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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2answers
237 views

Loaded OBJ Model Will Not Display in OpenGL / C++ Project

I have been experimenting with new effects in game development. The programs I have written have been using generic shapes for the visuals. I wanted to test the effects on something a bit more ...
1
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1answer
129 views

OpenGL and atlas

I'm trying to draw element from a texture atlas with OpenGL ES 2. Currently, I'm drawing my elements using something like that in the shader: uniform mat4 uCamera; uniform mat4 uModel; attribute ...
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1answer
71 views

Correcting Lighting in Stencil Reflections

I'm just playing around with OpenGL seeing how different methods of making shadows and reflections work. I've been following this tutorial which describes using GLUT_STENCIL's and MASK's to create a ...
1
vote
1answer
40 views

Having trouble setting color in fragment shader

For some reason, the color isn't applying to the object. Here's my fragment shader code. There's probably something obvious wrong with it that i'm not seeing. #version 330 core out vec3 Color; ...
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0answers
93 views

Moving objects smoothly, bad perfomance

I just finished developing my mini-game on Android and I got some questions about perfomance and generally "how to": If I have 25+ objects on the creeen (just a polygon with 7-8 angles) its starts to ...
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1answer
92 views

How does OpenGL determine different outputs with shaders?

Lets say I have this GLSL code: #version 330 out vec4 outputColor; void main() { float lerpValue = gl_FragCoord.y / 500.0f; outputColor = mix(vec4(1.0f, 1.0f, 1.0f, 1.0f), ...
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1answer
124 views

Transparency in opengl - texture with alpha, color from background [duplicate]

I have to draw texture with transparent areas on square. But I don't want this transparencies to take color from this polygon, but from the background. Do you have any good tutorial to achieve it? ...
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1answer
133 views

Getting the Ray position from View and Projection Matrix

I'm having some trouble calculating the direction and position of the ray from my matrices. I have tried some things such as: private Vec3 getPick(Mat4 projection, Mat4 view) { Mat4 ...
2
votes
1answer
110 views

How to make OpenGL rendering resolution independent from its window context resolution?

Can the rendering resolution of OpenGL and the window size (at least for the Windows OS) be separated? For example, I may only want to render at 400x300 resolution, but I want my window size to be ...
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1answer
93 views

Correct GL settings to mix 2D and 3D rendering

I'm programming a 3D game engine with 2D GUI. The GUI objects have partially transparent textures and the transparency works more or less. The sky color is rendered in transparent areas of the ...
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0answers
67 views

Alternative to z-fail [closed]

This question is less technical but maybe someone had similar thoughts. I am wondering if the following algorithm still harms the stencil shadow patent? It is concerned with the invention of a "new ...
1
vote
1answer
105 views

How to use LWJGL Vertex Buffer Objects?

I have been learning how to make a game with LWJGL for a while now by following YouTube tutorials online but I've recently been having a problem understanding Vertex Buffer Objects. I've looked at ...
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1answer
82 views

DirectX Bullet Tracer Effect

I'm wondering if anyone knows some common and efficient ways to do a fast tracer for an instant bullet. I've seen people speak on forums of using primitive lines with DirectX, but I doubt this ...
2
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1answer
228 views

3D Camera Rotation

Please, forgive me, but I need help and I've been stuck on this for a few weeks now, I'm making no progress and everywhere I go and I see a different answer, everything I try doesn't work. I've had ...
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vote
2answers
125 views

OpenGL drawing, breaking down triangles

if I want to use no textures in a game (i.e png's), would I just break down my drawing into triangles and combine them the way I want? I found this in Google Images.
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1answer
305 views

Cascaded shadowmapping problem with split distances

I'm doing cascaded shadow mapping and I have problem. From the cameras position, the splits are [camPos, 6], [camPos+6, 12], [camPos+12, 18] and [camPos+18, 100]. The "mSplitDistance" variable is the ...
3
votes
2answers
403 views

Why does my machine render OpenGL using my onboard chipset instead of my graphics card?

I'm following an OpenGL tutorial series at opengl-tutorial.org, but have run into a problem: The following lines: glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); ...
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0answers
77 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
1answer
66 views

How to create more vertexes from within a shader in OpenGL?

when rendering voxels in octrees, the only information necessary is the current octree-level, -position and colour/texture. But one has to send eight vertices to the rendering pipeline in order to ...
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1answer
77 views

Is there a way to use other fonts, besides the default ones in OpenGLUT?

I'm using OpenGLUT functions like glutBitmapString to render sentences and words in a game. However, there is a limited set of fonts to use and I need some bigger size fonts. Is there a way to add new ...
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1answer
86 views

OpenGL - Disable Anti Alias

I can't find anything on how to hint to the driver to disable any antialias. I'm using a very minimal passthrough setup yet I notice my driver is still doing what looks like MSAA. I want to disable ...
0
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1answer
107 views

OpenGL 3.3: render to framebuffer w/o depth attachment

I want to render my scene to a framebuffer and store the RGBA values in a texture. For this, I attach a texture to GL_COLOR_ATTACHMENT0. When I define a GL_DEPTH_ATTACHMENT texture as well, everything ...
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1answer
72 views

Imageeffects: No need for Framebuffer? Just use Textures and Shaders?

I am doing simple Image Effects, and always i see in examples, that people are binding textures to framebuffers. Why can't i just use textures? So the process would be. 1) Input Texture 2) Shader: ...
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1answer
101 views

Why is the light following my camera around?

I have implemented a simple Phong shader without specular highlights for now (just ambient + diffuse components) The problem however, is that the calculations seem to be done in camera space; as I ...
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0answers
40 views

Why isn't my texture changing after calling display list?

I can't bind another texture after calling glCallList. It does nothing. However if I change texture inside the list, it works.
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1answer
81 views

Distorted LookAt When Looking Up or Down?

I have a weird problem and I have no idea what's going on with it. Recently started doing some OpenGL programming, going pretty well, hit some rough spots but worked my way through them and otherwise ...
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0answers
156 views

opengl volumetric billboard implementation: general idea + geometry shader

A while ago I decided to implement the volumetric billboards technique in my university project (C++ & OpenGL 4.3). I passed the subject but failed to implement the mentioned technique. I'd like ...
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1answer
67 views

How do I follow this glsl1.2 + lights + shadows tutorial?

I am following this great tutorial but I have many questions. Let's see if I understand the basic idea. 1. I must create the same number of FBOs that lights (maximum 8). 2. I must create the same ...
3
votes
2answers
117 views

GLSL: sampler2D fallback to constant color?

So I have the following situation: I'm sharing a blinn shader accross many meshes. Some meshes have specular & normal maps, others do not. I'd like to, without making the shader code too ...
1
vote
2answers
200 views

How to reduce/remove graphical artifacts?

Question I'm working on a side-scrolling game that has a 2D grid for rendering to the screen. I'm using OpenGL, and I've optimized my game so that nothing invisible is attempted to be drawn. As of ...
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votes
1answer
207 views

making a cone roof look hollow

How can I make a cone roof look hollow when viewed from underneath? I am trying to create a cone shaped roof, but the cone does not look much like a roof, the edges of the roof seem to blend with ...
2
votes
2answers
145 views

How can I determine the pixels covered by a transformed triangle (without drawing it)?

I have three points that form a triangle in a 3D scene. I want to apply an arbitrary rotation/translation transformation to this polygon and later check in which pixels of an image they would be ...
5
votes
1answer
146 views

How can I implement real-time mutual object reflection?

So, given a scene like this (cubemap skybox with "real" spheres) Everything looks great, except for the fact that the spheres don't reflect each other. What's a good way to go about this? The ...
5
votes
2answers
267 views

Are display lists faster than VBOs?

I'm making a voxel rendering engine. My "chunks" are 32 * 32 * 256 blocks and I can render a 16 * 16 square of them (which corresponds to Minecraft's maximal render distance). I'm using VBOs holding ...
2
votes
2answers
241 views

3D position to UV coordinates in fragment shader

I am interested in converting an arbitrary 3D position computed at run time in the fragment shader to its corresponding UV coordinates. Notice that the 3D position I am interested in is NOT a 3D ...
3
votes
2answers
220 views

Is there any reason why there isn't a cross-platform implementation of DirectX?

Similar to how Mono can compile C# to various platforms, why isn't there an API that conforms to DirectX's specifications but can produce binaries for all platforms? I understand that there is OpenGL ...
14
votes
4answers
1k views

Why do we use 4x4 matrices to transform things in 3D?

To translate a vector by 10 unit in the X direction, why do we have to use a matrix? We can just add 10 to the mat[0][0], and we got the same result too.
1
vote
1answer
92 views

In glsl, how do indices work?

I have made a vertex shader and fragment shader and kind of know how they work, and I know that you specify what index you want your vertices to be in inside the shader program. So if the vertex was ...
0
votes
0answers
70 views

Finding the correct transformation in vertex shader for easy sprite drawing

Before we begin the question: Here are the necessary meta information: I want to use JOGL / OpenGL to create a library that is only, and I repeat only, able to draw and manipulate 2D sprites on a 2D ...
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0answers
42 views

Easier way to clip a spritesheet

I have been learning OpenGL slowly for the past few weeks through LazyFoo's tutorials, and I've come to the texture clipping section. I think his explanation is fine, but not quite enough for me to ...
0
votes
1answer
108 views

(LWJGL) Pixel Unpack Buffer Object is Disabled? (glTextImage2D)

I am trying to create a render target for my game so that I can re-render at a different screen size. But I am receiving the following error: Exception in thread "main" ...
1
vote
1answer
95 views

glOrtho setting view

I am duplicating this thread from stackoverflow, please remove it if that is not allowed. I'm completely new in OpenGL. I have this problem: I have quite a complicated scene, and I am looking at it ...
1
vote
1answer
417 views

Anti Aliasing: How to implement supersampling in OpenGL?

I'm learning OpenGL by working on a small Oculus Rift project, which implies, anti aliasing is everything :). Since the application of the barrel distortion shader requires rendering to a framebuffer ...
2
votes
0answers
219 views

OpenGL drawing 500k triangles [closed]

I want to render big, izometric 2d map (using ortho projection). I am using OpenTK and aiming for OpenGL 3.3. Perfect option would be to draw 512x512 map of tiles, which is 262144 blocks -> 524288 ...
7
votes
3answers
320 views

Terrain & Multi-Texturing

I'm using OpenGL (Version 4.4) (and C++ if that matters). I've created a terrain renderer, the terrain is stored as a 3D scalar field (isosurface/voxels). It uses a slightly modified version of ...
3
votes
2answers
132 views

Blending semi-transparent images while not stacking their alphas

In libgdx/OpenGL ES I want to render multiple semitransparent textures while keeping the alpha still semi transparent. For example If I render a 0.5 alpha circle on top of another 0.5 alpha circle, ...
2
votes
1answer
400 views

How can I forward GLFW's keyboard input to another object?

I'm having trouble trying to execute keyboard events in a another class with GLFW3. The problem I'm having is that GLFW3 uses a static function for input as shown: static UI u; ... ... static void ...
0
votes
1answer
196 views

OpenGL Reconstructing Position from Depth

I know this has been asked a lot of time before but none of those answers fixed my problem. I try to implement deferred shading and to do so I need to reconstruct the world space position from the ...
0
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0answers
52 views

How expensive is binding an OpenGL buffer object that is already bound?

I'd like to know how slow/fast it is to call glBindBuffer() on a buffer that is already bound to the same target. Or is it better to cache this information in my code? Would it be faster to always ...
0
votes
1answer
160 views

Why do I get “function not supported” exceptions for OpenGL 3.2 functions using LWJGL?

I am currently having an issue trying to initialize a frame buffer using LWJGL. When I try to call GL32.glFramebufferTexture(int, int, int, int) it throws a "Function is not supported" error. I have ...