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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6
votes
0answers
129 views

Tone mapping and eye adaptation - pale colors and darker image

I'm trying to implement tone mapping along with eye adaptation and HDR. Actually I implemented this already but I'm not satisfied with result and I think that I made something wrong. My final image ...
4
votes
0answers
131 views

problem loading Collada DAE model using Assimp in OepnGL 4.4

I am loading a model in my OpenGL application using Assimp library like this : bool CGameObject::LoadModelFromFile(char* sZFilePath) { std::string fn = sZFilePath; std::string td = "\\"; std::string ...
3
votes
0answers
123 views

Skeletal animation in OpenGL

I'm using Assimp to do skeletal animation in my OpenGL application. I used Blender to export this one-boned model to a COLLADA file: The model has only one bone, called arm bone, that controls the ...
3
votes
0answers
575 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
29 views

Cannot convert bitmap to texture

I'm doing a little C# / OpenGL project and I can't manage to load textures properly. So here is my texture class : public class Texture { public String Filepath; private int TextureID; ...
2
votes
0answers
60 views

How to handle the birth and death of particle without reading from the buffer

I've implemented a simple particle system where each particle has a position, velocity, age and lifespan stored in different SSBOs. Most of the data including all the position, velocity and age is ...
2
votes
0answers
76 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 ...
2
votes
0answers
54 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
1k 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
384 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
429 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
27 views

Find camera coordinate of vanishing point

Given a vector and a camera (position, angle, up vector, field of view, etc), how would I find the vanishing point of the vector in camera space?
1
vote
0answers
39 views

Drawing fonts with LWJGL3 with OpenGL

I'm very sorry if this question has already been answered, but since I've been struggling with this for many days I thought I'd give it a shot here. My goal is to somehow render some text on the ...
1
vote
0answers
18 views

ThreadAffinity being changed by OpenGL / ChoosePixelFormat

If I change thread affinity and then create the window used in my OpenGL game it changes the thread affinity to something else. I tracked down the exact API call (ChoosePixelFormat) which changes it ...
1
vote
0answers
64 views

Transformed Vertices have wrong Z Axis

For quite some time I've been working on my open 3D game engine, to learn how this stuff works. You can see the full codebase relating to my problem here on GitHub. I'm using an OpenGL 3.3 Core ...
1
vote
0answers
43 views

Confused About My Code Suggesting The Normal Matrix Is Equivalent To The ModelView Matrix

I'm learning environment mapping in OpenGL by following this page. In his vertex shader, the author calculates the vertex normal in eye space with the following code: nEye = vec3(viewMatrix * ...
1
vote
0answers
39 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. ...
1
vote
0answers
28 views

postprocessing shader destroying viewport on linux?

Basically I implemented gamma correction into a q3 based game to get rid of the annoying SetDeviceGammaRamp. On windows and macosx everything works fine, but on linux it draws garbage. It looks like ...
1
vote
0answers
41 views

Performance issues with different types of uniform buffer

I've tested different buffer layouts, because I'm confused about some performance issues. That are my test buffer (OpenGL 4.1, GLSL 410, GT 750M, MacBook Pro): Test #1: Using fixed struct buffer with ...
1
vote
0answers
59 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 ...
1
vote
0answers
59 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 ...
1
vote
0answers
77 views

glGetUniformLocation returns 23724032

as the title says, I have a problem using glGetUniformLocation call that returns, for the following code, the value 23724032. I'm writing a little engine and the draw function of my models is: void ...
1
vote
0answers
94 views

Uniform Buffer Binding-points

I believe Uniform Buffers/Blocks has been the hardest thing to grasp in OpenGL. Hopefully this will be my final issue regarding this. I have created a uniform buffer that contain data of Light ...
1
vote
0answers
75 views

How can I do ambient occlusion for simple meshes with few vertices?

I want to do ambient occlusion for some simple buildings. Since simple buildings have very few vertexes, how can I get good results? Is it possible with a per-vertex AO implementation?
1
vote
0answers
68 views

Smooth seams and banding of overlapping lights in deferred rendering

I have finally managed to get on screen multiple lights with a deferred renderer, but the result is somehow disappointing. In particular I have severe banding problem Other than having clear ...
1
vote
0answers
89 views

Why is my diffuse lighting changing with camera position?

I am trying to do lighting in view space, but I am afraid I have an issue. I calculate the normals as: N = norm_mat * vec4(vert_norm,0.0) where norm_mat is the transpose(inverse(model_view_mat)). ...
1
vote
0answers
88 views

How do I fill a shape with a texture in Libgdx?

I am making a 2D racing game. I want to fill the area of the ground object with a texture. I have the shapes of the ground (a Box2D shape). If I make images of the ground with textures, it uses a lot ...
1
vote
0answers
62 views

Sprite framework binding multiple textures

In an attempt to batch render as many quads (sprites) as possible, I'm instance rendering a single unit-sized quad and passing in a buffer of per-instance data that includes width/height, texture ...
1
vote
0answers
71 views

Mouse click coordinates not mapping to Box2d world

I'm using Box2d in Java with OpenGL, trying to detect if a mouse has clicked on a Body. But having trouble mapping mouse coordinates to Box2d world. I have a Body positioned at 20.0f, 30.0f in the ...
1
vote
0answers
142 views

OpenGL Bump Map — Texture artifacts ?

I am learning OpenGL (and learning the math behind it) and I'm making a simple OBJ viewer, nothing fancy. I have diffuse, specular and ambient light/texture working fine and now I am implementing the ...
1
vote
0answers
104 views

Shadow map shimmering, indexing outside the shadow map

I have tried to reduce shadow shimmering/flickering using technique described here: http://msdn.microsoft.com/en-us/library/windows/desktop/ee416324%28v=vs.85%29.aspx I works as I want and shimmering ...
1
vote
0answers
167 views

Easy way to set face colors with indexed VBOs?

I'm loading OBJs, which lend themselves well to setting up as indexed VBOs, since each vertex is only defined once and then a face definition will reference the same vertex more than once when they ...
1
vote
0answers
112 views

Rotating a scene around a fixed axis

I am looking for a way to move my scene so that when I translate forward/back/left right it moves directly up/down/left/right on the screen. Currently it does do that until I rotate (by anything ...
1
vote
0answers
47 views

Android OpenGLES, getting number of fragments passed depth test/Occlusion Query?

Afeter reading many blogs and searching on Internet, I did not get any sloution for getting number of fragments/pixels which are occludded or not occludded of the object on OpenGL ES3.0 Android ...
1
vote
0answers
145 views

OpenGL - Texture disappears

I'm making a simple program with C++, SDL and GLEW. So far it is going great but I ran into a weird problem. One of my four textures would not show up on screen even though it used the same code as ...
1
vote
0answers
267 views

Is it reasonable to use a 2D texture as a lookup table in GLSL

I need a lookup table in a shader. The input values would be color values and the output other color values. Something like: uniform float lut[256]; color = vec3(lut[int(color.r*255.)], ...
1
vote
0answers
290 views

implementing shadows into my 2D GLSL-based lighting system

I'm writing a lighting system in OPENGL using GLSL shaders, and I'm pretty happy with the light casting I have so far, but I'm totally stuck on casting shadows. Everything I've found online on this ...
1
vote
0answers
126 views

OpenGL/GLM Camera

I want to make a camera that can freely look and walk on X/Z plane and rotate 360 degrees. I'm using OpenGL and the lookAt function from the GLM library to create the view matrix. I've looked through ...
1
vote
0answers
217 views

How to shade hair (line segments) correctly in GLSL

I render my hair geometry in line segments. The problem I have is with the correct shading of the hair. From what I've read I understood that I need the direction of the line segment and the ...
1
vote
0answers
126 views

Creating a voxel chunk with a VBO - How to translate the coordinates of each block and add it to the VBO chunk?

I'm trying to make a voxel engine similar to minecraft as a little learning experience and a way to learn some opengl. I have created a chunk class and I want to put all of the vertices for the whole ...
1
vote
0answers
159 views

Different way to pass uniforms to seperate draws in glMultiDrawElementsIndirect

Given OpenGL version 4.3 and GLSL 430, what would be the best way to pass a matrix to each model in a draw call to glMultiDrawElementsIndirect? I am thinking of going the way of a TBO and indexing it ...
1
vote
0answers
249 views

Android: Hardware Scaler

I was reading through this: using-hardware-scaler-for-performance and am a little confused by it. It says all you need to do to invoke the scaler is to set it like so: surfaceView = new ...
1
vote
0answers
296 views

How can I reduce draw calls when using glBufferSubData and DYNAMIC_DRAW?

At first I had the problem where I had about 150 rectangles rendered every tick. I only used STATIC_DRAW and glBufferData. I added support for DYNAMIC_DRAW and glBufferSubData and now I have a very ...
1
vote
0answers
128 views

Text alignment in OpenGL with FreeType2

I'm trying to implement font rendering and have got into some trouble with glyph metrics. Here's the code where I get the metrics: Glyph gl; gl.width = face->glyph->metrics.width / 64; ...
1
vote
0answers
212 views

What's the best way to set up an OpenGL draw loop in windows?

On mac os x, there's a way to pass the system a function pointer that is triggered at an ideal time to start your drawing code. These are the CVDisplayLink tools. I'd like to understand how to do ...
1
vote
0answers
107 views

Converting signed normalized integer to unsigned normalized integer image format

Given I have my texture data in client memory as signed normalized integers. I want the samples in the shader in the range [0,1]. Can I simply specify: format = GL_RGBA; internalFormat = GL_RGBA8; ...
1
vote
0answers
132 views

3D Camera Y-Axis wrong angle

I am trying to build a camera class, though I am running into a problem. When I move the camera above/below, and try to move towards the ground, I am moved off in what seems to be about 45 degrees in ...
1
vote
0answers
303 views

Rendering portals using stencil buffer

Due to this question I have changed the method of rendering portals. Before I was using FBO and rendering to a texture, but somehow I failed. Now I switched to a stencil buffer method. My problem is ...
1
vote
0answers
147 views

Shadow maps, reducing “shimmering”

I'm doing shadow maps, and my shadows move around, "shimmer", when I move around the camera. It is difficult to spot on still images but very much noticable in motion. I read an MSDN article ...
1
vote
0answers
176 views

How to fix problem in serpentine case using Blinn/Loop algorithm

I'm trying to implement Blinn/Loop algorithm to render cubic bezier on shader. I calculate the curve type using code below (v0, v1, v2, v3 are cubic bezier segment): CurveType ...