Multisampling in SharpDX - sharpdx

So I have recently started using SharpDX, and have stumbled into a problem. I have no idea how to get SharpDX to multisample. I have found two things related; you can specify a SampleDescription when creating the SwapChainDescription, but any input other than (1, 0) throws a Wrong Parameter exception.
The other thing I found was SamplerState, which I put on my pixel shader, didn't do anything. I played around a lot with the parameters, but there was no visible change whatsoever.
I am sure I am missing something, but without any previous directX knowlegde I have no idea really what exactly to look for.

This will come in handy in your case:
int maxsamples = Device.MultisampleCountMaximum;
int res = device.CheckMultisampleQualityLevels(SharpDX.DXGI.Format.R8G8B8A8_UNorm, samplecount);
If res returns 0 then this Sample count is not supported.
Also please note that some options are not compatible, so if you create your SwapChain with:
sd.Usage = (other usages) | Usage.UnorderedAccess;
You are not allowed to use multisampling.
Another very useful technique to spot the problems for those errors:
Create your device with DeviceCreationFlags.Debug
In your startup project properties (debug section), tick "Enable native code debugging".
Any API call that fails will give you an error description in the debug output window.

I had the same problem, could not get Multisampling to work until I enabled the debugging and got a good hint (really wished I had done this hours ago and saved a whole lot of testing!).
Initially I read somewhere that the DepthStencilBuffer had the same SampleDescription as the Render texture - but I'm not so sure as it appears to work without this as a quick test just showed.
The thing for me was to create the DepthStencilView with a DepthStencilViewDescription that has "Dimension = DepthStencilViewDimension.Texture2DMultisampled".

Just a heads up on when you are doing multisampling.
When you set your rendertarget, if passing a rendertarget and depthstencil, you need to ensure they both have the same multisampling level.
So, for rendering to the backbuffer you have defined with MSAA, you will need to create a depth buffer with the same MSAA level.
BUT, if you are have a rendertarget that will be a texture that is fed back into the pipeline, you can define a non MSAA texture and a NON MSAA depth buffer, which is handy as you can use a sampler on the texture (you cant use a normal sampler for a MSAA Resource texture).
Most of this info maybe not new for you.

Related

Is reusing a WebGLProgram a good idea?

Instead of creating new WebGlProgram's using gl.createProgram() is it a good idea to keep reusing one?
I am listing the steps that I should be doing if I am to reuse one:
AttachShader(s): in my case I need to attach a new Fragment shader only. (Question: Can I hang on to a compiled shader?)
linkProgram
useProgram
getAttribLocation
getUniformLocation
What are you trying to do? 99.9% of all GPU apps make shader programs and are done. They might make 1, they might make 5000, but they aren't ever in a position where they would even need to consider your question. So what are you really trying to do?
Those few apps that do allow you to edit shaders (shadertoy, glslsandbox, vertexshaderart, ...) either make new ones and delete old or reuse. There's no benefit to one or the other it's just a matter of style.
Yes you can hold on to shaders. You can use shaders with multiple programs. It's common to do so.
If you change a shader it won't affect a program unless/until you relink that program with gl.linkProgram. Anytime you call gl.linkProgram and it's successful all your previous uniform locations for that program are obsolete and you have to query new ones.

What is the result of sample with an uninitialized texture in DirectX?

The OpenGL has its description about this, but how about DirectX?
In my guess, the sample result is float(0, 0, 0, 0), or arise a crash by the driver. Whatever, it just my guess, or partial case if tested it myself only. I want to make it clear.
The uninitialized texture means, did not pass any data with D3DDevice::CreateTexture2D(), and also, did not map nor update resource.
I want to take the description about DirectX 11 version if possible.
From the Create2DTexture function (that you linked):
If you don't pass anything to pInitialData, the initial content of the memory for the resource is undefined. In this case, you need to write the resource content some other way before the resource is read.
Undefined can mean anything, the driver will determine the exact behavior. It's unlikely that it will crash, but as with undefined behavior, anything is possible. A sample from this texture is certainly not guaranteed to be float4(0,0,0,0) as it is with an unbound texture.
It's analogous to accessing uninitialized system memory. The contents might be filled memory written from previous operations that had allocated the same memory (depending on the allocator's behavior). I would suggest if you want consistent behavior, either use an unbound texture instead, or, initialize the contents.
Yes you get 0 for all values its the same if you sample from a null texture.
I cant remember where it was that I read it but I know its in the MSDN doc, I also happen to do this from time to time because I allocate most of the textures\buffers\views at the start and fill as I go and if I sample from null or uninitialized then it just read 0.

Loading a texture from file post DX11.1?

In 11.1 and later Microsoft removed a lot of helpers for loading textures (fromfile, fromstream etc).
I'm trying to port my code over to 11.2 and everything works fine except for this line :
var texture = Texture2D.FromFile<Texture2D>(device, #"C:\Texture.png");
Now all i could find was guidance telling me to use WIC instead but i can't seem to find anything providing me with a Texture2D that is nearly as versatile (all the samples i found require passing in the pixel format among other things).
I'm looking for a solution that would let me load files (without knowing their format or layout before hand) and get a Texture2D out of it just like FromFile allowed. Is there anything like that or even close? I'm assuming there has to be "something" as they wouldn't just deprecate such a feature if it wasn't superfluous.
Any help is most appreciated.
Edit : I'd like to avoid using the SharpDX.Toolkit too, i'm looking for a raw DirectX / WIC etc solution as i don't want to add a dependency on the Toolkit. I'm however perfectly fine on adding any .net Framework 4.0 or 4.5 assembly as a dependency.
There is no easy solution apart from writing the whole WIC interop yourself. Even if you don't want to use the Toolkit, the source code is available and the class WicHelper.cs responsible for decoding images is fairly easy to adapt.
If you want a very simple solution that doesn't handle all WIC cases (format mappings...etc.), you can have a look at TextureLoader.cs.
Provided you have both a Texture2D and a WPF BitmapImage lying around, something like this will help:
var map = device.ImmediateContext.MapSubresource(texture, 0, MapMode.WriteDiscard, MapFlags.None);
bitmap.CopyPixels(Int32Rect.Empty, map.DataPointer, bitmap.PixelWidth * bitmap.PixelHeight * 4, bitmap.PixelWidth * 4);
device.ImmediateContext.UnmapSubresource(source, 0);
The function you mention was probably something fairly similar under the hood.
If you're not sure about the bitmap being Bgra, you have to convert it first.

How to make a change in Qualcomm's Vuforia Sample App

I have been looking through the threads at the Qualcomm Forums but no luck since I don't know exactly how to look for what I want.
I'm working with the ImageTargets Sample for iOS and I want to change the teapot to another image (a text rather) I had.
I already have the render and I got the .h using opengl library but I can't figure out what do I need to change to make this work and since this is the very basic and I haven't been able to make it work I really haven't ventured to try anything else.
Could anyone please help me out?
I would paste code here but it's a whole project so I don't know exactly what to put if needed please let me know.
If the case is still valid, here's what you have to do:
get header file for 3D object
get texture image for this object
in EAGLView.mm make this changes:
import "yourobject3d.h"
add your texture to textureFilenames array(this should be at the begining of EAGLView
eventually take care about kObjectScale (by deafult it was about 3.0f, for one object I did have to change it even up to 120.0f)
in setup3dObjects method assign proper arrays of vertices/normals/texture coords (check in "yourobject3d.h" file for proper arrays and naming) to Object3D *object
make this change in renderFrameQCAR
//glDrawElements(GL_TRIANGLES, obj3D.numIndices, GL_UNSIGNED_SHORT, (const GLvoid*)obj3D.indices);
glDrawArrays(GL_TRIANGLES, 0, obj3D.numVertices);
I believe that is all... if something take a look at Vuforia's forum, i.e. here: https://developer.vuforia.com/node/2047669
NOTE: default teapot.h does (!) have indices, which are not present in banana.h (from comment below) so take care about that too
Have a look at the EAGLView.mm file. There you'll have to load the textures (images) and 3d objects (you'll need to import your .h instead of teapot.h and modify setup3dObjects accordingly).
They are finally rendered by calling the renderFrameQCAR function.
Actually, teapot is not an image. It's a 3D model stored in .h format which includes Vertices, Normals, and Texture coordinates. You should have a good knowledge of OpenGL ES to understand those codes in sample app.
An easier way to change the 3D model to whatever you want is to use a rendering engine which facilitates the drawing and rendering stuffs and you don't need to bother OpenGL APIs. I've done it with jPCT-AE for Android platform but for iOS there is a counterpart called OpenFrameworks engine. It has some plugins to load 3Ds or MD2 files and since it's written in C++ you can easily integrate it with QCAR.
This is a short video of my result with jPCT and QCAR:
Qualcomm Vuforia + jPCT-AE test video

Using 3D Studio Max DirectX shader in XNA problem

UPDATE 2: It now appears this is more of a modelling issue than a programming one. Whoops.
I'm new to XNA development, and despite my C# experience, I've been stuck at one spot for going on two days now.
The situation: I've created a model in 3D Studio Max 2010 which uses two materials, both are of type DirectX Shader. The model exports to FBX without error and Visual Studio compiles it properly. When I ran the Draw() method initially, it threw an exception on the 'BasicEffect' portion of one of my loops, demonstrating (at least to me) that it was loading the .fx file correctly, which must be embedded in the FBX file or something.
The problem:
When using the following code
foreach (ModelMesh mesh in map.Meshes)
{
foreach (Effect effect in mesh.Effects)
{
effect.CurrentTechnique = effect.Techniques["DefaultTechnique"];
effect.Begin();
effect.Parameters["World"].SetValue(Matrix.CreateTranslation(Vector3.Zero));
effect.Parameters["View"].SetValue(ActiveCamera.ViewMatrix);
effect.Parameters["Projection"].SetValue(ActiveCamera.ProjectionMatrix);
effect.Parameters["WorldViewProj"].SetValue(Matrix.Identity * ActiveCamera.ProjectionMatrix);
effect.Parameters["WorldView"].SetValue(Matrix.Identity * ActiveCamera.ViewMatrix);
foreach (EffectPass ep in effect.CurrentTechnique.Passes)
{
ep.Begin();
// something goes here?
ep.End();
}
effect.End();
}
mesh.Draw();
}
The only thing that happens is a white box appears covering the bottom half of the screen, regardless of camera position or angle. I got the name of the effect parameters of the default.fx file specified in Max (it's at [program files]\autodesk\3ds Max 2010\maps\fx).
I get the feeling I'm setting one or all of these incorrectly. I've tried to look up tutorials and follow their code, however none of it seems to work for my model.
Any help or ideas?
UPDATE:
By making these changes:
effect.Parameters["WorldViewProj"].SetValue(Matrix.CreateTranslation(Vector3.Zero) * ActiveCamera.ViewMatrix * Conductor.ActiveCamera.ProjectionMatrix);
effect.Parameters["WorldView"].SetValue(Matrix.CreateTranslation(Vector3.Zero) * ActiveCamera.ViewMatrix);
The model was able to draw. However, everything is completely white :(
Unfortunately, especially without seeing your shader and/or knowing what error it is that you're getting, it's going to be pretty difficult to figure out what's wrong here. There are a number of things that could be going wrong.
My suggestion is to start with a simpler test. Make a box, apply a very simple shader ... and make that render. Then, add some parameter that (for example) multiplies the red component of the pixel shader by the amount passed in. And make that render successfully.
By simplifying the problem set, you are figuring out the nuances of the shaders that max exports and how you set the properties. At some point, you'll realize what you're doing wrong and will be able to apply that to your more complex shader.
I'm quite interested in hearing how this goes ... make sure you comment on this once you've fixed it so I see the outcome. Good luck! :-)

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