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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197 views

Artifacts rendering high-poly procedural meshes with OpenGL

I am having some issues when rendering some procedural generated meshes. There are some really wierd artifacts when rendering high-poly count meshes (not that much actualy). I have been able to ...
2
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2answers
907 views

Opengl Quad Tessellation Control Shader

I have the generic tessellation evaluation shader for triangles but I need to make it work for quads. Is there any chance someone could explain what is happening here and point me in the right ...
2
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1answer
442 views

How to improve Batch Rendering to work with 3D skeletal animation data

I've implemented a batch rendering technique that is described in detail here: http://www.gamedev.net/page/resources/_/technical/opengl/opengl-batch-rendering-r3900 I'd like to extend it now to ...
3
votes
1answer
545 views

I want to render some surfaces in GLSL with normal maps, and some without

I have normal mapping working in my game, but I want to only use normal mapping for some surfaces, and not others. Right now, as far as I can tell, my shader is applying an incorrect normal of (0, 0, ...
2
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1answer
264 views

How can I implement a camera like the one in RotMG?

RotMG, an MMO top-down shooter, takes on a unique 2d-3d style, and has an intriguing camera; The game is obviously 3d, not simply isometric, and if you play the game and turn on camera rotation you ...
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1answer
834 views

Triangles go missing as Z changes

I'm rendering a height map using shader-based OpenGL (3.3 to be precise). The height map data is from a grayscale bitmap (2D array of bytes). The dimension of the bitmap is 256 x 256. With this data, ...
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0answers
179 views

Dynamic VBO update possibly corrupting data?

I want to draw a line between two vertices. On a mouseclick the vertex data will change and I want to update the line to use the new values. I am using a VBO for this and it looks like the update ...
1
vote
1answer
303 views

How do I convert from rectangular to spherical coordinates?

This seems like a fairly basic and common problem. Is there a builtin way to achieve it or do I have to write the algorithm on my own? If I do, how should it work?
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1answer
127 views

Alpha blending, transparence and z-ordering

I'm making some tests with alpha blending in a projet and I don't understand something. In my tests I've done something like that and everything look good: Draw blue box first (depth test: true, ...
5
votes
4answers
408 views

OpenGL lighting appears to be clamping

I'm experiencing an odd problem where everything placed in front of my light appears black in my scene. This happens on multiple axes. I've searched the depths of the internet to find a solution, but ...
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0answers
301 views

How to properly transform vertices for a model loaded using Assimp?

When I try to load a DAE model then vertices are not placed correctly. Here's the code snippet I use to load 3D models using Assimp : aiNode* CGameObject::findNode(aiNode* rootNode, const char ...
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2answers
299 views

How can I change the value of a matrix uniform in an OpenGL vertex shader?

I'm new at OpenGL. I have a uniform transform matrix in a vertex shader file. I want to modify the matrix by individually assigning each values in the matrix. How can I do that in C++? I learned that ...
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3answers
539 views

Combine flat and smooth shading with a single model geometry

I need to be able to switch between smooth and flat shading interactively. Is there a way to do this efficiently with a single geometry? For example, smooth shading does not require duplicate ...
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0answers
108 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 ...
4
votes
1answer
1k views

For Vertex Buffer Steaming, Multiple glBufferSubData VS Orphaning?

I was learning OpenGL recently. In games, we need to update the position of game objects frequently, and they will come in & out of screen constantly. So it means in rendering we need to update ...
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1answer
153 views

Backface culling without light leaking through

I want to be able to see through walls, so to do this I used planes for the walls, and enabled backface culling. However with shadow mapping I have a lot of light leaking through: I read that using ...
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1answer
169 views

OpenGL not rendering full scene, it is a mystery [closed]

I am trying to draw a scene in the sort of style of mock vector graphics. I've helped on a 2D game before with GLSL, but I tried to keep a simple approach to this project since I'm working by myself, ...
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1answer
456 views

Uniform Block solve padding/alignment for vec3 in CPU struct

I have a struct on the CPU which I'm sending to a uniform block in my shader. After a bit frustration I finally got it to work. The problem I had was that vec3s are actually treated as 16-bytes, or in ...
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2answers
222 views

How can I efficiently render lots of 2D quads?

I have lots of 2D quads. I write their local vertex position info to a buffer (accompanied with a world transform matrix) which gets sent to the render thread. I then pass the world transform matrix ...
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vote
1answer
265 views

Android OpenGL and non premultiplied textures

As I understand it; by default all bitmaps will will get the alpha channel premultiplied in Android if loaded using BitmapFactory. My setup: I have a 32bit bitmap(.bmp) where the alpha channel has a ...
0
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1answer
899 views

wglCreateContextAttribsARB is undefined

I've just downloaded the latest headers from the OpenGL registry and included them in my project. I am attempting to create an OpenGL 3+ context. Every tutorial/resource has used ...
1
vote
1answer
305 views

Errors when loading Assimp meshes

I am experiencing some oddities when loading meshes in Assimp. Some models render perfectly, while others are complete jumbles of triangles. Some Example Images: Teapot Correct - Teapot Actual ...
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0answers
94 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 ...
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3answers
302 views

OpenGL Texture Mapping distorts image

So, I'm just trying to draw a texture to two triangles that are the same size as the viewport, but it breaks up the image and distorts it. I have tried resizing the image file and everything, but ...
2
votes
2answers
421 views

OpenGL generate hills looking vertices

I want to generate a terrain which looks like hills. Some sort of sine waves. Should be as simple as possible. But I can not figure out how. I get very scary results, which are nothing worth. I need ...
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1answer
117 views

How to fix model matrices colliding in vertex shader?

I am new to OpenGL programming and I'm writing some basic code to display a few objects onto a screen. I have a pyramid shape that I'm displaying, as well as a box shape that I am displaying. The ...
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1answer
375 views

OpenGL: I only see one square instead of a cube / giving information to vertex shader

I am new to OpenGL and tried to follow this tutorial. I use C# and OpenTK. So I translate the C++ Code from the Tutorial: My C#-Code: /* Hintergrundfarbe */ ...
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1answer
214 views

Invalid coordinates returned by glutMouseFunc()

I am using GLUT's glutMouseFunc() function to retrieve the coordinates of mouse clicks. I want to move the object on that coordinate to another coordinate. But when I click on the object the ...
5
votes
1answer
344 views

Why bother with a separate normal matrix, if there is never non-uniform scaling on the view matrix?

I am updating one of my shaders to a version of OpenGL/GLSL that doesn't automatically provide gl_NormalMatrix (for educational purposes; I'm not ripping out working code for the sake of it). ...
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0answers
29 views

Artefact in VSM as if GL_DEPTH_TEST disabled

I am trying to implement VSM and I incurred in a strange issue. I render them as follow: glUseProgram(shadowMapProgramID); glEnableVertexAttribArray(0); glBindFramebuffer(GL_FRAMEBUFFER, ...
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0answers
170 views

How to get rid of half pixel artifacts?

I've been having a bit of trouble using OpenGL to make 2D games. I am using a traditional ortho perspective with just some sprites being rendered and moved around. It all works perfectly but there is ...
0
votes
1answer
800 views

OpenGL Question about scaling 3D Object

I got some scaled cubes (1, 2.5, 1) in a 3D Space with a grounded floor with position (0, 0, 0) and scale (100, 0, 100) like in the picture. But why are the cubes scaled out from the center. I want to ...
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2answers
1k views

How can I pass a std::vector<Vector3f> to my shader?

I have a Vector3f type which has x, y, and z properties. I have a std::vector of these vertices which describe my terrain. I would like to pass these values to a vertex shader through a uniform ...
3
votes
1answer
231 views

Shader - Transmittance or Absorption

I am trying to create a transmittance or absorption shader (glsl, hlsl, cg, etc...) in realtime but I don't find any good tutorial or white paper about this subject. I only find offline rendering ...
0
votes
1answer
2k views

How do I set a background image in OpenGL/GLFW?

I'm writing a simple 2D game with C++ and OpenGL/GLFW, and my current step is to create a menu. I finished with buttons, but I think it looks a little bit boring (with only 4 buttons and a black ...
0
votes
1answer
348 views

OpenGL - Asteroids clone - shooting bullets from spaceship [duplicate]

I am having a bit of difficulty figuring out how to shoot bullets from the front of the spaceship. I can draw it to screen, but I can't properly figure out how to create bullets each time I press the ...
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0answers
202 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 ...
9
votes
1answer
530 views

In OpenGL, what is “zero state” rendering?

Recently at a job interview, I mentioned that I taught myself modern OpenGL and rendering with vertex buffer objects because my university only taught the fixed function pipeline with immediate mode ...
0
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3answers
706 views

Calculating Projectile Movement

I'm having some trouble putting together a method that will constantly move a "bullet" in the same direction accurately. Here is what I have so far public Vector3f moveFromPosition(Vector3f location, ...
0
votes
1answer
768 views

Camera Rolling when Implementing Pitch and Yaw

I am implementing a camera in opengl for an android game and am having problems getting the pitch/yaw/roll of the camera correct. I have read many tutorials on quaternions and have implemented a basic ...
0
votes
1answer
601 views

How to load and render PhysX 3.3 heightfield

I'm trying to load a PhysX 3.3 heightmap and render it with OpenGL using glm and glfw, but so far it doesn't seem to be working. I'm basing my code on the PhysX samples, and am also using FreeImage to ...
0
votes
0answers
38 views

OpenGL: What's the best way to convert a screen coordinate to a world coordinate? [duplicate]

For example, suppose I'm building a first-person shooter and the player pulls the trigger. I want to convert the screen coordinate (x, y) into a world coordinate (x, y, z) to know what they've hit. ...
0
votes
1answer
148 views

Per vertex diffuse lighting not propogating across entire model

I'm not sure how to describe this problem so I've added a picture. When I add per vertex diffuse lighting to my model (just a field of cubes for simplicity) the lighting effect applies to each ...
1
vote
1answer
2k views

What is the relationship between glVertexAttribPointer index and GLSL location?

I've been getting some strange results when trying to implement a normals buffer for the purpose of rendering lighting. It seems to be related to the indexes for glEnableVertexAttribArray, ...
7
votes
0answers
477 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 ...
2
votes
0answers
248 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
509 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
1answer
188 views

IBO interfering with VBO data?

I have a vertex and color VBO that render a plane (2 triangles) just fine. However, when I attempt to use an IBO to render the plane, the vertices are completely off. My nice square looks all crumpled ...
3
votes
1answer
327 views

How to share values between different shader programs?

I am using Unity but this might concerns all type of shaders. I would like to know if this is possible to share values between different shader pass.Let's imagine that I am computing something in the ...
0
votes
1answer
102 views

Using IBO's with color

I am trying to familiarize myself with IBO's by drawing triangles etc but I'm finding no way to get the color to apply properly. Can I not use an IBO to index the color values as well? I am having ...