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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?

#### Archived

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# OpenGL OpenGL Camera system

This topic is 5391 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

## Recommended Posts

I was trying to make a camera system in OpenGL and I heard since there is no camera you just move and rotate everything else. I tried to come up with how to do this last night and I just implemented it this morning so its pretty messy. But here is what I have. float CameraRot[] = {0.0f, 0.0f, 0.0f}; float CameraPos[] = {0.0f, 0.0f, 0.0f}; //arrays for holding cameras position and rotation In my input handling I have this. //this seems to work fine and it makes it seem like the camera is moving right, left, back, and forward if (keyPressed[''W'']) CameraPos[2] = CameraPos[2] + 0.1f; if (keyPressed[''S'']) CameraPos[2] = CameraPos[2] - 0.1f; if (keyPressed[''D'']) CameraPos[0] = CameraPos[0] - 0.1f; if (keyPressed[''A'']) CameraPos[0] = CameraPos[0] + 0.1f; //this stuff is supposed to make it seem like the camera is turning left and right, it seems to work ok when camera is at origin, but afetr i have moved the camer it starts working all screwy if (keyPressed[''Q'']) CameraRot[1] = CameraRot[1] - 0.5f; if (keyPressed[''E'']) CameraRot[1] = CameraRot[1] + 0.5f; In my rendering I have this. glLoadIdentity(); if (CameraRot[0] >= 360.0f) CameraRot[0] = 0.0f; if (CameraRot[1] >= 360.0f) CameraRot[1] = 0.0f; if (CameraRot[2] >= 360.0f) CameraRot[2] = 0.0f; glTranslatef(CameraPos[0], CameraPos[1], CameraPos[2]); glRotatef(CameraRot[0], 1.0f, 0.0f, 0.0f); glRotatef(CameraRot[1], 0.0f, 1.0f, 0.0f); glRotatef(CameraRot[2], 0.0f, 0.0f, 1.0f); //then I Push a matrix and draw everything else, then Pop one at the end. My goal is to have a camera that can move left, right back and forth in relation to where it is facing, and be able to rotate up, down, left, and right. If anyone has made a camera system and would like to share with me how I am going wrong or if I have the wrong idea totally, it would be much appreciated. I am not getting syntax errors or anything like that, its just the camera does not rotate correctly at all.

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Look at gametutorials.com, they have a pretty good time based movment tutorial.

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youre doing what everybody is starting with and which you will at some point realize cant work for any nontrivial case.

you want to move forward, sideways depending on where youre camera is facing, so obviously you need to either store that information or extract it. hint: store it.

youre rotation is the good old "i''ll just store three angles and.. somehow it doesnt work". angles alone arent enough to store your orientation (at least not without a lot more work thats not worth it).

the minimum you need is two vectors (i.e. viewing direction and "up" or "right"). also the position, so we''re at 3x3 values. add some more, make it 4x4 and you get the good old transformation matrix, storing right, up, forward and position vectors.

nothing special, but hiding all the tedious trigonometry and resulting in the shortest code i could come up with (if you ignore all the culling code etc.):

its letting opengl do all the math hoping for more optimized versions than what one would hack together with math.h.. the drawback is that writing and reading the modelview matrix might hurt the performance. but since you most likely wont do this more than 1-2 times per frame i wouldnt worry (the same code can be used for objects, though obviously i''d only do this in d3d and/or do some profiling in opengl first)

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this is a very good file you posted there. You mind if I post it up on my site? You can have all the rights and whatever, just trying to put helpful files on my site for programming.

Higher Forces

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Thanks I went over the gametutorials site, and basically copied the CCamera Class code from it to make it sure it worked in my app, and I am basically going over it right now so I can understand exactly how they do it, they seem to use gluLookAt, while I got the impression it was possible with out that.

Trienco I read your post and Im pretty sure I understand what you mean, I just downloaded your code but I havent looked over it, thanks for the help, I was wondering about how to do a camera last night, and this idea popped up in my head, it seemed like it would work, I was very suprised when I got done coding it this morning and the rotations simply would not work ;(

Although I havent looked at your code yet, if I were to use gluLookAt();, then as I remember from Geometry class I would make the Look at parameter 1 unit away from my position parameter and use Cosine and Sine(theta equaling the angle which I wanted to turn) and from all the unit circle stuff I learned the the 2 numbers I got would equal the x and y of the Look At position would it not?

EDIT I got the gametutorials code up and running in my app, but I looked at Triencos code and thanks alot man, I read the readme and although in a few days Im going to right my own camera code Im going to look over yours to see how you organized it and also thanks for the frustum culling bit that should be helpful.

[edited by - rickwi22 on June 17, 2003 3:45:42 PM]

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quote:

this is a very good file you posted there. You mind if I post it up on my site? You can have all the rights and whatever, just trying to put helpful files on my site for programming.

no prob.. if you consider it worth mentioning and/or helpful just go along. and i dont think it is special enough to care about any rights ,-)

quote:

it seemed like it would work, I was very suprised when I got done coding it this morning and the rotations simply would not work ;(

part of it will work. as long as you stick to simple first person style it shouldnt cause any problems.
the problem is, that if you just update angles you loose all information about when which rotation was applied. think about it. if you rotate up, then roll left and then up again then the up rotations are in completely different directions.

glrotate will always rotate in local space which is changed by the rotations. thats why just storing the sum of all rotations won''t work.

for first person you would simply rotate around 0,1,0 first (the global up) and then around 1,0,0 (by now the local right). a simple way but only working because one axis is independent of the other.

quote:

and from all the unit circle stuff I learned the the 2 numbers I got would equal the x and y of the Look At position would it not?

quite right, as long as you stick to 2 dimensions. for up/down you have to go from there. but keep in mind that this way you rotate around global axes.
maybe missing a few cases but i''d say for first person go with two angles and for anything else use a matrix or quaternions.

quote:
Im going to look over yours to see how you organized it and also thanks for the frustum culling bit that should be helpful.

hm.. "organized" doesnt sound like code from me *lol* anyway, you''ll find versions for local and global transformations. one reason is for mentioned first person usage the other that for some things you might want to influence it from "outside" and independent of its current orientation.

culling is a little different from the common approach. for one reason, because its the way that feels more "natural" to me after coming up with it in conjunction with a radar and also because it doesnt require extracting or updating normals and should take a few dot products less.

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I dont know if you have ever looked at the gametutorials code, but it seems to use vector math and stuff like to move the camera, how do I do it "using matrixes and quaternions". Right now I use code based off the gametutorials site, where I move the mouse to look around, press "w" and "s" to go forward and backward, and "a" and "d" to strafe right and left.

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its not much difference.. if you do the vector math yourself you will have to construct a matrix (or use glulookat which is doing the same). if you''re lazy like me then you dont want to worry about keeping it orthonormal and use slow sin/cos functions and just hope that the functions of opengl are more efficient.

when you rotate you most likely recalculate two vectors, when i rotate i tell opengl to apply it to the matrix (which will transform all 3 vectors and hopefully doesnt even think about changing the position vector). depending on how often you rotate the camera in one frame its more or less work. you transform one more vector, but you dont have to do the cross products and normalizations. the code is shorter and "cleaner" but the result and the math going on is quite the same.

the "matrix"-way is what you find in my download for opengl and d3d. quaternions would just be another way to do the rotations.