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 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 ...
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Animation issue using BVH data in OpenGL
I’m currently working on a project involving animation programming using OpenGL and BVH (Biovision Hierarchy) data for animation, and I am trying to get my head around it. I’ve run into some issues ...
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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 ...
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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:
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How to correctly handle rendering of ~600000, arbitrary colored 2D squares with WebGL?
Information
I have to render a map, that is rendered as a 2d collection of squares of different color, separated by white lines horizontally and vertically. There may be ~600000 squares surrounded by ...
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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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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 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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Why does my implementation of a sinusoidally time-varying color work so slowly?
I've been following TheCherno's OpenGL tutorials and I got to the point where I could render a square by using an index buffer. Now I wanted to vary the color of the square by using $$\frac{\sin(t) + ...
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How to implement camera translation arround object using gluLookAt?
I'm trying to move my camera around the object, a house, using some keyboard keys and the gluLookAt() function.
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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 ...
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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 ...
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How are multisample samples partitioned in OpenGL, and at which points does interpolation take place?
As I understand it, with glEnable(GL_MULTISAMPLE), glEnable(GL_SAMPLE_SHADING) and ...
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Are stencil buffer dimensions required to match render target dimensions?
I may not need as precise pixel-perfect stenciling as my render target during stencil tested render pass. I could be okay with stencil test happening at half or quarter of resolution to save bandwidth,...
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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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Is it possible to fill in Stencil Buffer programmatically via fragment shader?
I've never worked with stencil buffers, but I'm researching if it is the right tool for my task.
Basically I don't understand yet if stencil buffer can only be filled in by some hardcoded rules during ...
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How do double-buffers work in opengl?
As I understand, the back-buffer is used for rendering the image while the front-buffer is drawn on the screen. So if you have only one image to be drawn on the screen, then you only need to swap the ...
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Confusion about glVertexAttribPointer and non-active attributes
When binding an attribute index using glVertexAttribPointer, what happens when a later bound program does not contain an attribute at said index?
Is the behaviour undefined, or is the attribute ...
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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 ...
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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 ...
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Vertex attribute alignment <4 bytes
I know that vertex attributes sourced from vertex buffers in OpenGL need to adhere to the basic alignment requirements of their base types, so e.g. 4 bytes for floats or uints. However, I am unable to ...
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interpolated normal vectors after tessellation. How to hash patch corner / edge vertices?
I have a 3D geometry (an asteroid) that is to be tessellated with respect to the camera position. Each vertex in the original mesh has a unique position and is stored once (VBO with IBO)
In the ...
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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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Is MultiDrawElementsBaseVertex bound by index type?
With glMultiDrawElementsBaseVertex it becomes possible to render multiple sets of indices in one draw call. When using for instance ...
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Tessellation evaluation shader: vertex duplicates on triangle tessellation
I was very surprised when I ran my tessellation evaluation shader, which only counts the number of vertices through an atomicAdd command.
for the following tessellation levels:
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OpenGL texture unit bindings - Why is a single texture mapped to both texture units when each are individually assigned?
I am using NVIDIA Nsight to debug my OpenGL state. In the screenshots below:
I generate a single texture with the ID 10.
I activate ...
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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 ...
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Find good gl_TessLevel for edge distance and edge length
I have a triangular mesh that is read from an ".obj" file and is to be tessellated with respect to the camera position.
I try to avoid T-junctions by tessellating common edges with the same ...
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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 ...
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Loading Gltf model pbr texture produces insane results
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 ...
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is there an universal way to set a uniform?
so I'm working on a game engine.
It's partially python and c++.
One part that is currently a pain point is setting the uniforms for shaders.
Currently I have to define a behavior for all 50+ methods ...
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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 ...
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Is glDeleteBuffers/glGenBuffers needed if I want to resize the buffer?
Firstly the VBO was initialized like below:
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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 ...
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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:
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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
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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 ...
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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 ...
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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:
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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