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1answer
146 views

maximal convex patching in Computer graphics

Given a 3D object in Computer graphics, whose surface is represented as a 3D triangular mesh (mesh of 3D triangle objects), I need to find the maximum continual Convex patches on the surface of the ...
5
votes
1answer
101 views

Can I run polygon insetting on the surface of a mesh?

I have a set of closed loops on the surface of a non-self-intersecting triangle mesh, and I need to create inset versions of them on the surface of the mesh. In other words, I want to generate a ...
10
votes
2answers
6k views

Cause of shadow acne

I know how shadow mapping works but I am not getting the cause of shadow acne! Can anyone tell me cause of shadow acne in a simple way and how is it related to depth map resolution?
6
votes
1answer
264 views

Should not specular reflection on a rough surface be similar to diffuse reflection?

Different BRDFs are usually used to compute diffuse and specular reflection. Some of the most often used include for example the Lambert BRDF for diffuse reflection and the Cook-Torrance BRDF for ...
5
votes
0answers
664 views

Drawing to framebuffer texture - texture then split in half

I am doing exercises from the OpenGL SuperBible 6th Ed. I have managed to set up rendering into a framebuffer texture and then rendering from that texture to a cube. But for some reason, when the ...
4
votes
0answers
184 views

OpenSCAD Hull/Minkowski function by hand?

I am trying to model an organic object using OpenSCAD. However this will need to be ported over to older software. This restricts the primitives I can use (only cone, cylinder, torus, sphere and cubes)...
5
votes
1answer
95 views

gamma transform in webGLSL: when already done or yet to be done?

Color spaces issues are such a pain, especially when you create color data at the middle of the chain, and a pile of libs and apps separate this to the display... Here I only worry about gamma ...
4
votes
1answer
876 views

Guidance with Sphere-Map calculation in GLSL

I'm trying to achieve the same effect in OpenGL/GLSL as what Blender does when you add a texture, set to "Reflection" This ultimately is a way to fake specularity, or "metallicness" if I get it right....
5
votes
1answer
218 views

Converting raster shape/blob into displacement map

I am a beginner in digital image processing and computer graphics. I would like to program a similar behavior than the Shadermap 3 normal editor (displacement layer more specifically). As shown in ...
4
votes
2answers
504 views

Clearing but not drawing objects

I was trying to draw a plane and cubes in a framebuffer but nothing is drawing in that framebuffer besides clearing it with a color. Here's the code... ...
1
vote
1answer
80 views

Separating photos from other images algorithmically? [closed]

Can an algorithm be derived to classify digital images according to how they were generated, i.e. the classes would be: Real-world photograph captured with an actual camera. A Computer-Generated ...
6
votes
1answer
877 views

Calculating intersection of polyline and line

I have a convoluted polyline composed of vertices and straight segments and a separate point that is independent of the polyline. I am trying draw a straight new line from the point at a given angle ...
9
votes
0answers
254 views

Choosing width of data for signed distance field texture

A signed distance field texture is a technique where you store the distance from a pixel to the surface of a shape within the color information for that pixel, allowing almost vector graphics quality ...
5
votes
2answers
4k views

How does vsync affect fps exactly when not at full vsync fps?

I know that if you turn of vsync, it synchronizes rendering with the vertical redraw cycle to prevent tearing, and that doing so caps your rendering rate (FPS) at the monitor refresh rate, which is ...
4
votes
1answer
92 views

library / tool for implementing algorithms

I'm new to graphics and want to implement algorithms like dda,scan-line, clipping,etc. I'm confused which library to use. OpenGl, graphics in turbo c,or any other. Please suggest.
1
vote
1answer
2k views

Creating vector shapes using only C++ [closed]

I've been researching for quite a while and I couldn't find any explanation or at least a how to create a vector graphic application (specifically in windows) where I can create a 3D vector shape, say ...
4
votes
1answer
643 views

Modern Screen Space Ambient Occlusion Techniques

Down the road, I'm planning to implement one or another GPU based ambient occlusion technique. My goal will be to approximate a physically based offline renderer, so I was pretty happy when Wikipedia ...
1
vote
2answers
73 views

live music visualisation [closed]

Does anyone out there know of any software for developing real time visualisations and analysis of real time sound, say using a mike? I've found a few but none allow the user to build up their own ...
3
votes
0answers
380 views

Normal mapping for planar reflections

Ok guys, tricky one! I'm trying to modify this Unity script + shader to include normal mapping. The tl;dr is, it uses a single texture rather than a cubemap as it is only for reflecting in a planar ...
6
votes
1answer
536 views

SSAO artefacts on iPhone (OpenGL ES)

I've never written shaders before, and now I'm trying to implement SSAO with SceneKit on OS X and iOS. I'm trying different SSAO shaders that I find, e.g. from Three.js, this one, and this one. On OS ...
11
votes
1answer
3k views

Loop performance in a shader

I am wondering what's the best way to integrate a dynamic loop function in a shader? First, it seems that dynamic arrays are not possible. So, is it better to create a maximum size array and only ...
4
votes
0answers
54 views

Making surface with common parametrization from bunch of other surfaces

I have bunch of surfaces, like in these two images: Currently to make single surface with common parametrization I sample points uniformly from all source surfaces, and fit single NURBS surface from ...
1
vote
1answer
81 views

Get data from javascript

There is an web-interface that load geometric models and show it inside the bounding volume. WebGL is used to generate it. So far no scene graph technique is used to organize the elements in the scene....
8
votes
1answer
271 views

Moving each point of a surface in direction of corresponding normal

So let assume that I have some convex smooth and unclosed surface. I'm moving each point of it in a normal direction by some constant factor (This factor is same for all points on surface). Can I ...
2
votes
1answer
387 views

A question about derivation in oblique view frustum

Problem Description: Reference: Oblique View Frustum Depth Projection and Clipping "Mathematics for 3D Game Programming and Computer Graphics" 3rd edition, chapter 5.6. M is the original projection ...
4
votes
2answers
139 views

intersection between line segments - narrowed precondition

I believe that the issue may already have been discussed here. I want to find if two line segments does intersect and if they do then find and store and intesection points. Now it is already confirmed ...
7
votes
1answer
454 views

How to invert an affine matrix with small values?

I'm using an affine transformation matrix to transform 2D coordinates from screen (magnitude 10e3) to small parts of fractal sets (magnitude as little as 10e-15). I also need to map the other way ...
4
votes
1answer
106 views

Seamlessly transitioning between nearby environment maps

I'm wondering what is the best way to achieve an effect like here: https://matterport.com/try/ when the camera is traveling between points in space. Apart from simple color crossfade there seems to ...
1
vote
0answers
200 views

Free 3D Scene Simulation Framework [closed]

I want to visualize a scene with simple shapes (e.g. boxes, pyramides, etc.) and I am looking for a tool or framework in C/C++ to do this. Focus of the application is to parameterize the relative ...
2
votes
0answers
464 views

Template matching subpixel accuracy

I use template matching to detect a specific pattern in image.The shift determined is very shaky. Currently I apply it to R,G,B channel separately and average the result to obtain float values.Please, ...
8
votes
1answer
339 views

Do modern GPUs contain barrel shifters?

I'm aware that most modern GPUs, although designed for floating point, are more or less equivalent in integer performance these days, with a few caveats like the lack of a fused multiply add. I'm not ...
8
votes
1answer
173 views

Conserving Mass in Liquid Simulation

I am trying to implement a 2D version of Foster and Fedkiw's paper, "Practical Animation of Liquids" here: http://physbam.stanford.edu/~fedkiw/papers/stanford2001-02.pdf Mostly everything works, ...
20
votes
1answer
3k views

Anti-aliasing / Filtering in Ray Tracing

In ray tracing / path tracing, one of the simplest way to anti-alias the image is to supersample the pixel values and average the results. IE. instead of shooting every sample through the center of ...
3
votes
1answer
68 views

vertical or horizontal line test

I have a line segment defined by two coordinate values and I need to check if the line segment is parallel to the x-axis or y-axis. I believe that it is not that difficult to find. When it comes to ...
4
votes
1answer
280 views

SVG opengl implementation - strokes overlap on transparency

I am trying to implement svg rendering by opengl using meshes. In paths with opacity less than 1, the color of overlapping strokes add up. But it should be like this the opengl calls are: ...
15
votes
1answer
10k views

Get vector length with GLM

I am quite confused over how GLM library is behaving or I am using it improperly. glm::vec2 testVec(6,-4); float len = testVec.length(); I get the value ...
9
votes
1answer
300 views

Map a texture onto a hyperbolic triangle

I've been stuck on how to approach this for a while, so any suggestions would be gratefully appreciated! I want to map a texture in the form of a lower right euclidean triangle to a hyperbolic ...
7
votes
2answers
732 views

Raytracing Problem - Casting Shadows

So I was tasked to create a model of the Cornell Box. I've managed to do everything up until casting shadows, in which case some shadows are cast when there should not be any. Here are pictures of ...
11
votes
1answer
664 views

Compensation for energy loss in single-scattering microfacet BSDF models

Single-scattering microfacet-based surface models like the original Torrance-Sparrow BRDF or derived models like the BSDF for rough dielectric surfaces by Walter et al. neglect inter-reflection of ...
1
vote
1answer
66 views

How to test if one object A intersects and is therefore partly or wholly inside object B

I have the world point positions of two objects, and would like to test if there is an intersection between the two objects from this information. What methods can I use to test this, especially at ...
4
votes
1answer
347 views

Test if a point is on a line segment

I have a line segment defined by two end points. And I have another randomly chosen third point and I want to find out if the third point is on the line segment or not. By "On the line segment", I ...
10
votes
1answer
945 views

Is Jump Flood Algorithm Separable?

JFA (the algorithm described here: http://www.comp.nus.edu.sg/~tants/jfa/i3d06.pdf) can be used to get an approximation of a Voronoi diagram, or a distance transform. It does so in logarithmic time ...
4
votes
1answer
347 views

Frustum - problem with z dimension

I'm beginner in OpenGL and I stumbled into a problem. I'm in OpenGL 2.1 for the time being, if that's of any help. I set my Frustum as such: ...
1
vote
3answers
200 views

Trouble Finding Simple 2D DirecX11/HLSL Issue

Some possible things that might be the issue and could be explained by someone who is knowledgeable Order of my indices, In all I've read, your array of indices for a triangle list is just clockwise ...
3
votes
1answer
642 views

Triangulated model rasterization: light-weight Python library

I have a 3D model, which consists of ~50 thousand vertices and 100 thousand triangles. Format is: there's array of vertices' coordinates and array of triangles, which has numbers of vertices (e.g., [1,...
9
votes
3answers
2k views

Ordering a set of unorganized points along a curve

I have a set of 3D points (which I recover from a library that performs the tessellation of a solid body) that belong to a curve (i.e., an edge of the solid). That means that the curve surely passes ...
2
votes
1answer
120 views

How can I use multiple texturing with shadow mapping?

So, recently I followed this tutorial about shadow mapping, but in the tutorial it doesn't texture the object.. When I try to add a texture, it's distorted by the ...
4
votes
2answers
718 views

Why map Hammersley 2D set's (u,v) to sphere's (θ, φ) coordinates (and not to (φ, θ) )?

As explained in Holger Dammetz page Hammersley Points on the Hemisphere, the 2D coordinates (u,v) are usually mapped to the spherical coordinates (θ, φ). As a result, the coordinate "uniformly ...
8
votes
3answers
404 views

Color space of MERL BRDF database?

I know that by now it might be considered as a kind of sad recurrent joke, but by chance, does anyone here has the least information about the colorspace of RGB values in the MERL BRDF measurement ...
6
votes
1answer
179 views

Volume Rendering in simple words

I am looking for a explanation about volume rendering in simple words, a step by step kind of, like ray tracing: for every pixel in the screen plane, trace a ray starting from the eye point to ...

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