Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [opengl]

For questions involving use of the OpenGL graphics library.

0
votes
0answers
14 views

sdl2: Compiler throws “Undefined Reference”

I'm trying to learn computer graphics, but when I tried to get this very simple windower running with c ...
0
votes
0answers
15 views

How to rotate an object in OpenGL on the X, Y and Z axis on its local coordinates?

I've read multiple tutorials, but I still can't understand how do I properly rotate an object in 3D space on all 3 axis at once. For example, I'd like to give the object a pitch of 60 degrees, yaw of ...
0
votes
1answer
19 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 ...
0
votes
0answers
3 views

Linker Error in VS 2017 community with GLAD [migrated]

This code is a direct copy of an example. I have references set, however it appears that GLAD doesn't have a lib file; and I think that is what I am missing. Does anyone know a way around this issue?...
1
vote
1answer
50 views

gl_FragCoord and glViewport

I've been scanning the specifications for both OpenGL and GLSL, and I can't find a definitive answer as to how exactly are gl_FragCoord's ...
0
votes
1answer
26 views

Vulkan: efficient way to update VBO mesh vertices?

I would like to change/add/remove some mesh vertices in existing VBO's (while deforming and remeshing 3D objects) . With OpenGL I would have to reload whole vertex VBO's. I suppose with Vulkan there ...
-1
votes
0answers
49 views

How can I draw a 3D crystal unit cell (NaCl as an example) on OpenGL?

I'm a physics a student and currently working on OpenGl. I have been searching for applications related to physics that could be simulated. I want to write a code for a unit cell of NaCl on Opengl. ...
1
vote
1answer
88 views

How to do CSG on 3D triangulated objects, originally stored as a .obj file, using openGL or other libraries?

What I would like to do is to create a crater on a field. To do so, I thought that creating a universal crater object (something cone-shaped) and then subtracting it from the field on a specified ...
2
votes
1answer
44 views

GL_DEPTH_CLAMP has no effect (reverse z)

In an effort to improve cascaded shadow maps, I have looked into using GL_DEPTH_CLAMP and moving the near and far plane just around the actual view frustum instead of the global bounding box. But the ...
2
votes
1answer
56 views

Why is cos(𝜃) in the denominator in the reflectance equation and in the numerator in the shading equation?

Background: I'm reading https://learnopengl.com/PBR to learn about PBR. In the theory slide (https://learnopengl.com/PBR/Theory), the author has the reflectant equation as The theta (the angle ...
0
votes
1answer
77 views

Sphere Texture Mapping Algorithm

I am trying to generate UV coordinates automatically to map a texture on a sphere. The problem is with seams when going from 0.8 to 0.2 there is a discontinuity and interpolation in fragment shader ...
-1
votes
1answer
50 views

Difficulty including GLM into Visual Studio with OpenGL

I have been trying to implement GLM (math library) into Visual Studio with OpenGL. I have followed and watched many online resources that point me to include only the GLM folder inside the ...
1
vote
0answers
62 views

Convey screenspace bounding box of rendering result

Imagine I render to an FBO some arbitrary geometry. Geometry can be rendered via single or multiple draw calls. For the sake of the question, assume I know nothing about geometry or transformation ...
2
votes
0answers
54 views

Show the edges between the clipping plane and clipped objects [closed]

I want to utilize shaders to not only discard fragments if they are on one side of a predefined plane but also render a contour along the intersection. My fragment shader currently does something ...
-2
votes
1answer
89 views

This function syntax is confusing me

gladLoadGLLoader((GLADloadproc)glfwGetProcAddress) I have never seen this syntax before. Presumably glfGetProcAddres is a function, but it has the brackets behind it. Is this only possible in open gl ...
1
vote
1answer
89 views

GBuffer: Framebuffer with different texture format types?

I rely on this answer from Nathan Reed: How much precision do I need in my G-Buffer? It is proposed to use two different texture formats for one Gbuffer. However as far as I know, color texture ...
1
vote
1answer
69 views

OpenGL Unable to retrieve the values of data sent to shader using textures

I've been following these tutorials and i can't figure out how to send data to shaders using textures. https://en.wikibooks.org/wiki/OpenGL_Programming/Scientific_OpenGL_Tutorial_02 In this tutorial ...
-1
votes
2answers
235 views

How do I use texture coordinates of a .obj file in OpenGL?

I have an obj file, with texture coordinates (indicated by vt). How would I use this to load textures in OpenGL?
1
vote
0answers
70 views

Specular/Diffuse light on an icosahedron opengl

I'm having a problem with my model here. I draw an icosahedron using GLUT, and the radius is set to 0.8. The info of the coordinates are listed below: (X and Z are calculated since our radius is 0.8) ...
1
vote
1answer
50 views

GL_SAMPLE_ALPHA_TO_COVERAGE and depth testing

I am currently looking into alternatives to my current, somewhat slow but exact, OIT approach. Specifically, GL_SAMPLE_ALPHA_TO_COVERAGE to convert the alpha value into a per-sample mask. ...
0
votes
1answer
73 views

Efficiently drawing multiple instances of 3D objects

I was able to write the following working code to draw any number of "sprites" (defined as 2 tringles, 6 vertices) ...
0
votes
1answer
84 views

Convert shader from GLsl 1.50 to 1.30

I'm a newbie with OpenGl and I'm stuck in following the tutorial. I found this tutorial with these shaders ...
0
votes
1answer
87 views

Why is glreadpixels only working in certain cases?

If I try to read the screen with glreadpixels and then draw the same thing again using gldrawpixels it works, BUT if and only if ...
1
vote
1answer
183 views

Is a single shader and 1x1 pixel white sampler more efficient than frequent switching between shaders with and without samplers?

I have some existing OpenGL code that I am porting to Vulkan. The question is somewhat relevant to both OpenGL and Vulkan. I am rendering some primitives using textures, some single channel, others ...
1
vote
1answer
181 views

Translate an arcball camera upwards or left-right

This problem is giving me a really hard time. I'm always looking at the origin and have a camera that moves around it in an arcball mode. That part works beautifully: I'm calculating the camera ...
2
votes
1answer
140 views

Project vertex onto plane

What I have: a plane given by its normal$\ n $ and a point on the plane$\ p $. a 3D-point$\ v $. a direction$\ d$. What I need: the projection of$\ v$ along$\ d$ onto the plane. How can I ...
1
vote
1answer
194 views

Drawing Directed Lines (with arrow endings)

I am working on a simple graph viewer with OpenGL. My problem with is directed edges. I tried to draw arrow endings with GL_TRIANGLES but somehow my calculations are off. I've used direction cosine ...
1
vote
1answer
99 views

Is it possible to access adjacent vertex data in tessellation evaluation shader?

I'm trying to render thick cubic Bezier curves using the whole OpenGL 4.5 pipeline: I render a patch with 4 control points. Vertex shader is simply pass-through to tessellation control shader. ...
2
votes
1answer
87 views

LoopBlinn Cubic Curve Rendering - Serpentine arteffect

I am trying to implement the Loop-Blinn cubic curve in java using the following source codes GPU-Curve-Rendering and WebCore. Both of them are showing few arteffects and i cannot figure out why. Here ...
2
votes
2answers
194 views

How can I draw this style of grid?

I'm trying to write code (in any language) to render this 3D grid, matching the look and colors as closely as possible:
0
votes
1answer
71 views

Adding vbos to a vao once it has been created

Is it possible to add vbos to vbos after their creation? For example (pseudo-code): ...
6
votes
1answer
94 views

Do operating programs such as Microsoft Office or Windows Explorer use OpenGL to draw?

I have a server and my only monitor is plugged into its graphics card. My question is - do all programs (Windows explorer, Excel whatever) draw their output using the graphics card and more ...
0
votes
1answer
112 views

How to include OpenGL extension loader in my project

I have a modern OpenGL project hosted publicly. I want to create the easiest experience so someone can just clone the repo and have it just work. So far, I have included (as git submodules) the ...
2
votes
0answers
52 views

Identification of visible area of a plane in OpenGL

I have somewhat generalized version of this question: https://stackoverflow.com/questions/52475104/how-to-show-visible-part-of-planar-world-rendered-with-3d-perspective-on-topside -‎ I would also like ...
2
votes
2answers
394 views

What's the point of “work groups” for OpenGL compute shaders?

glDispatchCompute has the number of work groups as arguments. What is the point of having work groups? How are they useful, compared to just having NxM independent pixel calculations with a known (x,...
4
votes
1answer
108 views

How to apply wire texture for realistic rendering of embroidery?

I am building an algorithm which takes a bitmap image as input and render the image as an embroidery design. The different steps are : Vectorize the image, I keep only 5 colors (Done) Generate ...
-1
votes
2answers
115 views

Relatively new to OpenGL, need guidance/tips on an assignment with interactive user input

I'm currently taking a Computer Graphics class at university, and have been given an assignment which involves loading an obj file and manipulating it with keyboard and mouse controls (eg. arrow keys ...
3
votes
2answers
260 views

Why are depth buffer values clamped to (0, 1)?

This is a simple question. I know that in OpenGL or other graphics API, the values stored in the depth buffer are automatically clamped to (0,1). I just want to know why people do this instead of ...
1
vote
1answer
48 views

What does “region to be shaded” mean in the PCF paper?

I am reading the percentage closer filtering (PCF) paper by Reeves, W. et al. (https://graphics.pixar.com/library/ShadowMaps/paper.pdf). At at section 3.2, it mentioned that "each shading calculation ...
3
votes
2answers
101 views

Can gl_WorkGroupSize be set outside the compute shader?

I am migrating code from CUDA to OpenGL compute shaders. I could not find a way to set the local workgroup size outside the shader; is there a way to set gl_WorkGroupSize in the calling program like ...
0
votes
1answer
171 views

Multiple VAO share a EBO (OpenGL 3.3)

As mentioned here, multiple VAOs can share a single VBO. However, can multiple VAOs share a single EBO? For example, I want to create 2 rectangles. So, I do the following: ...
1
vote
1answer
118 views

Difference between relativeOffset and offset in VAO with Direct Access Ext

Using The DSA Ext with opengl , API calls to guide opengl to the buffer format are : ...
1
vote
1answer
89 views

Issue with loading a texture on the GPU with OpenGL 4.1 Core profile

I’ve been trying to render a texture on the whole screen in OpenGL 4.1 using the Core profile and followed a few tutorials on the matter, but all I have so far is a blank screen. I tried using my ...
1
vote
0answers
66 views

glTexSubImage3D throws GL_INVALID_ENUMERATION on NVIDIA

I'm having problems when using the following statement on different GPUs: glTexSubImage3D(target, 0, 0, 0, 0, width, height, layers, format, type, NULL); on ...
0
votes
0answers
75 views

How to compute size of OpenGL's image buffer?

I am trying to retrieve OpenGL's color buffer with the following code. My program is crasing in the line that makes the call to glReadPixels() apparently image.data ...
1
vote
0answers
357 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
1answer
72 views

Drawing a plane super-imposing over another plane

I wish to draw a plane (A building's floor in this case) over a canvas plane (assume the plane is smooth). The planes are drawn as QUADS. The problem is that both plane are located at the same height....
0
votes
0answers
82 views

Hard edges appearing in voxel cone tracing (how to remove them?)

I am generating shadows using a voxel pyramid (commonly called voxel cone, although I hate that term). Some of my shadows come as expected, however some are very strange. For example in this image: ...
0
votes
0answers
42 views

Problem with imageStore to 3D texture on old AMD card

I've been updating an old project that does Marching Cubes using compute shaders, and it fails on my laptop with an old AMD GPU (7670M). After investigating a bit, I found the problem is with writing ...
0
votes
0answers
109 views

Changing coordinate system from texelFetch to textureLod is breaking the algebra

I have a scene rendered using texelFetch() and I am trying to modify the shader to use textureLod() instead. This is the image generated with texelFetch: When I try to change the shader to use ...