would be important. Can you help ...
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glsl passing data array from vertex to tessellation control shader

I am trying to pass a vec3 array from vertex shader to tessellation shader. passing just one value works fine, but how to pass an array? Vertex shader ...
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1answer
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optional geometry shader

I am looking for an easy solution for passing information between shader stages when adding additional shader stages. Right now I am using the "out" keyword to pass data from for example ...
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1answer
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Stripping unnecessary data from C++ data structures before sending to GPU

I've recently been working on a particle system in my renderer and I've encountered a situation where my particle class on the C++ side has data I need to maintain my particle on that end, but that I ...
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1answer
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Mesh-Shader and layered rendering

In the usual pipeline (vertex, tessellation, geometry and fragment shaders) the geometry can be deformed and in the geometry shader it is possible to copy the generated and deformed geometry in order ...
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Is BSP the right tool for my game?

I am brushing up on the fundamentals of OpenGL. Things are going great. I am looking at BSP for maps/levels. I understand that Doom uses BSP, but I worry. Can BSP be used with complete 3D world and ...
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What is the Viewport?

Can someone please explain to me what the Viewport is. I've read the OpenGL wiki and doc.gl but they give me a definition that I don't understand at all. The definition they gave me is "...
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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 ...
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opengl and glxinfo

I have a question about reading glxinfo. I'm running a Fedora 31 virtual machine. When I look at glxinfo (using softpipe) with this command: ...
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1answer
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Unexpected INVALID_OPERATION on glClearNamedBufferData

Under OpenGL 4.5 on AMD RENOIR (DRM 3.40.0, 5.10.56-1-lts, LLVM 12.0.1), running ...
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openGL plotting point to window not using glutDisplayFunc(your_func)

I want to plot complex data points to a window to display. I know how to do it all in one go: ...
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1answer
76 views

Opengl geometry shader input point to output point doesn't show any ouput

I am trying a simple passthrough just to get a feel for the geometry shader. I am taking in a single point and trying to output that point from the geometry shader, it works with the vertex and ...
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Dark line artifact along edges of the shaded mesh

I have implemented an algorithm to calculate vertex normals by taking the normalized average of all its adjacent triangles. I have subdivided a cube two times with catmull clark and checked the ...
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1answer
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OpenGL on mac gives me an error when calling glGenVertexArrays

I have been developing a c++, openg, glfw3 and GLEW project on ubuntu and everything has worked so far. Recently I moved to a mac computer (chip M1 if it's important) and things stopped working. I ...
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OpenGL invalid location when using a literal value in C++, but works when using glGetUniformLocation before

I have a call glUniformMatrix4fv(42, ...other parameters...) with a shader that has layout (location = 42) uniform mat4 someMat; ...
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1answer
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is doing transform feedback while rendering vertices not possible?

I've written a program that uses OpenGL and GLFW to display some simple geometric shapes. I'm now trying to add some transform feedback capability to it and I find that as soon as I do so, the program ...
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1answer
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why is reported screen size smaller than display size with GLFW full screen window

I'm using GLFW to create a full screen GL application. I'm running it on my Ubuntu 20.04 laptop that has a typical 1920:1080 display, at least that's the screen resolution reported under Settings->...
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1answer
62 views

Techniques to implement a glow that encompasses a volume

I have an old renderer from years ago written with OpenGL immediate mode. I've decided to learn Vulkan and I'm converting my old project as a way to learn the new concepts. One of the things my old ...
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How widespread are T-vertex artifacts nowadays?

As far as I know, OpenGL specifies that you cannot rely on precise rounding of vertex and edge coordinates for rasterization - which means that T-vertices may cause small artifacts: a continuous and a ...
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1answer
85 views

Simulate projection matrix deformation in two camera setup

For educational purposes I'm trying to simulate what a scene would look like with a perspective matrix deformation (before everything is brought to NDC) but I'm unsure how to do this. I'd like to do ...
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1answer
86 views

Problem when performing IFFT for Tessendorf's ocean waves

I am implementing Jerry Tessendorf's ocean waves as described in his paper in c++ and OpenGL. I implemented two compute shaders, one for the h_tilde_0 and its conjugate, and one for the frequency ...
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2answers
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Reducing Cascaded Shadow Mapping Artifacts

I've been trying to get my cascaded shadow maps looking right for a while. I managed to fix the shimmering and most of the quantization artifacts, but for some reason the shadows still look really ...
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1answer
63 views

Why are degenerate triangles rasterized when using GL_LINE polygon mode

I have made use of degenerate triangles when rendering a mesh. While the degenerate triangles are not rasterized when using GL_FILL polygon mode, they are when I do ...
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Calculating the intersection of two volumes

What is an efficient way to calculate the volume of intersection of two arbitrary volumes described as closed surfaces? That is, with two meshes, A and B, how do I calculate the intersection of A and ...
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1answer
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how to change the near clipping plane of a perspective projection matrix for OpenGL

I am trying to only change the near clipping plane of a given perspective projection matrix for OpenGL. My problem is, that the near clipping plane is way too close, and the far clipping plane is very ...
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24 views

OpenGL Per-Object Outlining issues

I'm trying to draw onlines around the objects, the outlines for any object should be see though very other object, I've successfully been able to draw the outline but the pixels get discarded in the ...
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1answer
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DirectX FVF(Flexible Vertex Format ) equivalent in OpenGL/Vulkan?

Is there any directX FVF(Flexible Vertex Format ) equivalent in OpenGL/Vulkan.
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List all faces of a mesh visible from the view of the camera Opengl

as the question suggests I have to identify all the faces that are visible from the camera's view and do some processing with them. I have a single mesh. I am thinking of giving individual faces a ...
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1answer
187 views

glBlitFramebuffer does not copy all textures

The setup I have a working bloom shader implemented which creates a fbo with two textures attached to it. The first texture holds the entire scene The other only displays objects which are supposed ...

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