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
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0answers
161 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 ...
3
votes
0answers
529 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
44 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
209 views

Skybox rendering

I am sorry if this is trivial, but I got into OpenGL just very very recently. I am trying to render skybox (with cubemaps) and this is what I have done: Created a VBO with vertices positions (36 ...
2
votes
0answers
57 views

Text rendering overlap

I'm trying to display text with a texture and font description created with BMFont in OpenGL 3.3, but whenever I display the text there is some overlap between certain characters. Here is the text at ...
2
votes
0answers
91 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 ...
2
votes
0answers
29 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 ...
2
votes
0answers
53 views

FBX Importer - Vertex Color

I imported vertex positions, indices and normals successfully in OpenGL using fbx sdk, but I just can't figure out how to import vertex colors. I tried to fetch the pointer to array of colors trough ...
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
356 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
379 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
41 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
60 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
37 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
63 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
65 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
39 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
52 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
119 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
69 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
83 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
97 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
36 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
119 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
185 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
207 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
99 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
154 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
98 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
125 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
155 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
239 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
94 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
135 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
90 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
113 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
242 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
135 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
163 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 ...
1
vote
0answers
90 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 ...
1
vote
0answers
57 views

Sampler object not changing texture filter

I am currently binding a sampler object to a texture (GL_TEXTURE12 to be specific) with glBindSampler(12, sampler); and the initial settings are very visible compared to the textures own settings. ...
1
vote
0answers
96 views

Texture not visible on particles

This is the first time I am working with particles (GL_POINTS) I am using kinematic equations and controlling their movement in vertex shader. I am following an example given in OpenGL 4.0 Cookbook ...
1
vote
0answers
233 views

Unity Pro - Shadow rendering issue

I am using Unity Pro 4.2.1f4 and I always have this sort of glitch. This is due to the shadows and the bias. Even with a low bias this is happening. I've found a thread that talks about that ...
1
vote
0answers
433 views

Geometry shader and triangle adjacency

I'm currently trying to change my project to use GL_TRIANGLE_ADJACENCY instead of GL_TRIANGLES. Following this question, I have managed to construct my index buffer fine, but when it comes to the ...
1
vote
0answers
76 views

Slick - create new texture from part of existing texture

Say I have the following image: I want to resize this texture, so I can have resizable buttons with a texture. Now, as you can't repeat a certain area of an image in OpenGL, I have to create a new ...
1
vote
0answers
501 views

How do I mix 3D skeletal animations?

I'm trying to create a 3D-model skeletal animation system for C++/Open GL. I would like to be able to mix animations by allowing animations to only affect specific bones. My game has ride-able ...
1
vote
0answers
113 views

Slick2d font rendering makes all other drawings vanish

I'm converting a java game to lwjgl and slick-utils. I've followed the slick2d examples for font loading/rendering but I found that the font shows as a solid box of color unless I add the following ...
1
vote
0answers
206 views

Rotate a point in 3D space with sine and cosine

I got my camera controlled by the mouse. Now I want a sphere to be always in the center of my view(just for testing). I tried that by assigning the sine of the Y rotation of the camera times 10 as the ...
1
vote
0answers
628 views

Creating a new GLFW window and re-using the old context causes crash

I am using GLFW 3.0.2 and when I want to switch the application to fullscreen, I create a new window and intend to use the OpenGL context of the old window so I don't have to reload all the meshes, ...
1
vote
0answers
220 views

GLX/X11 Changing the rendering resolution

I have made a simple application that creates a window with an OpenGL 4.2 context and takes user input. I have implemented making the window go fullscreen with XRandR and can change the display ...