Questions tagged [real-time]

For questions about computations subject to real-time constraints. The minimum framerate for a real-time illusion is usually considered to be around 24 frames per second. See also [interactive] for less strict constraints and [offline] for computations which will take significantly longer.

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18 votes
3 answers
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Physically based shading - ambient/indirect lighting

I implemented a physically based path tracer after studying PBRT by M. Pharr and G. Humphreys. Now I'm trying to apply physically based rendering to real time graphics using OpenGL ES (in an iPhone ...
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15 votes
1 answer
2k views

How does state of the art real time hair rendering work?

It is common knowledge that hair simulation and rendering is particularly challenging and in fact rare are the examples in games that propose believable hairs. It is pretty easy to imagine how hard it ...
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13 votes
4 answers
1k views

Projected grid water horizon detail

I'm trying to implement an ocean scene with C++ and DirectX11. Currently I have a projected grid, Gerstner waves and a basic shading. My problem is that when I aim my camera horizontally, so I can see ...
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11 votes
1 answer
4k views

Is doing multiple Gaussian blurs the same as doing one larger blur?

To make Gaussian blurring a 2d image faster, I know that you can do one axis and then the other. I'm wondering though, if I did two Gaussian blurs of size $N$, would that be the same mathematically ...
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9 votes
1 answer
2k views

Why do multiple Gaussian Blurs?

Applying multiple Gaussian blurs can result in an effect that is equivalent to a stronger Gaussian blur. For instance this question says that: Is doing multiple Gaussian blurs the same as doing one ...
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9 votes
1 answer
2k views

What is "Object Space Lighting"?

Looking at Star Swarm, a demo for the Nitrous engine, I found this little line: "Nitrous uses Object Space Lighting, the same techniques used in film, including real-time film-quality motion blur." I ...
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8 votes
3 answers
872 views

How can I create a bounding volume hierarchy for constantly moving objects?

I'd like to be able to render a large population of small independently moving objects in real time. They may move in a swarm-like manner, but their relative positions will not be coherent - their ...
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  • 5,902
8 votes
2 answers
87 views

Is there a way to achieve the look of a distant flock or shoal without full simulation?

Although simulation models like Boids give good results for bird flocks or fish shoals on a small scale, simulating every single member in real time becomes unrealistic for huge numbers. Is there a ...
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  • 5,902
8 votes
2 answers
293 views

How to create a patterned object with variable pattern density in real-time?

Assume there is some value p, calculated per-frame, that varies continuously over the surface of an object. The value of p ...
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  • 191
8 votes
2 answers
871 views

Selection of GI techniques working in real time

I'm considering topic of my thesis connected with computer graphics - I would compare some GI techniques which work completely in real time (no precomputation to lightmaps etc. and each frame ...
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  • 2,047
7 votes
2 answers
701 views

Real-time translucency effect

While rendering my scene with OpenGL, I sometimes add an overlay which contains information, settings and a few draggable items. Currently, the overlay has a slightly transparent background to make ...
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  • 1,220
7 votes
1 answer
978 views

Subsurface Scattering Without Rays?

Some games claim to use subsurface scattering but my current understanding of sss is only achieved with ray tracing. How would you sub surface scatter without ray tracing? Do some claim to use sss but ...
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7 votes
1 answer
4k views

Does PBR incur a performance penalty by design?

I am wondering if the various PBR models used in modern game engines for real time are heavier in terms of computation, that more classic approaches to rendering. Worded differently, is PBR just a ...
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7 votes
1 answer
4k views

How is motion blur implemented in modern realtime renderers?

When realtime renderers (such as 3d games) have motion blur, how is it usually implemented? I think I've heard something about needing to have motion vectors for each pixel but I'm not sure about ...
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  • 7,351
7 votes
1 answer
1k views

Confused about prefiltering environment maps (Manson 16)

I'm working my way through this paper about GGX-filtering environment maps: http://www.ppsloan.org/publications/ggx_filtering.pdf I find myself stuck on the basics. In particular, I am confused by ...
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7 votes
1 answer
758 views

How to implement a realtime 2D light renderer with fog/colored light on the GPU?

Since long ago I wanted to implement a 2D lightning algorithm based on an idea I saw on YouTube. The video is realtime, but it runs on the CPU and the resolution is pretty low. I'm curious if anyone ...
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  • 243
7 votes
1 answer
2k views

How to improve on bilateral upsampling in real time scenarios

It is a well known "standard" to use bilateral upscaling when it comes to comes to combine a low resolution target and an higher res one. I have personally noticed that using the basic algorithm (...
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6 votes
1 answer
434 views

Does prerendering actually help performance?

In PC game development, after loading models, textures, shaders, etc in a loading screen, some games will render the models once to an off screen target to make sure the driver and gpu have done all ...
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  • 7,351
6 votes
1 answer
172 views

fix over exposure in importance sampling in screen space reflections

I am having my first encounter with the rendering of indirect reflections in the form of screen space reflections in a game engine, but i am struggling to get correct looking results. (patterns arise ...
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6 votes
0 answers
234 views

How is Ambient Occlusion calculated in "Deep Screen Space"?

The paper (http://resources.mpi-inf.mpg.de/DeepScreenSpace/) just says that "The ambient occlusion contribution of a surfel to a pixel [..] as well as the influence radius [..] are computed ...
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  • 143
5 votes
2 answers
4k views

What are the current open problems in Computer Graphics?

I did a quick investigation about the topic but there doesn't seem a decent resource to find related problems without digging into latest CG papers (unlike CS problems you can easily find a Wikipedia ...
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  • 233
5 votes
2 answers
5k 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 ...
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  • 7,351
5 votes
2 answers
3k views

How to reduce the number of draw calls when rendering one object multiple times?

Especially when rendering particle effects, the same object needs to be rendered several times with slightly modified properties. But these changes are often limited to properties like pose or ...
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  • 1,220
5 votes
1 answer
1k views

Benefits of Clustered Shading vs Tiled Shading?

The Unity Engine manual page Best Practice: Setting up the Lighting Pipeline has a section "Render pipelines" with an illustration of Tile Rendering and Cluster Rendering: The section then mentions:...
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  • 1,689
5 votes
1 answer
151 views

Correct post-displacement normal calculation (Y-component and epsilon)

I often use a 2D Perlin noise texture to displace a grid in the vertex shader (e.g. terrain, ocean). However, every time I google the method to calculate post-displacement normals there is a slight ...
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5 votes
1 answer
222 views

Questions about Preconditioning Conjugate Gradient method in Baraff & Witkin 98?

I encountered some problems when implementing the cloth simulation algorithm from Baraff & Witkin 98's Large Steps in Cloth Simulation. Baraff & Witkin 98 Consider the cloth as a particle ...
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5 votes
1 answer
582 views

Methods for grid traversal in a glsl pixel shader?

I'm working on a shadertoy "snake" game, using the new multi pass rendering abilities to save game state between frames. I'm using raytracing to render the board (an AABB), and am planning on using ...
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  • 7,351
5 votes
0 answers
229 views

Why is Forward Rendering/Shading named this way?

Forward rendering is the 'classic' approach to the rendering pipeline. Nowadays it is mostly replaced by a more flexible, deferred rendering approach. I did some research and had trouble finding ...
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  • 151
4 votes
1 answer
940 views

How does directional Gaussian blurring work?

In image editing software, you often have the ability to do a directional blur where you can choose and angle and a magnitude of a blur. How does this actually work in practice with Gaussian blurring?...
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  • 7,351
4 votes
1 answer
399 views

What is better to use for real-time computing Mesh - Plane intersection points, GPU or CPU?

I want to write plugin (library) for Unity3d (it doesn't matter which framework I will choose for this, question is ), for cutting arbitrary mesh with plane (for simplicity it will be plane for ...
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4 votes
3 answers
523 views

Texture coordinates projection

I have some classic texture coordinates and as a normal behaviour they follow the mesh's transformations. I am trying to use the same texture coordinates behaviour but without being affected by the ...
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  • 1,169
4 votes
0 answers
64 views

Is it possible to create a forced focus with a dual layer of images in order to Avoid eye strain with Virtual and Augmented Reality?

Would eye tracking allow for the alignment of a dual layered image (a google glass like device and a screen or projection) to provide a way to force the focus of the eyes into to a real life ...
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  • 41
3 votes
2 answers
1k views

Phong: Real-time rendering of Metal and Plastic Materials

Using a shader that works like Phong, what would be the difference between painted Metal and plastic? I seem to remember reading in books years ago, that I no longer have access to, the following: ...
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  • 133
3 votes
1 answer
341 views

Importance Sampling in Unreal Engine Formula Derivation (Irradiance term)

I am currently trying to understand IBL in Unreal Engine, and there are so much things that I don't understand about the formula. Unreal approximate the specular term of shading equation by doing ...
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  • 473
3 votes
1 answer
703 views

Advantages of spherical harmonics over baked vertex lighting?

My question is about spherical harmonic lightning, in the context of computing the coefficients with an expensive GI algorithm and passing them to the vertex shader Another way is to just use an ...
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3 votes
1 answer
69 views

In what order to apply lighting and translucency?

I'm making a game that is supposed to like like a early 90s 3D game, so i'm rendering in software on an 8-bit indexed bitmap, using lookup tables for translucency and lighting. Now I have to draw a ...
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2 votes
1 answer
86 views

How can I make a graphics demo without a frame buffer?

I am programming a microcontroller - a tiny 8 bit computer that has about 100Mhz - 300Mhz CPU clock speed and 64K application RAM (actually ROM), but only a tiny amount of RAM (6K) - nowhere near ...
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2 votes
1 answer
250 views

Real time image based lighting for arbitrary BRDFs coordinate alignment

I was trying to understand how real-time illumination happens with image-based lighting. I understood that importance of representing the Environment Map and BRDF in spherical harmonics. Because ...
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2 votes
1 answer
207 views

light probe (for global illumination) placement techniques?

I'm learning light probes used for dynamic global illumination. I have a question regarding the placement of light probes, as based on most of the pictures I have seen, they seem to be placed ...
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  • 121
2 votes
1 answer
576 views

Downscaling texture via mipmap [DirectX 11]

I am implementing a post-processing effect in my DirectX 11 pet renderer. The post-processing pass is implemented by rendering a full-screen quad covered with texture containing original rendered ...
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  • 1,377
2 votes
0 answers
48 views

Accelerating dose calculation for a radiation therapy planning system

During radiation therapy, appropriate radiation is fired from various positions around the patient. Radiation therapy planning determines the values of the radiation at various positions. This ...
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  • 121
2 votes
0 answers
60 views

Is this the correct interpretation of the separable SSS artistic model?

I'm trying to understand the separable subsurface scattering algorithm, but I'm a little confused on what the parameters mean from a notation and implementation standpoint, particularly for the ...
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  • 1,323
2 votes
0 answers
264 views

Projecting light shapes

I am wondering how professional light visualizer software (like Capture Argo - WYSIWYG - Realizzer - LightConverse) project the lights on the objects (like stage, floor, people), even projecting the ...
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1 vote
1 answer
41 views

What can be reduce in peripheral circle and increase in foveated cirle?

Foveated rendering, is definitely one of the newest fields of real-time graphics rendering. The main goal of foveated rendering is reducing rendering cost to increase frame-rate without perception ...
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  • 113
1 vote
1 answer
618 views

What framework shoud I use to implement the RAISR upscaling algorithm on the GPU?

I recently ran across the paper RAISR: Rapid and Accurate Image Super Resolution and thought it seemed like an interesting technique for scaling up images. However, I haven't seen any implementation ...
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1 vote
1 answer
1k views

Which technique is fast to generate real-time reflections?

I want to know about some technique with which i can generate nice reflections on the surface. I know one conventional technique where we invert an object and render it and blend it with the floor but ...
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1 vote
2 answers
82 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 ...
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1 vote
1 answer
61 views

Consistent animation speed across systems

I recently noticed that in all games, no matter what system you play on or what specs you have, your character will always move at the same speed even if there is no frame rate limit. I was wondering ...
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1 vote
1 answer
578 views

Radiosity normal map light baking

I'm trying to implement radiosity normal maps from the old Valve paper: Half-Life® 2 / Valve Source™ Shading.pdf | valvesoftware.com I've tried generating the light maps using Vray and 3dStudio max, ...
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1 vote
0 answers
91 views

Time Interval Ray Tracing performance

I found a very nice paper regarding Time Interval Ray Tracing for Motion Blur published in 2017. That was before RTX GPUs were on the market. I have a few questions about an optimal implementation and ...
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