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• By elect
Hi,
ok, so, we are having problems with our current mirror reflection implementation.
At the moment we are doing it very simple, so for the i-th frame, we calculate the reflection vectors given the viewPoint and some predefined points on the mirror surface (position and normal).
Then, using the least squared algorithm, we find the point that has the minimum distance from all these reflections vectors. This is going to be our virtual viewPoint (with the right orientation).
After that, we render offscreen to a texture by setting the OpenGL camera on the virtual viewPoint.
And finally we use the rendered texture on the mirror surface.
So far this has always been fine, but now we are having some more strong constraints on accuracy.
What are our best options given that:
- we have a dynamic scene, the mirror and parts of the scene can change continuously from frame to frame
- we have about 3k points (with normals) per mirror, calculated offline using some cad program (such as Catia)
- all the mirror are always perfectly spherical (with different radius vertically and horizontally) and they are always convex
- a scene can have up to 10 mirror
- it should be fast enough also for vr (Htc Vive) on fastest gpus (only desktops)

Looking around, some papers talk about calculating some caustic surface derivation offline, but I don't know if this suits my case
Also, another paper, used some acceleration structures to detect the intersection between the reflection vectors and the scene, and then adjust the corresponding texture coordinate. This looks the most accurate but also very heavy from a computational point of view.

Other than that, I couldn't find anything updated/exhaustive around, can you help me?

• Hello all,
I am currently working on a game engine for use with my game development that I would like to be as flexible as possible.  As such the exact requirements for how things should work can't be nailed down to a specific implementation and I am looking for, at least now, a default good average case scenario design.
Here is what I have implemented:
Deferred rendering using OpenGL Arbitrary number of lights and shadow mapping Each rendered object, as defined by a set of geometry, textures, animation data, and a model matrix is rendered with its own draw call Skeletal animations implemented on the GPU.   Model matrix transformation implemented on the GPU Frustum and octree culling for optimization Here are my questions and concerns:
Doing the skeletal animation on the GPU, currently, requires doing the skinning for each object multiple times per frame: once for the initial geometry rendering and once for the shadow map rendering for each light for which it is not culled.  This seems very inefficient.  Is there a way to do skeletal animation on the GPU only once across these render calls? Without doing the model matrix transformation on the CPU, I fail to see how I can easily batch objects with the same textures and shaders in a single draw call without passing a ton of matrix data to the GPU (an array of model matrices then an index for each vertex into that array for transformation purposes?) If I do the matrix transformations on the CPU, It seems I can't really do the skinning on the GPU as the pre-transformed vertexes will wreck havoc with the calculations, so this seems not viable unless I am missing something Overall it seems like simplest solution is to just do all of the vertex manipulation on the CPU and pass the pre-transformed data to the GPU, using vertex shaders that do basically nothing.  This doesn't seem the most efficient use of the graphics hardware, but could potentially reduce the number of draw calls needed.

Really, I am looking for some advice on how to proceed with this, how something like this is typically handled.  Are the multiple draw calls and skinning calculations not a huge deal?  I would LIKE to save as much of the CPU's time per frame so it can be tasked with other things, as to keep CPU resources open to the implementation of the engine.  However, that becomes a moot point if the GPU becomes a bottleneck.

• Hello!
I would like to introduce Diligent Engine, a project that I've been recently working on. Diligent Engine is a light-weight cross-platform abstraction layer between the application and the platform-specific graphics API. Its main goal is to take advantages of the next-generation APIs such as Direct3D12 and Vulkan, but at the same time provide support for older platforms via Direct3D11, OpenGL and OpenGLES. Diligent Engine exposes common front-end for all supported platforms and provides interoperability with underlying native API. Shader source code converter allows shaders authored in HLSL to be translated to GLSL and used on all platforms. Diligent Engine supports integration with Unity and is designed to be used as a graphics subsystem in a standalone game engine, Unity native plugin or any other 3D application. It is distributed under Apache 2.0 license and is free to use. Full source code is available for download on GitHub.
Features:
True cross-platform Exact same client code for all supported platforms and rendering backends No #if defined(_WIN32) ... #elif defined(LINUX) ... #elif defined(ANDROID) ... No #if defined(D3D11) ... #elif defined(D3D12) ... #elif defined(OPENGL) ... Exact same HLSL shaders run on all platforms and all backends Modular design Components are clearly separated logically and physically and can be used as needed Only take what you need for your project (do not want to keep samples and tutorials in your codebase? Simply remove Samples submodule. Only need core functionality? Use only Core submodule) No 15000 lines-of-code files Clear object-based interface No global states Key graphics features: Automatic shader resource binding designed to leverage the next-generation rendering APIs Multithreaded command buffer generation 50,000 draw calls at 300 fps with D3D12 backend Descriptor, memory and resource state management Modern c++ features to make code fast and reliable The following platforms and low-level APIs are currently supported:
Windows Desktop: Direct3D11, Direct3D12, OpenGL Universal Windows: Direct3D11, Direct3D12 Linux: OpenGL Android: OpenGLES MacOS: OpenGL iOS: OpenGLES API Basics
Initialization
The engine can perform initialization of the API or attach to already existing D3D11/D3D12 device or OpenGL/GLES context. For instance, the following code shows how the engine can be initialized in D3D12 mode:
#include "RenderDeviceFactoryD3D12.h" using namespace Diligent; // ...  GetEngineFactoryD3D12Type GetEngineFactoryD3D12 = nullptr; // Load the dll and import GetEngineFactoryD3D12() function LoadGraphicsEngineD3D12(GetEngineFactoryD3D12); auto *pFactoryD3D11 = GetEngineFactoryD3D12(); EngineD3D12Attribs EngD3D12Attribs; EngD3D12Attribs.CPUDescriptorHeapAllocationSize[0] = 1024; EngD3D12Attribs.CPUDescriptorHeapAllocationSize[1] = 32; EngD3D12Attribs.CPUDescriptorHeapAllocationSize[2] = 16; EngD3D12Attribs.CPUDescriptorHeapAllocationSize[3] = 16; EngD3D12Attribs.NumCommandsToFlushCmdList = 64; RefCntAutoPtr<IRenderDevice> pRenderDevice; RefCntAutoPtr<IDeviceContext> pImmediateContext; SwapChainDesc SwapChainDesc; RefCntAutoPtr<ISwapChain> pSwapChain; pFactoryD3D11->CreateDeviceAndContextsD3D12( EngD3D12Attribs, &pRenderDevice, &pImmediateContext, 0 ); pFactoryD3D11->CreateSwapChainD3D12( pRenderDevice, pImmediateContext, SwapChainDesc, hWnd, &pSwapChain ); Creating Resources
Device resources are created by the render device. The two main resource types are buffers, which represent linear memory, and textures, which use memory layouts optimized for fast filtering. To create a buffer, you need to populate BufferDesc structure and call IRenderDevice::CreateBuffer(). The following code creates a uniform (constant) buffer:
BufferDesc BuffDesc; BufferDesc.Name = "Uniform buffer"; BuffDesc.BindFlags = BIND_UNIFORM_BUFFER; BuffDesc.Usage = USAGE_DYNAMIC; BuffDesc.uiSizeInBytes = sizeof(ShaderConstants); BuffDesc.CPUAccessFlags = CPU_ACCESS_WRITE; m_pDevice->CreateBuffer( BuffDesc, BufferData(), &m_pConstantBuffer ); Similar, to create a texture, populate TextureDesc structure and call IRenderDevice::CreateTexture() as in the following example:
TextureDesc TexDesc; TexDesc.Name = "My texture 2D"; TexDesc.Type = TEXTURE_TYPE_2D; TexDesc.Width = 1024; TexDesc.Height = 1024; TexDesc.Format = TEX_FORMAT_RGBA8_UNORM; TexDesc.Usage = USAGE_DEFAULT; TexDesc.BindFlags = BIND_SHADER_RESOURCE | BIND_RENDER_TARGET | BIND_UNORDERED_ACCESS; TexDesc.Name = "Sample 2D Texture"; m_pRenderDevice->CreateTexture( TexDesc, TextureData(), &m_pTestTex ); Initializing Pipeline State
Diligent Engine follows Direct3D12 style to configure the graphics/compute pipeline. One big Pipelines State Object (PSO) encompasses all required states (all shader stages, input layout description, depth stencil, rasterizer and blend state descriptions etc.)
To create a shader, populate ShaderCreationAttribs structure. An important member is ShaderCreationAttribs::SourceLanguage. The following are valid values for this member:
SHADER_SOURCE_LANGUAGE_DEFAULT  - The shader source format matches the underlying graphics API: HLSL for D3D11 or D3D12 mode, and GLSL for OpenGL and OpenGLES modes. SHADER_SOURCE_LANGUAGE_HLSL  - The shader source is in HLSL. For OpenGL and OpenGLES modes, the source code will be converted to GLSL. See shader converter for details. SHADER_SOURCE_LANGUAGE_GLSL  - The shader source is in GLSL. There is currently no GLSL to HLSL converter. To allow grouping of resources based on the frequency of expected change, Diligent Engine introduces classification of shader variables:
Static variables (SHADER_VARIABLE_TYPE_STATIC) are variables that are expected to be set only once. They may not be changed once a resource is bound to the variable. Such variables are intended to hold global constants such as camera attributes or global light attributes constant buffers. Mutable variables (SHADER_VARIABLE_TYPE_MUTABLE) define resources that are expected to change on a per-material frequency. Examples may include diffuse textures, normal maps etc. Dynamic variables (SHADER_VARIABLE_TYPE_DYNAMIC) are expected to change frequently and randomly. This post describes the resource binding model in Diligent Engine.
The following is an example of shader initialization:
To create a pipeline state object, define instance of PipelineStateDesc structure. The structure defines the pipeline specifics such as if the pipeline is a compute pipeline, number and format of render targets as well as depth-stencil format:
// This is a graphics pipeline PSODesc.IsComputePipeline = false; PSODesc.GraphicsPipeline.NumRenderTargets = 1; PSODesc.GraphicsPipeline.RTVFormats[0] = TEX_FORMAT_RGBA8_UNORM_SRGB; PSODesc.GraphicsPipeline.DSVFormat = TEX_FORMAT_D32_FLOAT; The structure also defines depth-stencil, rasterizer, blend state, input layout and other parameters. For instance, rasterizer state can be defined as in the code snippet below:
// Init rasterizer state RasterizerStateDesc &RasterizerDesc = PSODesc.GraphicsPipeline.RasterizerDesc; RasterizerDesc.FillMode = FILL_MODE_SOLID; RasterizerDesc.CullMode = CULL_MODE_NONE; RasterizerDesc.FrontCounterClockwise = True; RasterizerDesc.ScissorEnable = True; //RSDesc.MultisampleEnable = false; // do not allow msaa (fonts would be degraded) RasterizerDesc.AntialiasedLineEnable = False; When all fields are populated, call IRenderDevice::CreatePipelineState() to create the PSO:
Shader resource binding in Diligent Engine is based on grouping variables in 3 different groups (static, mutable and dynamic). Static variables are variables that are expected to be set only once. They may not be changed once a resource is bound to the variable. Such variables are intended to hold global constants such as camera attributes or global light attributes constant buffers. They are bound directly to the shader object:

m_pPSO->CreateShaderResourceBinding(&m_pSRB); Dynamic and mutable resources are then bound through SRB object:
m_pSRB->GetVariable(SHADER_TYPE_VERTEX, "tex2DDiffuse")->Set(pDiffuseTexSRV); m_pSRB->GetVariable(SHADER_TYPE_VERTEX, "cbRandomAttribs")->Set(pRandomAttrsCB); The difference between mutable and dynamic resources is that mutable ones can only be set once for every instance of a shader resource binding. Dynamic resources can be set multiple times. It is important to properly set the variable type as this may affect performance. Static variables are generally most efficient, followed by mutable. Dynamic variables are most expensive from performance point of view. This post explains shader resource binding in more details.
Setting the Pipeline State and Invoking Draw Command
Before any draw command can be invoked, all required vertex and index buffers as well as the pipeline state should be bound to the device context:
// Clear render target const float zero[4] = {0, 0, 0, 0}; m_pContext->ClearRenderTarget(nullptr, zero); // Set vertex and index buffers IBuffer *buffer[] = {m_pVertexBuffer}; Uint32 offsets[] = {0}; Uint32 strides[] = {sizeof(MyVertex)}; m_pContext->SetVertexBuffers(0, 1, buffer, strides, offsets, SET_VERTEX_BUFFERS_FLAG_RESET); m_pContext->SetIndexBuffer(m_pIndexBuffer, 0); m_pContext->SetPipelineState(m_pPSO); Also, all shader resources must be committed to the device context:
m_pContext->CommitShaderResources(m_pSRB, COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES); When all required states and resources are bound, IDeviceContext::Draw() can be used to execute draw command or IDeviceContext::DispatchCompute() can be used to execute compute command. Note that for a draw command, graphics pipeline must be bound, and for dispatch command, compute pipeline must be bound. Draw() takes DrawAttribs structure as an argument. The structure members define all attributes required to perform the command (primitive topology, number of vertices or indices, if draw call is indexed or not, if draw call is instanced or not, if draw call is indirect or not, etc.). For example:
DrawAttribs attrs; attrs.IsIndexed = true; attrs.IndexType = VT_UINT16; attrs.NumIndices = 36; attrs.Topology = PRIMITIVE_TOPOLOGY_TRIANGLE_LIST; pContext->Draw(attrs); Tutorials and Samples
The GitHub repository contains a number of tutorials and sample applications that demonstrate the API usage.

AntTweakBar sample demonstrates how to use AntTweakBar library to create simple user interface.

Atmospheric scattering sample is a more advanced example. It demonstrates how Diligent Engine can be used to implement various rendering tasks: loading textures from files, using complex shaders, rendering to textures, using compute shaders and unordered access views, etc.

The repository includes Asteroids performance benchmark based on this demo developed by Intel. It renders 50,000 unique textured asteroids and lets compare performance of D3D11 and D3D12 implementations. Every asteroid is a combination of one of 1000 unique meshes and one of 10 unique textures.

Integration with Unity
Diligent Engine supports integration with Unity through Unity low-level native plugin interface. The engine relies on Native API Interoperability to attach to the graphics API initialized by Unity. After Diligent Engine device and context are created, they can be used us usual to create resources and issue rendering commands. GhostCubePlugin shows an example how Diligent Engine can be used to render a ghost cube only visible as a reflection in a mirror.

• By Yxjmir
I'm trying to load data from a .gltf file into a struct to use to load a .bin file. I don't think there is a problem with how the vertex positions are loaded, but with the indices. This is what I get when drawing with glDrawArrays(GL_LINES, ...):

Also, using glDrawElements gives a similar result. Since it looks like its drawing triangles using the wrong vertices for each face, I'm assuming it needs an index buffer/element buffer. (I'm not sure why there is a line going through part of it, it doesn't look like it belongs to a side, re-exported it without texture coordinates checked, and its not there)
I'm using jsoncpp to load the GLTF file, its format is based on JSON. Here is the gltf struct I'm using, and how I parse the file:
glBindVertexArray(g_pGame->m_VAO);
glDrawElements(GL_LINES, g_pGame->m_indices.size(), GL_UNSIGNED_BYTE, (void*)0); // Only shows with GL_UNSIGNED_BYTE
glDrawArrays(GL_LINES, 0, g_pGame->m_vertexCount);
So, I'm asking what type should I use for the indices? it doesn't seem to be unsigned short, which is what I selected with the Khronos Group Exporter for blender. Also, am I reading part or all of the .bin file wrong?
Test.gltf
Test.bin

• That means how do I use base DirectX or OpenGL api's to make a physics based destruction simulation?
Will it be just smart rendering or something else is required?

# OpenGL Raytracing for dummies

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## Recommended Posts

Fellow programmers, With all that talking about Global Illumination, guys like Vlad woke up my interrest to write a (simple) raytracer. I believe raytracing will take over some day, so I'd better be prepared :) My learning curve is ussually pretty long, and I don't have much free time (especially not with my other "normally rendered" hobby project), so the sooner I start, the better. Besides, I think its fun and very refreshing to do something 'different'. I know the basic principles of ray-tracing, and especially the (dis)advantages when comparing to the rasterization methods we use every day. But I wouldn't know how/where to start with RT. So, I made a list of questions. I must add that I'm looking for practical (read fast) implementations. I'm not looking for the cutting-edge or highest quality graphics. Let's say I'd like to program games, not graphics allone. In other words, the technique should be able to produce realtime results in the next ~4 years, suitable for a game. 1.- So... which technique is the most practical(fastest) for realtime/games? I've read a little bit ray-tracing and photon mapping. Are these 2 different things? 2.- Lights. From what I read so far I shoot rays from my eyes. They collide somewhere, but at that point we don't know yet if that point is litten yes/no. How to find that out? Shoot a ray from that point to all possible lightsources? And how about indirect lighting then? I could do it reversed, starting at the lights, but then there is not telling if its rays ever reach the camera. 3.- Does a RT still need OpenGL/DirectX/shaders ? I guess you can combine both (for example, render a scene normally, and add special effects such as GI/Caustics/Reflections via RT). What is used in common?' I can imagine a shader is used on top to smooth/blur the somewhat noisy results of a RT produced screen. 4.- How does RT access textures? I suppose you can use diffuse textures and normal/specular/gloss Maps just as well. You just access them via the RAM and eventually write your own filtering method? If that is true, it would mean you have lots of 'texture memory' and can directly change a texture as well (draw on it for example). 5.- Ray tracing has lots to do with collision detection. Now this is the part where I'm getting scared since my math is not very well. I wrote octrees and several collision detection functions, but I can't imagine them fast enough to run millions of rays... I mean 800x600 pixels = 480.000 rays. And that number multiplies if I want reflections/refractions(and we most certainly want that!). Do I underestemate the power of the CPU('s), do I count way too much rays, or is it indeed true that VERY OPTIMIZED algorithms are required here? 6.- Overall, how difficult is writing a RT? Writing a basic OpenGL program is simple, but implementating billions of effects with all kind of crazy tricks (FBO's, shaders for each and every material type, alpha blending, (cascaded) shadowMaps, mirroring, cubeMaps, probes, @#%$#@$) is difficult as well. At least, it takes a long time before you know all of them. Shoot me if I'm wrong, but I think a raytracer is "smaller"/simpler because all the effects you can achieve are done in the same way, based on relative simple physic laws. On the other hand, if you want to write a fast RT, you need to know your optimizations very well. Lousy programming leads to unacceptable slow rendering I guess. Although this was probably also true with rasterization when writing Quake 1. As the hardware speeds up, the tolerance for "bad programming" grows. But at this point, would you say writing a Raytracer is more difficult than a normal renderer(with all the special effects used nowadays) 7.- I'm not planning to use RT for big projects anywhere soon. I just like to play around for now. But nevertheless, what can I expect in the nearby future(5 years)? I think some of the RayTracers made are already capable of running simple games. But how does a RT coop with - Big/open scenes (Farcry) - Lots of local lights (Doom3) - Lots of dynamic objects (a race game) - Sprites / particles / fog - Post FX (blurring, DoF, Tone Mapping, Color enhancement, ...) - Memory requirements Or maybe any other big disadvantage that I need to be aware of before using RT blindly? 8.- So, where to start? Is there something like a "ray-tracing for dummies", or a Nehe tutorial kinda like website? Allrighty. Looking forward to your responses! Rick

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Quote:
 Original post by spek1.- So... which technique is the most practical(fastest) for realtime/games?I've read a little bit ray-tracing and photon mapping. Are these 2 different things?

Photon mapping is a technique used to solve the global illumination problem, expecially the indirect contribute of lighting and for things like caustics. Basic Raytracing doesn't take into account indirect illumination, so the two tecniques can be used togheter: PM to precompute indirect illumination and caustics, and RT to render the scene using the Photon map to add the indirect contribute.

Quote:
 2.- Lights. From what I read so far I shoot rays from my eyes. They collide somewhere, but at that point we don't know yet if that point is litten yes/no. How to find that out? Shoot a ray from that point to all possible lightsources? And how about indirect lighting then? I could do it reversed, starting at the lights, but then there is not telling if its rays ever reach the camera.

You are right. You shot the 'shadow ray' from your point to each light source (at least, those that you want to compute, you can discard those that are too far or too weak if you want).
Indirect illumination, as said, is not included by standard RT, so you need to use something else (radiosity, photon mapping, path tracing and so on).

Of course you can also generate rays from the lights: this is what the original raytracing was about: what we call raytracing actually is Backward Raytracing. Anyway, Bidirectional Path Tracing and Photon Mapping both shot rays from light sources, and both use methods to ensure that rays are not wasted (in both rays starting from lights are only a step of the whole rendering: there are rays starting from the eye anyway)

Quote:
 3.- Does a RT still need OpenGL/DirectX/shaders ? I guess you can combine both (for example, render a scene normally, and add special effects such as GI/Caustics/Reflections via RT). What is used in common?' I can imagine a shader is used on top to smooth/blur the somewhat noisy results of a RT producedscreen.

Raytracing is sometimes used by games engine (IIRC) to achieve some effects, but GPU are not suited for these tasks. Many real time raytracers (like Arauna) render to a texture and then use shaders to perform tone mapping and appy other filters.

Quote:
 4.- How does RT access textures? I suppose you can use diffuse textures and normal/specular/gloss Maps just as well. You just access them via the RAM and eventually write your own filtering method? If that is true, it would mean you have lots of 'texture memory' and can directly change a texture as well (draw on it for example).

As long as you write a software raytracer you can do what you want with textures (images, procedural, functions of other parameters like distance from the camera and so on). In my raytracer I can use a texture to modulate another. Lightwave let you use a texture as a render target, so you can have a texture that displays the same scene from another point of view (as in a security camera).

Quote:
 5.- Ray tracing has lots to do with collision detection. Now this is the part where I'm getting scared since my math is not very well. I wrote octrees and several collision detection functions, but I can't imagine them fast enough to run millions of rays... I mean 800x600 pixels = 480.000 rays. And that number multiplies if I want reflections/refractions(and we most certainly want that!). Do I underestemate the power of the CPU('s), do I count way too much rays, or is it indeed true that VERY OPTIMIZED algorithms are required here?

Download Arauna by Jacco Bikker from the web: it is most probably the faster raytracer you can find, so you can see it for yourself what you can get from raytracing and what not. Be warned that such speed can be achieved only with a VERY HUGE work!

Quote:
 6.- Overall, how difficult is writing a RT? Writing a basic OpenGL program is simple, but implementating billions of effects with all kind of crazy tricks(FBO's, shaders for each and every material type, alpha blending, (cascaded) shadowMaps, mirroring, cubeMaps, probes, @#%$#@$) is difficult as well. At least, it takes a long time before you know all of them. Shoot me if I'm wrong, but I think a raytracer is "smaller"/simpler because all the effects you can achieve are done in the same way, based on relative simple physic laws.

Writing a raytracer is not all that hard: you must write everything from scratch, but if you already wrote spatial structures and ray/triangle routines, then you can go with the interesting part soon. You will discover how easy is getting new effects once the core is working. Of course, designing a full-featured raytracer is another beast...

Quote:
 On the other hand, if you want to write a fast RT, you need to know your optimizations very well. Lousy programming leads to unacceptable slow rendering I guess. Although this was probably also true with rasterization when writingQuake 1. As the hardware speeds up, the tolerance for "bad programming" grows. But at this point, would you say writing a Raytracer is more difficult than a normal renderer(with all the special effects used nowadays)

The main performances related critical points with raytracing are well known: ray/primitive intersections, bad spatial structures, cache misses, texture sampling and so on. The there are higher and lower levels of optimization (ray packing to enhance cache coherence and SSE patterns, multiple importance sampling to reduce noise in monte carlo sampling and so on...)

Quote:
 7.- I'm not planning to use RT for big projects anywhere soon. I just like to play around for now. But nevertheless, what can I expect in the nearby future(5 years)? I think some of the RayTracers made are already capable of runningsimple games. But how does a RT coop with - Big/open scenes (Farcry) - Lots of local lights (Doom3) - Lots of dynamic objects (a race game) - Sprites / particles / fog - Post FX (blurring, DoF, Tone Mapping, Color enhancement, ...) - Memory requirementsOr maybe any other big disadvantage that I need to be aware of before using RT blindly?

IMHO RT should handle open scenes better than rasterization.
Raytracing handles local lights better than rasterization.
Raytracing handles dynamic object (probably) not as easily as rasterization.
Sprites and so on... no problem.
Post FX: everithing you want and even more (you can made separate channels for everithing :-)
Memory Req: kd-tree can be a problem with very complex geometry, and probably memory usage of a rasterized scene will require less memory (probably)

Quote:
 8.- So, where to start? Is there something like a "ray-tracing for dummies", or a Nehe tutorial kinda like website?

On DevMaster.net you can find a good RT tutorial series.

Good luck with your RT :-)

EDIT: when I say RT handles this better than rasterization, I don't mean that doing the same thing with RT is faster... there are other parameters (quality, special cases to take into account, efficency just to tell some).

EDIT 2: there are not many good & free resources that cover RT on the web. There are a few tutorial (the one I linked is the best one IMHO) and many papers written by researchers. But if you want to avoid wasting hours, I suggest you to write your first small RT following the tutorials, and then buy a book.
You can take a look on ompf.org where there are highly skilled people working on RT and related techniques.

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Maybe you will also find this book interesting:
http://www.pbrt.org

Regarding realtime raytracing you may also find this interesting:
http://www.mpi-inf.mpg.de/~guenther/BVHonGPU/index.html

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Quote:
 Original post by nmiMaybe you will also find this book interesting:http://www.pbrt.orgRegarding realtime raytracing you may also find this interesting:http://www.mpi-inf.mpg.de/~guenther/BVHonGPU/index.html

PBRT is a wonderful book, but I would never suggest it to someone who is going to write his first raytracer: it focuses on physically based rendering, and most of it covers advanced techniques like sampling, global illumination, sampling, BSDF, sampling and design issues (sorry for the 3 'sampling', but pbrt really gives a LOT of pages to this subject)...

I never read 'Raytracing from the ground up', but from the table of contents it seems that it might be better suited for beginners (I'm thinking about buying it, since I sometimes find very hard to understand PBRT)...

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Merci beaucoup for this kickstart! I'm exited about writing my first RT. It doesn't have to be high quality at all, I have my other (rasterization) game/hobby/project for that. I hope I can find time though. 24 hours per day is just not enough to work, please a girlfriend, hang out with friends, learn cooking, do some sports, and raise a little kid :)

Therefore I forgot one question. Are there already API's like OpenGL/DirectX for RT? Writing everything yourself is more fun, but... I guess the answer is 'yes', but maybe there are not really high quality or 'universal' libraries (yet). I've seen the name "Arauna" flashing by several times. Is this based on an existing API/tools, is it a library itself?

And then there is the hardware. From what I understand, Intel Larrabee is trying to give a boost. But what exactly is it? A specialized CPU, like the GPU? In which ways is it going to help, does it come with an API, ... And when is it available?

Probably there won't be any computers that get this piece of hardware by default. Just like the Agea physics card. I have no idea if that card works good, but as long as the average user/gamer does not have this equipment, its not really helping the developer, unless he/she is willing to write additional code that supports this hardware. So, I guess its wise just to write a RT focussing on my current hardware (Intel dual core CPU, 2000 Mhz).

Quote from devmaster Jacco
"And believe me, you haven't really lived until you see your first colors bleeding from one surface to another due to diffuse photon scattering…
"
That reminds me of seeing my first 2D sprite tank moving 8 years ago :) Pure magic

Thanks!
Rick

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Quote:
 Original post by spekMerci beaucoup for this kickstart! I'm exited about writing my first RT. It doesn't have to be high quality at all, I have my other (rasterization) game/hobby/project for that. I hope I can find time though. 24 hours per day is just not enough to work, please a girlfriend, hang out with friends, learn cooking, do some sports, and raise a little kid :)

Yeah, I know, that's why my current RT is currently waiting on my hdd :-)

Quote:
 Therefore I forgot one question. Are there already API's like OpenGL/DirectX for RT? Writing everything yourself is more fun, but... I guess the answer is 'yes', but maybe there are not really high quality or 'universal' libraries (yet). I've seen the name "Arauna" flashing by several times. Is this based on an existing API/tools, is it a library itself?

There is something around, but AFAIK nothing really interesting nor standard. There has been a lib named OpenRT somewhere, but I don't know if it is free, or still developed.
Arauna has been developed from scratch, and has been already used for two small games, so I suppose thatcan be used as an engine (the author is a member of Gamedev, chance are he will reply here as well). If what you want is a game, then you might use existing tools, but really, I think that you will feel happier by doing it yourself :-)

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 And then there is the hardware. From what I understand, Intel Larrabee is trying to give a boost. But what exactly is it? A specialized CPU, like the GPU? In which ways is it going to help, does it come with an API, ... And when is it available?

Larrabee will be a x86 based processor (up to 32 cores IIRC). It's much like as if we had to work with a standard CPU, it will just be optimized for highly parallel tasks. Since Intel used to advertise it using the 'raytracing' word thousand of times, I suppose they will provide a RT api, but I'm not sure. We wont see Larrabee until late 2009 (perhaps 2010), so you still have time to learn RT :-)

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 Probably there won't be any computers that get this piece of hardware by default. Just like the Agea physics card. I have no idea if that card works good, but as long as the average user/gamer does not have this equipment, its not really helping the developer, unless he/she is willing to write additional code that supports this hardware. So, I guess its wise just to write a RT focussing on my current hardware (Intel dual core CPU, 2000 Mhz).

Intel states that Larrabee will enter the market as a competitor to nVidia and ATI, and they will provide OpenGL and DX driver. Selling it as a specialized device would be a suicide. The only question is: will it be able to offer the same performances as nVidia and ATI will?

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 Ok, time to click your link :)Quote from devmaster Jacco"And believe me, you haven't really lived until you see your first colors bleeding from one surface to another due to diffuse photon scattering…"That reminds me of seeing my first 2D sprite tank moving 8 years ago :) Pure magic

Well, i never implemented GI yet, but also looking at your first RT shaded sphere is a wonderful experience.

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 Original post by spekAnd then there is the hardware. From what I understand, Intel Larrabee is trying to give a boost. But what exactly is it? A specialized CPU, like the GPU? In which ways is it going to help, does it come with an API, ... And when is it available?

Here is a paper about the Larrabee architecture:
http://softwarecommunity.intel.com/UserFiles/en-us/File/larrabee_manycore.pdf

Basically they just put many Pentium processors into one chip. Single-threaded applications will not benefit from this, but parallel applications like a RT will.

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Glad I am no the only one. I don't understand why the code snippets in the pbrt book recursively refer to other code snippets. Having code is already a distraction in understanding the concepts.

Do you recommend other real time ray tracers?

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 I never read 'Raytracing from the ground up', but from the table of contents it seems that it might be better suited for beginners (I'm thinking about buying it, since I sometimes find very hard to understand PBRT)...

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Original post by rumble
Glad I am no the only one. I don't understand why the code snippets in the pbrt book recursively refer to other code snippets. Having code is already a distraction in understanding the concepts.

Do you recommend other real time ray tracers?

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 I never read 'Raytracing from the ground up', but from the table of contents it seems that it might be better suited for beginners (I'm thinking about buying it, since I sometimes find very hard to understand PBRT)...

For code reference there are many OS RT:
-PovRay
-YAFRAY
-PBRT
-WinOSI
-SunFlow
-Blender

-Just to tell a few on the top of my head. None of them aim to real time though and honestly I don't know of any other OS RTRT except of Arauna (I wont be interested in RTRT until I feel comfortable with RT in the first place, because making RT real time is way beyond my possibilities :-(
I don't think there are many others OS RTRT that can compete with Arauna (and that are still actively mantained), if any.

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There's a tutorial here (not yet complete, I know, need to translate the rest..) :

Raytracer in C++

LeGreg