OpenGL is a graphics standard and API which targets the desktop and workstation markets. It is designed to be easy to accelerate with dedicated computer hardware, and hence most implementations give greatly improved performance over traditional software rendering. Currently, OpenGL is used for ...

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7
votes
0answers
473 views

Variance shadow maps don't want to render properly

I've implemented VSM (and also ESM) in my engine but results are for me not as I expected and saw in many examples published on network. I set filtering of shadow maps to GL_LINEAR but when I compare ...
4
votes
0answers
36 views

Irradiance Map ( Irradiance environment map)?

As irradiance map is generated for every possible normal for all the texels in environment map (as every texel act as a light source) so that we can look up irradiance map, based on normal of fragment ...
4
votes
0answers
76 views

OpenGL: Frame partially jumps back and forth

I'm working on a project with SDL and OpenGL. The game works great on Windows, Linux, OS X and iOS. However, the Android version is showing a problem on my phone in particular. I have tested another ...
3
votes
0answers
44 views

Spherical Area Lights do not match reference

So I'm adding spherical area lights to my application, and comparing my results with mitsuba, I am getting some differences (left is my approach, right is mitsuba - a pathtraced reference): What I ...
3
votes
0answers
62 views

How do I align the cube in which shadows are computed with the view frustrum? (“View Space aligned frustum”)

Short and concise: Given 8 world space positions that form a cube of arbitrary size, position and orientation and given an arbitrary light direction. How do I compute the View and Projection matrix ...
3
votes
0answers
69 views

Draw Edges in OpenGL

I use blender game engine, and blender use openGL for graphics. How can I draw lines around all 3D objects? Would this be a job for a filter? Mainly, I want my end result to look drawn. I found this: ...
3
votes
0answers
81 views

Is it possible to use OpenCL in libgdx?

Been looking for a way to implement some OpenCL stuff in my libgdx project. It's possible via LWJGL which libgdx is based on, but it's only for the Desktop environment. Would like to have it cross ...
3
votes
0answers
83 views

How to draw Shadow Volumes in one draw call?

I've got a simple app that draws 3D cubes using instance rendering and I'm implementing Shadow Volume. Each cube's vertex, uv, normal and index data are statically stored in 4 vertex array buffers. On ...
3
votes
0answers
110 views

OpenGL Planet Generation - Simple Matrix Issue (Planet “Spins” With Mouse)

I originally asked this question on StackOverflow & was directed here by a commenter. Im currently working on a OpenGL planet rendering. I'm using the Tessellation pipeline. So far things are ...
3
votes
0answers
238 views

How much is atomicAdd slower than an atomic counter?

I am considering replacing an atomic counter in my shader code with a SSBO an atomicAdd operation. What I need to know is the difference in performance of these two. I know the atomic counter executes ...
3
votes
0answers
117 views

Render on texture with alpha 0 for the background colour

Sorry if the question is stupid but I am very new to opengl. I render on a target a scene with a couple of object on a background that is nothing more than the clear colour (which is ...
3
votes
0answers
707 views

AlphaToCoverage + Alpha Blending = Artifacts

I'm experiencing a strange problem using OpenGL SampleAlphaToCoverage mode. There are rendering artifacts when using alpha-blending on pixels that have been rendered using alpha-to-coverage - and I ...
2
votes
0answers
54 views

GLSL shader with light colors wrong on nvidia optimus

So, I built some code to draw a spinning cube with a red light on the right side, and a blue one on the left. I run it on my laptop with optimus graphics, and on my desktop with nvidia. On the laptop, ...
2
votes
0answers
152 views

Jagged light bleeding where surface is roughly parallel to shadow mapping light direction

I am using Unity but this question might not be proper to this engine. I have projected the shadow map onto this sphere but there are grazing shadows. Is it possible to avoid it or to correct it as I ...
2
votes
0answers
78 views

Texture coordinates for custom geometry in SceneKit ios9

I am trying to texture the a custom plane shape I created in scenekit on iOS9. I need the texture to spread out and stretch over the entire surface. I have a vertex and fragment shader on an ...
2
votes
0answers
43 views

Formula for model matrix with mouse coordinates

I'm trying to create a simple OpenGL app where I can drag objects with the mouse. The code below is based on a raycasting algorithm covered here. I'm using the diff between the current mouse coord ...
2
votes
0answers
114 views

Shadow mapping - Can't get the right texture coordinates

I'm trying to implement shadow maps for Spotlight's, but alas I can't get them to work. I have verified that my fragment shader is getting the shadow map texture. I can sample from it in the ...
2
votes
0answers
212 views

OpenGL Depth Cubemap with Geometry Shader Not Rendering Correctly

I was having some trouble with cubemaps in OpenGL, and was hoping to get some help. I've been following a tutorial about point light shadow mapping using cubemaps, where a geometry shader is used to ...
2
votes
0answers
172 views

Texturing Objects in OpenGL

Using OpenGL tutorials found here, I constructed an .obj file loader as well as a texture file loader using SOIL. I have an issue with drawing a textured object. (Shown here) Assuming I created the ...
2
votes
0answers
52 views

Opengl Skybox Texturing Error

I'm using cubemaps to render a skybox in my game. Thinking this would be a simple task I threw some stuff together using the tutorials I found online, particularly this. Taking all of this together, ...
2
votes
0answers
85 views

OpenGL enabled Java game not detected by Fraps

Recently I found out that I could enable OpenGL hardware acceleration in my java game with the line System.setProperty("sun.java2d.opengl", "True"); Initial tests showed a big boost in performance. ...
2
votes
0answers
140 views

OpenGL: Avoid geometry shader for cubemap framebuffer

I want to render an environment map into a cubemap framebuffer but I dislike the fact, that I have to use the geometry shader to set gl_Layer because the geometry shader would be a basic passthrough ...
2
votes
0answers
66 views

Tangents face the same direction on opposite sides of mesh

I have noticed that the tangent vectors that I am calculating are not always facing the correct direction. The tangents on the left and right of the mesh both face the same direction. Here is a ...
2
votes
0answers
2k views

Arcball 3D camera

I have checked multiple threads before posting, but i havent been able to figure this one out. Ok so i have been following this tutorial, but im not using glm, ive been implementing everything up ...
2
votes
0answers
691 views

How to implement OpenGL triple buffering of buffer objects to avoid stalls?

I'm trying to implement the triple buffering described here. The intent is to gain higher frame rate by avoiding waiting for glBufferSubData() to finish. My understanding is that this is how to ...
2
votes
0answers
454 views

glFramebufferTexture2D gives corruption with cube map textures

I am using glFramebufferTexture2D with cube map textures but it gives corruption in texture. draw_cube() function works perfectly when i draw that on default framebuffer. GLenum ...
2
votes
0answers
557 views

Per fragment lighting with OpenGL 4.x tessellated model

I'm experienced with OpenGL 3+. I'm dabbling with tessellation shaders and have now got to a point where I have a nicely tessellated teapot/plane demo (quick look here) As can be seen from the ...
1
vote
0answers
23 views

Applying different materials to an object

I'm currently implementing an Object Loader for the Wavefront File Format (*.obj). When exporting a model (with associated materials) from blender, a material for a group of faces is specified like ...
1
vote
0answers
28 views

How to calculate specular contribution in PBR?

I'm trying to implement PBR in our project (we started a small game engine for academic and learning purposes) and I cannot understand what is the right way to calculate specular and diffuse ...
1
vote
0answers
30 views

OpenGL texture not loading onto the model

I am still learning and I'd like to apologize if I don't explain something clear enough or anything like that. please forgive me :) So I am experimenting with 3D graphics for my university ...
1
vote
0answers
53 views

Slick2D fails to load small textures

I'm trying to load a small 32x32 png texture using Slick2D, however it doesn't seem to render correctly. What's odd is that larger textures do load correctly. The 32x32 texture I'm trying to load: ...
1
vote
0answers
89 views

Turning On/Off Vsync no longer working when rendering to an offscreen buffer

I have this reaallly strange issue that as soon as I render to an offscreen framebuffer I am no longer able to toggle VSync while my application is running. I am using OpenTK as the opengl wrapper, ...
1
vote
0answers
38 views

Drawing multiple polygons with vertex buffer object

I tried to create program in which I would draw multiplepoygons here is fragment of what I have done: GLuint VertexArrayID; exampleof drawing triangle(I have more polygons, like circle, and so ...
1
vote
0answers
54 views

Front Face Culling with Shadowmapping

To avoid shadow acne I usualy use front face culling which works great. But for my current implementation the mesh is a quite complex terrain (depending on the lod level) and than the shading (dot ...
1
vote
0answers
40 views

Cell height with heightmap for collision detection

Hello everyone I'm programming a game with c++ and openGL. My world is generated from a heightmap (100x100 matrix with values 0-255) and now I need a function that returns the actual height based on ...
1
vote
0answers
38 views

blending with OpenGL glBlendFunc and glBlendEquation

I want to draw a bunch of images in front of a background. Where images overlap, I want those to be blended together (for now, using a mix of 0.5 source * 0.5 destination color every time an image ...
1
vote
0answers
137 views

OpenGL Render Queue Design

I am currently designing the rendering system for a 2D game built in C++ and OpenGL, and am unsure about how to go about implementing a sorting procedure to maximise efficiency and minimize OpenGL ...
1
vote
0answers
70 views

Subsurface Scattering - Transmittance

I have a question related to SSS and especially transmittance. I've looked at several papers about that topic, most of them from Jorge Jimenez, which are very interesting and, I admit, a bit hard for ...
1
vote
0answers
156 views

How to use OpenTK (OpenGL) with MonoGame?

So I've been making a snake game using MonoGame (DirectX Only). I added movement, controls, feeding and growing in length. I wanted to add smooth animations to the game because the snake is just made ...
1
vote
0answers
48 views

Implementing Separating Axis Theorem in 3D with C++/OpenGL

Using an Octree data structure provided to me by an acquaintance that gives min/max bounding box values, I've been able to write an algorithm that takes the global centre points, face normals and half ...
1
vote
0answers
25 views

GL.Scissor not working as expected

I have some code for rendering a button in an application and I want to clip the text if it's wider than the button itself. Here a bit of code to describe what I'm doing: ...
1
vote
0answers
48 views

OpenTK crashes with Mono

I've implemented OpenTK as a secondary renderer which would let me support Mac/Linux only to realize that for some reason, even without any modifications (new MonoGame project), the application would ...
1
vote
0answers
72 views

Point Light shows black box & rect (PointLight not working) - libgdx 3D

I am creating a 3d scene currently a box and rect, and trying to enable lighting. When i create a PointLight and add it to Environment everything turns to black color? all i want to do is ...
1
vote
0answers
44 views

Consistent Shadow Map Filtering

I want to filter my shadow map generated by PSSM, but the problem is that I have a inconsistent filter size. The problem is that the shadow map sources rotate to find the best fit for the camera ...
1
vote
0answers
61 views

glTextImage2D with GL_UNSIGNED_BYTE giving weird results while with GL_FLOAT just works, driver bug?

Update: OK, not being able to see the textures loaded by FreeImage was just one of the common mistakes when using modern OpenGL. My texture loading code did not set GL_TEXTURE_WRAP_S/T and ...
1
vote
0answers
110 views

OpenGL RayCasting and Intersection with plane

I have been trying for a couple of days to raycast. I have a Renderable/Texture/Primitive/Whatever placed in the WORLD at 0.0f,0.0f,0.0f, and when I click the mouse I want to know at what X,Y ...
1
vote
0answers
158 views

Cube map or 2D texture map

I'm trying to map quadsphere with COBE spherical cube (CSC) projection in OpenGL (wanna map planets). I managed to create a 2D texture and it works well except seams at edges. Then I learned that ...
1
vote
0answers
200 views

Restart a 2D game - OpenGL, GLUT

I started learning OpenGL and GLUT by making a snake game. The problem I encountered is that when I press the "new game" in the menu, the window has to be resized so that the content of the window to ...
1
vote
0answers
224 views

Implement Candy Crush like level graph

I want to implement road-map like level graph where in you can see what level are you and your friends are on. Just like we see in Candy Crush Saga.For people who have not seen Candy Crush Saga, ...
1
vote
0answers
86 views

Libgdx - Transparent color over texture

I am attempting to tint a texture a color but I want the texture to show under the tint. For example, I have a picture of a person but I want to tint them a light green and not change the transparency ...