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• 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?

• I am somewhat new to game development and trying to create a basic 3d engine. I have managed to set up a first person camera and it seems to be working fine for the most part. While I am able to look up, down, left and right just fine the camera is constrained to the mouse movement in the window (i.e when the mouse reaches edges of the window it discontinues camera rotation and mouse is out of window bounds. I tried to use SDL_WarpMouseInWindow(window, center.x,center.y) but when I do this then it messes up the camera and the camera is stuck, even though there is some slight movement of the camera, it keeps going back to the center.
void Camera::UpdateViewByMouse(SDL_Window &window, glm::vec2 mousePosition)
{
float xDistanceFromWindowCenter = mousePosition.x - ((float)1024 / 2) ;
float yDistanceFromWindowCenter = ((float)720 / 2) - mousePosition.y;
yaw = xDistanceFromWindowCenter * cameraRotationSpeed;
pitch = yDistanceFromWindowCenter * cameraRotationSpeed;
SDL_WarpMouseInWindow(&window, 1024 / 2, 768 / 2); }
i’ve been stuck on this for far too long. any help would be much appreciated
i have also tried relative mouse movement,  and .xrel and .yrel to avail. polling mouse state with sdl_event. I do also know that SDL_WarpMouseInWindow makes change to event and have tried also ignore and reenabling to no avail

# OpenGL Quaternions and a rotating ball

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Hey, I'm having some problems to get a ball rotating. I have a ball moving along the XZ-plane which I want to get rotating nicely. This leads me to what seems to be one of the most usual problems regarding rotating (glrotatef since I use opengl): it's kinda hard to rotate something around two world-axis (non object-local). I've read about the quaternions on a few sites and finally decided to do as in the NeHe-tutorial (http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=Quaternion_Camera_Class) which seems ideal for this. What I do is that I calculate how far the ball has moved in the Z and X-direction and translates that to how many degrees the ball have rotated. I keep track of these angles of rotation about the absolute X and Z-axis. Since two rotations won't do it I create to quaternions, one for each axis:
GLfloat Matrix[16];
glQuaternion result, xaxis, zaxis;
xaxis.CreateFromAxisAngle(1.0, 0.0, 0.0, player->getRotationX());
zaxis.CreateFromAxisAngle(0.0, 0.0, 1.0, player->getRotationZ());
result = xaxis*zaxis;
result.CreateMatrix(Matrix);
glMultMatrixf(Matrix);
But I still get odd rotations. For example, when the rotation around the X-axis is 90 degrees and I move along the X-axis the ball rotates around the Y-axis, which is exactly what happens when you use glrotatef twice (since the Z-axis points downwards after the rotation around the X-axis). I've been trying to get these silly quaternions to work the last 4 hrs and I'm starting to get kinda irritated on them :) Does anyone have any ideas?

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Quote:
 Original post by noofGLfloat Matrix[16];glQuaternion result, xaxis, zaxis;xaxis.CreateFromAxisAngle(1.0, 0.0, 0.0, player->getRotationX());zaxis.CreateFromAxisAngle(0.0, 0.0, 1.0, player->getRotationZ());result = xaxis*zaxis;result.CreateMatrix(Matrix);glMultMatrixf(Matrix);But I still get odd rotations. For example, when the rotation around the X-axis is 90 degrees and I move along the X-axis the ball rotates around the Y-axis, which is exactly what happens when you use glrotatef twice (since the Z-axis points downwards after the rotation around the X-axis). I've been trying to get these silly quaternions to work the last 4 hrs and I'm starting to get kinda irritated on them :)
Using quaternions is gaining you absolutely nothing here. In short, if one can't make something work with matrices, they probably won't be able to get it to work with quaternions; the latter has some advantages over the former, but the fundamental properties of the two representations are the same.

So I'd drop the quaternions for now. As for getting the ball to roll in a somewhat realistic way, here's what occurs to me (short of an actual physics-based simulation). The axis of the ball's rotation is perpendicular to a) the ball's direction of motion, and b) the normal of the surface on which it is moving. In this case it is always uniquely defined, so you can just take the normalized cross product of the velocity and up vectors. Then, you can find the amount of rotation from the ball's circumference and the distance it's traveled. You can acumulate this angle over time and then feed the axis-angle pair to glRotate().

There might be other issues involved if your ball changes direction. This is a place where your quat class may come in handy (not because it has any special properties with respect to matrices, but rather just because you already have it available).

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Making a quaternion from euler angles, like you're doing there, is sort of like making a fancy decorated bavarian custard from spoiled milk. It's still going to taste bad. Use quaternions (or matrices) to keep track of the orientation of the ball. Don't use the "xaxis, zaxis" thing. Don't use euler angles anywhere.

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Quote:
 Original post by noofGLfloat Matrix[16];glQuaternion result, xaxis, zaxis;xaxis.CreateFromAxisAngle(1.0, 0.0, 0.0, player->getRotationX());zaxis.CreateFromAxisAngle(0.0, 0.0, 1.0, player->getRotationZ());result = xaxis*zaxis;result.CreateMatrix(Matrix);glMultMatrixf(Matrix);

Just to chime in, my first reaction to this code was "wow, this is incredibly... pointless". You probably fell for the silly "quaternions are the magical solution to all your rotation problems" and decided to just throw some in without being explained or looking up what they are, how they work and why they work.

So you create two quaternions, which are doing exactly the same thing as matrices would have and end up with a completely wasteful way to do:
glRotate(a,1,0,0);
glRotate(b,0,0,1);
just that now there is a lot of useless back and forth between all possible representations.

As pointed out above, your problem isn't using quaterions or converting Euler angles to quaternions, but the fact that you are using Euler angles at all. They are extremely useless for just about everything that isn't a typical shooter style first person camera. NEVER try and store an orientation as Euler angles, there is just no useful way to add additional rotations, unless you start converting them (ALL angles) to a (SINGLE) matrix/quaternion, apply the new rotation to that and convert back. And at this point you should realize that storing a matrix or quaternion instead of constantly converting from/to a useless representation is saving you a lot of work and trouble.

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We all have to start somewhere :)

Quote:
 Original post by jykThen, you can find the amount of rotation from the ball's circumference and the distance it's traveled. You can acumulate this angle over time and then feed the axis-angle pair to glRotate().

I actually tried that one before I found out about quaternion which makes it kinda hard to accumulate the rotation (unless you use matrices, which I didn't think of)

Quote:
 Original post by TriencoYou probably fell for the silly "quaternions are the magical solution to all your rotation problems" and decided to just throw some in without being explained or looking up what they are, how they work and why they work.

100% correct, although I started realizing that quaternions aren't as magic as I thought when I thought about them and couldn't grasp why they would solve my problem (just thought that was part of the other silly "quaternions are so hard to understand that you don't wanna waste your time doing it")

So, after reading your thoughts (thanks a lot for them btw!) I'm thinking of the following solution:
1) cross velocity vector with up-vector (plane normal) to get the vector the ball is spinning around
2) get number of degrees the ball has rotatet around that vector
3) convert that spin to a quaternion like:
glQuaternion rot;rot.CreateFromAxisAngle(degrees, spinvector.x, spinvector.y, spinvector.z);

4) "add" that rotation to the rotation accumulator:
total = total*rot;

5) rotate the ball:
GLfloat Matrix[16];total .CreateMatrix(Matrix);glMultMatrixf(Matrix);

Does this sound any better? :)

[Edited by - noof on January 20, 2006 4:54:11 AM]

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Quote:
 Original post by noof(just thought that was part of the other silly "quaternions are so hard to understand that you don't wanna waste your time doing it")

That depends on how deeply you want to understand them. But usually we only care about unit quaternions, so reducing it to axis and angle can already get you somewhere. Completely without worrying too much about all the implications of having complex numbers with not just i, but also j,k and all their properties.

Quote:
 I'm thinking of the following solution:

If I get you right you plan to store the total rotation/orientation as a quaternion and just add (well, multiply) the rotation for each update. That would be pretty much the way to do it.

Keep in mind that quaternions are smaller, not as problematic as deorthonormalizing matrices and quat-quat multiplication is a bit cheaper. But transforming something by a quaternion is a good bit more expensive. So they are usually only of interest if you really need to save memory or expect to concatenate lots of transformations so the cheaper multiplication is worth the more expensive transformation.

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Quote:
 Original post by TriencoIf I get you right you plan to store the total rotation/orientation as a quaternion and just add (well, multiply) the rotation for each update.
Yeah, that's the solution I'm thinking about trying later today.

Quote:
 Original post by TriencoKeep in mind that quaternions are smaller, not as problematic as deorthonormalizing matrices and quat-quat multiplication is a bit cheaper. But transforming something by a quaternion is a good bit more expensive. So they are usually only of interest if you really need to save memory or expect to concatenate lots of transformations so the cheaper multiplication is worth the more expensive transformation.

Ok, I don't think it'll make a huge difference in my project, but it always good to know :)

Quote:
 Original post by TriencoBut usually we only care about unit quaternions

That makes me think of another question. Do I have to normalize the quaternion after doing the "multiplication" ? like:
total = total*rot;total = total / sqrt(w^2+x^2+y^2+z^2)

because I think only x^2+y^2+z^2=1 and not w^2+x^2+y^2+z^2=1, since I will get a unit vector as the "vector part" of the quaternion, but the angle will be arbitrary, or?

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Quote:
 Original post by noofThat makes me think of another question. Do I have to normalize the quaternion after doing the "multiplication" ?

Mathematically? No, the result should also be a unit quaternion.
Technically? Every once in a while, because discrete representations of real numbers (ie. float/double) will introduce small errors that can add up. As sqrt can be kind of expensive it might be worth to check if a conditional might be better (or just normalize after every 100 or whatever multiplications). And yes, you normalize the whole thing, not just part of it (which means you can drop one -preferably positive- component if you really need every byte you can get).

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Tried the new idea and I still have the same problem. In every frame I do (rotation is the rotation accumulator as a quaternion, velocity is the normalized ball velocity vector):
Vector3D spinAxis = velocity.crossProduct(Vector3D(0,1,0)); // velocity is normalizedfloat rotationAngle = <calculates angle here>;if(!rotation) {  // first frame  rotation = new Quaternion(rotationAngle, spinAxis.getX(), spinAxis.getY(), spinAxis.getZ());} else {  // other frames  *rotation = (*rotation)*Quaternion(rotationAngle, spinAxis.getX(), spinAxis.getY(), spinAxis.getZ());}rotation->normalize(); // just to be sureglMultMatrixf(...);
Which gives me exactly the same results :( But when I think of it I would be kinda surprised if it had worked. Let's say for example that I have a really sucky frame rate and start by rolling 90 degrees of the ball along the Z-axis before frame 1. Then I turn around 90 degrees and roll the same distance along the X-axis before frame 2. In the first frame I will have:
rotation = Quaternion(90, 1, 0, 0);
and in the next frame:
rotation = rotation*Quaternion(90, 0, 0, 1);
which seems to be exactly what I had in my first attempt to use quaternions. I'm obviously missing something here, any more ideas? :)

*edit* It's working now, YEY! :D And it looks damn sweet :) I replaced:
  *rotation = (*rotation)*Quaternion(rotationAngle, spinAxis.getX(), spinAxis.getY(), spinAxis.getZ());
with:
  *rotation = Quaternion(rotationAngle, spinAxis.getX(), spinAxis.getY(), spinAxis.getZ())*(*rotation);
If someone has an explanation for why it should be that way and not the other, feel free to post a reply. (And thanks for all the help, really appreciated!)

[Edited by - noof on January 20, 2006 10:51:21 AM]