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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3
votes
1answer
184 views

How can I GL_SELECT from a gluPerspective-transformed scene?

I'm using JOGL to access OpenGL-methods on an old OpenGL version, because of school. I have written a method which is called before any objects are drawn. This method shows which object is picked. ...
0
votes
1answer
902 views

Screen space decals, converting world to decal space

I'm trying to do screen space deferred decals following the presentation made by Pope Kim about SSDs in WH40K: Space Marine (link). I've gotten to the point where I can render a decal if the bounding ...
5
votes
3answers
1k views

How do I send multiple matrices to a vertex shader?

I'm practising animations using bones/skinning. I am trying to send the shader one matrix per vertex. I can think of these two approaches. Method 1 I have one uniform handle for each bone matrix ...
1
vote
1answer
353 views

Efficient way of loading wavefront models in openGL game

In my game, a RTS game, the units are all wavefront obj. all their animation frames are each seperate wavefront obj file. ie. without any skeletal animation; fully rigid models. So when many units are ...
2
votes
1answer
264 views

How to work with smaller intermediate textures in OpenGL and GLSL?

I'm working on a project rendering water simulated through smoothed-particle hydrodynamics (SPH) with a non-photorealistic look to use in games. In the actual stage of the project everything about ...
0
votes
1answer
290 views

Strange behaviour using VAO (OpenGL 4.0)

I want to display a simple textured Monkey mesh using VAO. Here's the code in the render part first without VAO to see what is the result I'm looking for. Texture *pTexture = ...
1
vote
0answers
153 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 ...
0
votes
1answer
299 views

What are the possible techniques to optimize the lighting pass in a deferred shading renderer? [closed]

I am toying around with "modern" OpenGL (this is my first attempt, I am new to this) and I have been developping my own deferred shading renderer as an exercise. I am using an FBO with the following ...
0
votes
2answers
362 views

translate-scroll repeated 2d texture using opengl shader

I managed to implement an infinite 2d texture scrolling using the following shader. btw I'm using cocos2d-x 2.2.1. The vertex shader: attribute vec4 a_position; attribute vec2 a_texCoord; #ifdef ...
2
votes
0answers
460 views

C++ FPS game collision detection with partitioning system or physics engine? [closed]

I'm working on a small FPS game (as a hobby and for learning purposes, nothing else) built with C++ in OpenGL (from scratch). Documenting online on the kind of strategy someone would approach with ...
1
vote
1answer
539 views

How to draw a plane equivalent to a given btStaticPlaneShape using OpenGL

With all other shapes in bullet, you can easily get the transform from the MotionState which holds the origin, the scale, and the rotation. There seems to be no way to get the same information about a ...
0
votes
1answer
256 views

Opengl Compute Shaders support?

I have a question about compute shaders. My GPU is an AMD mobility Radeon 6490 which as the AMD website says supports OpenGL 4.1. However, when I check for my compatibility version via ...
1
vote
0answers
184 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 ...
0
votes
1answer
117 views

Jittery Rotational Movement with Arcball implementation

I have an assignment where I need to implement arcball using Opengl (~2.0). I have it more or less implemented but I have a some problems/issues/bugs and I'm not sure whats either causing them or how ...
1
vote
1answer
131 views

How to draw or translate into world space?

I've been hacking around with OpenGL, but there's a few concepts which I can not find the answer on. I want to draw three GL_QUADS next to eachoter like so: 1[2][3] I know GL_QUADS are deprecated, ...
1
vote
1answer
387 views

Infinite / Treadmilling Hexagonal Grid

So, I can happily render an infinite square grid by moving said grid whenever the camera moves out of a grid square, auto diff = (cameraTranslation - gridTranslation); bool moveGrid = false; if ...
1
vote
1answer
731 views

SSAO looks wrong

I'm trying to implement SSAO based on this tutorial. My setup: OpenGL 3.2 Forward renderer View-space depth and normal in a single 16-bit floating point texture. The result I get is this: The ...
0
votes
1answer
1k views

How do I move the camera in 2D LWJGL openGL?

I am making a top-down rpg game with the LWJGL but I can't figure out how to make the camera follow the player. I've tryed using GLU.gluLookAt() but it seems to be designed for 3D and when I try it ...
1
vote
2answers
270 views

How can I compute the orbit of one body around another?

I'm attempting to have a planet (with a known mass and radius) orbit it's sun (also with a known mass and radius). It doesn't have to be 100% realistic, but it should be possible that the sun have ...
4
votes
2answers
670 views

Is Batching Geometry Every Frame Always Slower Than Individual Draw Calls

I'm currently have an application that has ~10k draw calls. I implemented a batching scheme where I group all objects that share material, vertex format, etc and pre-transform them by their world ...
1
vote
2answers
402 views

gl_FrontFacing - is there perfomance cost?

If I use gl_FrontFacing in my PS, is there any performance cost during vertex transformation (like cross product from triangle vertices), or is this value computed any time ?
2
votes
2answers
281 views

What is the correct way to draw layered Sprites in modern OpenGL?

So what do I mean by layered sprites? Layered Sprites are Sprites that consist of multiple layers, e.g. you have sprite sheets for the basic Body, the Head, Clothes, Weapons, etc. Well now I wanted ...
0
votes
1answer
97 views

What is the correct Order of Operations on OpenGL 2.0 Loading Texture in condense format?

I have come across a problem when I am loading a single texture onto a single quad, and this problem persisted during the planning phases of my project, before starting my development phase. I am ...
3
votes
1answer
278 views

Texture mapping a complex object on openGL ES

I dont have much experience with openGL ES (or openGL), but i do get the general idea of texture mapping, which is each vertex should be mapped for the relevant UV coordinates of the texture we choose ...
2
votes
2answers
379 views

Batching and Z-order with Alpha blending in a 3D world

I'm working on a game in a 3D world with 2D sprites only (like Don't Starve game). (OpenGL ES2 with C++) Currently, I'm ordering elements back to front before drawing them without batch (so 1 element ...
-1
votes
1answer
74 views

Combine textures with coordinates [closed]

Is it possible to add one texture to another texture, at specific coordinates? Like if I want to add a small texture(16x16) to big texture (1368 x 768) with coordinates ( 100, 100) so the small ...
1
vote
0answers
369 views

Shadow mapping implementation not working? [closed]

I am trying to implement Shadow Mapping in my program using Java/LWJGL/OpenGL/GLSL, but I cannot get it to work properly. Let's start off with a screenshot first, then the relevant code and lastly ...
2
votes
1answer
380 views

How do I draw an animated object in OpenGL ES?

I have a VBO, which I initialise like this (just an example): - (void)setupVBOs { GLuint vertexBuffer; glGenBuffers(1, &vertexBuffer); glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer); ...
1
vote
1answer
163 views

Get the 8 corners of camera frustrum?

I'm doing shadow mapping for directional lights and I'm trying to get 8 corners of the camera frustrum as a bounding box for the geometry, but I have no idea how. The goal is like in the image below ...
0
votes
1answer
399 views

Textures not displaying. Problem with fragment and vertex shaders

Hi i have newbe question. I am sending to gpu textures unit and they dont display. This is simple version of my fragment and vertexshader. (More complicated version also dont work with other textures ...
-1
votes
1answer
255 views

Opengl Obj with multiple textures. Jpg texture don't display

Hi i have problem with jpg textures. DDS is working good but jpg is not. This is my function to load JPG texture. In debuger i see that this works but i dont see anything. char * a =(char *) ...
0
votes
1answer
150 views

why is my OpenGL texture transparent?

I have a terrain in OpenGL, and two textures which I am combining using GLSL mix() function. Here are the textures I am using. Now I am able to combine and mix these two textures, but for some ...
0
votes
1answer
309 views

Drawing Colored Geometry in OpenGL using SDL

First off, I will confess I have asked the same question on stackoverflow, but I think this forum might be a better fit. I am trying to combine 2 things using SDL: Draw a webcam feed via an ...
1
vote
1answer
128 views

recommended shader pipeline infrastructure in core opengl 3.3

I am writing a game project in Go and I am using an OpenGl 3.3 core context to do my rendering stuff. At the moment I have different types of renderers. Each renderer has it's own pair of vertex- and ...
0
votes
1answer
107 views

How can texture packing improve performance?

Let's say I let a user give my library (a GUI system) multiple textures for rendering elements. What would be the performance impact of rendering with each of those textures separately versus, say, ...
0
votes
2answers
241 views

How to mix pixel colors in Shader?

I have a pixel that have a colour RGB. This color is calculated by the shader and can be anything. How can I override this color by a colour I choose. If my pixel is white it's simple, I can do this: ...
2
votes
1answer
255 views

Workaround the flip queue (AKA pre-rendered frames) in OpenGL?

It appears that some drivers implement a "flip queue" such that, even with vsync enabled, the first few calls to swap buffers return immediately (queuing those frames for later use). It is only after ...
0
votes
1answer
879 views

Simple curiosity about glDrawElements function

I've written a very simple OpenGL program displaying a white cube. To do the job done I recovered vertex position and indice data from an OBJ file that describes my cube. Here's the OBJ file content : ...
0
votes
1answer
209 views

Combine framebuffer-textures to default framebuffer

I know frame-buffers are not textures themselves, but they do contain a texture, given they are set up correctly, which I believe mine are, as: (status == GL_FRAMEBUFFER_COMPLETE) returns true. ...
0
votes
1answer
1k views

Directional shadow mapping view/projection matrices

I've got shadow mapping with directional lights working, but I believe I am constructing the view/projection matrices wrong. Here's how I build them: Mat4 viewMatrix = ...
2
votes
1answer
2k views

How to achieve anisotropic filtering

I am loading a texture and using glGenerateMipmap() on it to achieve some level of mipmaping. I get different result on nVidia gt 555m, and on Intel HD 3000. The texture rendered by nVidia is not ...
0
votes
1answer
445 views

Texturing a PyOpenGL 3D Cube with PySDL2

So, I've just started learning OpenGL with PySDL2, and I've created a class that will create a cube to the window that I've created with PySDL2. What I'd like to do now, is to figure out a way to ...
7
votes
3answers
2k views

How long does it take for OpenGL to actually update the screen?

I have a simple OpenGL test app in C which draws different things in response to key input. (Mesa 8.0.4, tried with Mesa-EGL and with GLFW, Ubuntu 12.04LTS on a PC with NVIDIA GTX650). The draws are ...
0
votes
1answer
157 views

When should rendering be performed during a frame?

When working with OpenGL or DirectX, should draw calls be done all at once, at the end of the update loop, or is it better to have draw calls occur during the update loop rather than just at the end?
9
votes
3answers
1k views

How can I create a glitter effect?

I am trying to create a glittering effect for my realtime shader but I don't know how. Here is one example, and another example. What technique can I use to implement this?
0
votes
1answer
532 views

How to use FrameBuffer objects (OpenGL)

I want to draw a 2D scene and after the scene i want to draw some light effects. When i draw some light, i create a FBO, draw in it and when finished with drawing, i want to create a texture where i ...
1
vote
1answer
103 views

Run OpenGL shader on part of a texture

How do I run an OpenGL shader on just a portion of an off screen texture and leave the rest of the texture unmodified? Are there any calls that restrict the sampled pixels to just a rectangle or do I ...
2
votes
3answers
482 views

Order of render with transparency opengl

I tried to render using different render configurations (GL_BLEND_FUNC()) but I couldn't get the back object to render in certain angles. The first screenshot here shows one angle where the back ...
1
vote
0answers
119 views

FreeGLUT keyboard IO timing and synchronization

Using FreeGLut's keyboard callbacks, glutKeyboardFunc(); glutKeyboardUpFunc(); glutSpecialFunc(); glutSpecialUpFunc(); When in the glutMainLoop pipeline do these functions get called? In other ...
0
votes
1answer
643 views

LWJGL Adding Textures with VBOs

I'm currently trying to texture a cube, but I am having no luck determining what the next step should be. I can load an .obj model from Blender into my LWJGL program just fine, and I can even make a ...