I am preparing to start on a C++ DirectX 10 application that will consist of multiple "panels" to display different types of information. I have had some success experimenting with multiple viewports on one RenderTargetView. However, I cannot find a definitive answer regarding how to clear a single viewport at a time. These panels (viewports) in my application will overlap in some areas, so I would like to be able to draw them from "bottom to top", clearing each viewport as I go so the drawing from lower panels doesn't show through on the higher ones. In DirectX 9, it seems that there was a Clear() method of the device object that would clear only the currently set viewport. DirectX 10 uses ClearRenderTargetView(), which clears the entire drawing area, and I cannot find any other option that is equivalent to the way DirectX 9 did it.
Is there a way in DirectX 10 to clear only a viewport/rectangle within the drawing area? One person speculated that the only way may be to draw a quad in that space. It seems that another possibility would be to have a seprate RenderTargetView for each panel, but I would like to avoid that as it requires other redundant resources, such as a separate depth/stencil buffers (unless that is a misunderstanding on my part).
Any help will be greatly appreciated! Thanks!
I would recommend using one render target per "viewport", and compositing them together using quads for the final view. I know of no way to scissor a clear in DX 10.
Also, according to the article here, "An array of render-target views may be passed into ID3D10Device::OMSetRenderTargets, however all of those render-target views will correspond to a single depth stencil view."
Hope this helps.
Could you not just create a shader together with the appropriate blendstate settings and a square mesh (or other shape of mesh) and use it to clear the area where you want to clear? I haven't tried this but I think it can be done.
Related
I'm surprisingly struggling a lot to display text with OpenGL ES 2.0. There are a ton of posts on stackoverflow, debating the subject, showing a few lines of code, or showing links from 2010 but working with OpenGL ES 1.x (not compatible).
But they are quite vague, and to my knowledge there is not complete code or convenient way to display text with version 2.
Do you know if there is a modern way to display text ? Like just adding a pod and writing something like this ?
[font drawText:#"This is a text" size:#12];
Thanks a lot in advance, any help would be very much liked.
EDIT 1 : I have to use OpenGL 2.0, and I can't use something else, for internal reasons.
EDIT 2 : I've found two libraries that do it :
FTGLES : It crashes at runtime when I try to use it
https://github.com/chandl34/public/tree/master/personal/c%2B%2B/Font
This one is simple but written for ES1, so I need to port the code to ES2.
EDIT 3 : ES1 and ES2 are different : ES2 works with shaders.
Since you are targeting ES2 and shaders are supported it might be a bit hard to create a tool that does this for you. But if you find such a tool it might be conflicted with your flow in many ways such as binding its own shaders and buffers, using settings on blending, depth buffer... Then if it would do that you are having trouble as you may not have a good control over how and where the text is drawn (on a 3D rotating box for instance).
But from your question (it's snippet) it seems more like all you want to do is add some 2D overlay with text which would look exactly like using an UILabel. If this is the case then I suggest you to actually use UILabel to draw these texts. You can add all of these views easily on your view that shows openGL content.
In the other case where you still need to draw text on a 3D object and want to do it very easily I suggest you to still use UILabel but create its screenshot and push it to a new (or atlas) texture. Then you can draw it as any other object. UILabel will then handle all fonts, alignments, colors, multiline and text wrapping, font size adjustments... So if you already have a system to draw a texture in the scene you should not be too far from creating yourself a tool that draws some text on the screen since you use a texture to transfer the data.
Nothing has changed since OpenGL ES1. Usually text is displayed in planar projection and created quads that are textured using font texture. There are many tutorials on this topic.
One example how to do it.
However, this is quite a lot of work when you started from scratch.
There might be better way, but depending on what you plan to do might not be suitable. You may mix UIKit with OpenGL view, having text drawn with UIKit as overlay. (UILabel, UIButton..etc.)
I'm experiencing painting issues when combining TScaledLayout and custom styles created from the bitmap style designer in fmx.
To demonstrate, I loaded the default custom style created by chosing "New style for VCL / FMX" -> "save as .style" in the bitmap style designer. I dropped several standard controls on some colored rectangles: The red & green ones on a TScaledLayout, the blue one directly on the form. As I stretch the form, colored lines appear on the controls on the ScaledLayout; the background is partially visible:
If I size the form to exactly match the design-time dimensions, the lines disappear. That seems like a pretty significant issue, I certainly can't use those two together like that. Does anybody have an idea for a possible fix or workaround?
Looks like this is a known issue with scaling and bitmaps. See the Google+ discussion here - https://plus.google.com/+PaulThornton/posts/ACAHkJD3a84. I'll quote Marco Cantu's thoughts:
I've found an internally reported issue of a similar case, but haven't
found one that matches this scenario. Certainly worth adding to quality
portal. Having said this, I fear that bitmap-based operations and
scaling don't really fit together very well, and it might be difficult
to have an all encompassing solution.
Let me explain with an example. Take a button. This is painted by FMX
with 9 sections (borders, corners, central part) so that regardless of
the size the bitmap elements are stretched in one direction at most,
often just draw. Stretching a single bitmap for the button to the
target size would break anti-aliasing and create a blurred image when
using colors.
This is example what happens with a ScaledLayout, given it takes the
complete final image and transforms it. ScaledLayout was originally
introduced with vector styles, and worked very well in that scenario.
With todays's bitmap styles things get a bit more complex.
Regardless of this explanation of there the issue lies, I'd recommend
reporting it on QC, and I'll make sure it doesn't get closed as design
(it could naturally happen, this is how the system works) but that we
do some investigation to address the issue -- turning this into a
feature request.
Is iOS using some form of dirty region rendering by default while rendering applications?
For example, if I have a graph paper background graphic on a text input field, and the user scrolls through it, will the whole graphic be redrawn every time, or only the part that has changed (In the graph paper example: If a pixel was white before and will be white on the next rendering, will it be redrawn or left alone)?
Again, this question is mostly out of curiosity and not out of programming needs. I did not find anything in the developer manuals about this.
Not only is Richard J. Ross III's comment evidence — Apple have reserved the right to do partial redraws even though the iPhone had full on-GPU composition from day one, so it isn't a legacy thing — but the advice always handed out in OpenGL sessions is to try to avoid composition of OpenGL on OpenGL or any two rapidly changing views since it causes the compositor to do a lot of extra work that you can usually avoid (by moving all the content into one OpenGL view in that specific case).
I would therefore assume the compositor has some notion of updating only dirty parts of the layer hierarchy.
I've never done OpenGL, but I'm looking for some pointers on this particular question on an AR app I'm practicing with.
I'd like to make an app with a "flat rectangle" along with text written on the surface of the rectangle. Visually, I'm imagining something along the lines of a piece of paper with text written on it. Each time the app starts, the text would be something different (the text is pulled from a plist file).
The user would be able to view the paper from all sides, much as if there was a piece of paper hanging in front of him.
Is this trivial to do in OpenGL? How could I get started?
Sorry for the really open-ended question, but I wanted to get a feel for how this kind of thing is done.
Looking at the OpenGL template source code in the Xcode sample projects, I see that there is a big array of vertices. I presume that to create a "flat" rectangle, I'd essentally just have to remove or make the z-axis zero. And then the dynamic text that will attach to the surface of the flat rectangle...I dont have any idea how to do that......
This question is hard to answer unambiguously. In general, this is trivial, but then again it is not.
Drawing a "flat rectangle with something on it" is a couple of API calls, as simple as it can get. Drawing text in OpenGL in an efficient way, and high quality, and without big preprocessing is an entirely different story.
What I would do is render text using whatever the "normal system-supported" way is under iOS (just like you would draw in any window, I wouldn't know this specific detail), but draw into a bitmap rather than on the screen. This should be supported, pretty much every OS has supported this for at least 10-15 years. Then turn this bitmap into a texture, bind it, and draw your trivial flat quad with OpenGL (set up a vertex buffer with 4 vertices, each vertex a texture coordinate, and draw two triangles - as easy as it gets).
The huge advantage of that is that you get to use the installed system fonts (or any fonts available), you don't need to generate a bitmap font and don't need to think about really ugly things such as hinting and proper spacing, and it's much easier to mix different text styles, etc. OpenGL has built-in support for text too, of course, but it is not terribly efficient or nice either. If the text does not change every millisecond, it's really best to render it using the standard renderer that the operating system provides (yes, that probably won't be hardware accelerated, but so what... since the user must read the text, it likely won't change every millisecond).
Now it gets more complicated if your "piece of paper" should bend and twist too, or do a page peel effect rather than being just a flat rectangle. In that case you need to tesselate it, which can be harder than it sounds, too. Not all tesselations look optimal for all bends/twists, or they do but do not have the optimal (read as minimum) number of vertices.
There is an article on "page peel" and such tesselation in one of the GPU Gems or GPU Pro books, let me search...
There: Andreas Bizzotto: "A Shader-Based eBook Reader - Page peeling effect", GPU Pro2 pp. 278-299
Maybe you can get hold of a copy or are lucky enough to find it on Google Books or something.
I'm writing a 3d modeling application in D3D9 that I'd like to make as broadly compatible as possible. This means using few hardware-dependent features, i.e. multisampling. However, while the realtime render doesn't need to be flawless, I do need to provide nice-looking screen captures, which without multisampling, look quite aliased and poor.
To produce my screen captures, I create a temporary surface in memory, render the scene to it once, then save it to a file. My first thought of how I could achieve an antialiased capture was to create my off-screen stencilsurface as multisampled, but of course DX wouldn't allow that since the device itself had been initialized with D3DMULTISAMPLE_NONE.
To start off, here's a sample of exactly how I create the screencapture. I know that it'd be simpler to just save the backbuffer of an already-rendered frame, however I need the ability to save images of dimension different than the actual render window - which is why I do it this way. Error checking, code for restoring state, and releasing resource are ommitted here for brevity. m_d3ddev is my LPDIRECT3DDEVICE9.
//Get the current pp
LPDIRECT3DSWAPCHAIN9 sc;
D3DPRESENT_PARAMETERS pp;
m_d3ddev->GetSwapChain(0, &sc);
sc->GetPresentParameters(&pp);
//Create a new surface to which we'll render
LPDIRECT3DSURFACE9 ScreenShotSurface= NULL;
LPDIRECT3DSURFACE9 newDepthStencil = NULL;
LPDIRECT3DTEXTURE9 pRenderTexture = NULL;
m_d3ddev->CreateDepthStencilSurface(_Width, _Height, pp.AutoDepthStencilFormat, pp.MultiSampleType, pp.MultiSampleQuality, FALSE, &newDepthStencil, NULL );
m_d3ddev->SetDepthStencilSurface( newDepthStencil );
m_d3ddev->CreateTexture(_Width, _Height, 1, D3DUSAGE_RENDERTARGET, pp.BackBufferFormat, D3DPOOL_DEFAULT, &pRenderTexture, NULL);
pRenderTexture->GetSurfaceLevel(0,&ScreenShotSurface);
//Render the scene to the new surface
m_d3ddev->SetRenderTarget(0, ScreenShotSurface);
RenderFrame();
//Save the surface to a file
D3DXSaveSurfaceToFile(_OutFile, D3DXIFF_JPG, ScreenShotSurface, NULL, NULL);
You can see the call to CreateDepthStencilSurface(), which is where I was hoping I could replace pp.MultiSampleType with i.e. D3DMULTISAMPLE_4_SAMPLES, but that didn't work.
My next thought was to create an entirely different LPDIRECT3DDEVICE9 as a D3DDEVTYPE_REF, which always supports D3DMULTISAMPLE_4_SAMPLES (regardless of the video card). However, all of my resources (meshes, textures) have been loaded into m_d3ddev, my HAL device, thus I couldn't use them for rendering the scene under the REF device. Note that resources can be shared between devices under Direct3d9ex (Vista), but I'm working on XP. Since there are quite a lot of resources, reloading everything to render this one frame, then unloading them, is too time-inefficient for my application.
I looked at other options for antialiasing the image post-capture (i.e. 3x3 blur filter), but they all generated pretty crappy results, so I'd really like to try and get an antialiased scene right out of D3D if possible....
Any wisdom or pointers would be GREATLY appreciated...
Thanks!
Supersampling by either rendering to a larger buffer and scaling down or combining jittered buffers is probably your best bet. Combining multiple jittered buffers should give you the best quality for a given number of samples (better than the regular grid from simply rendering an equivalent number of samples at a multiple of the resolution and scaling down) but has the extra overhead of multiple rendering passes. It has the advantage of not being limited by the maximum supported size of your render target though and allows you to choose pretty much an arbitrary level of AA (though you'll have to watch out for precision issues if combining many jittered buffers).
The article "Antialiasing with Accumulation Buffer" at opengl.org describes how to modify your projection matrix for jittered sampling (OpenGL but the math is basically the same). The paper "Interleaved Sampling" by Alexander Keller and Wolfgang Heidrich talks about an extension of the technique that gives you a better sampling pattern at the expense of even more rendering passes. Sorry about not providing links - as a new user I can only post one link per answer. Google should find them for you.
If you want to go the route of rendering to a larger buffer and down sampling but don't want to be limited by the maximum allowed render target size then you can generate a tiled image using off center projection matrices as described here.
You could always render to a texture that is twice the width and height (ie 4x the size) and then supersample it down.
Admittedly you'd still get problems if the card can't create a texture 4x the size of the back buffer ...
Edit: There is another way that comes to mind.
If you repeat the frame n-times with tiny jitters to the view matrix you will be able to generate as many images as you like which you can then add together afterwards to form a very highly anti-aliased image. The bonus is, it will work on any machine that can render the image. It is, obviously, slower though. Still 256xAA really does look good when you do this!
This article http://msdn.microsoft.com/en-us/library/bb172266(VS.85).aspx seems to imply that you can use the render state flag D3DRS_MULTISAMPLEANTIALIAS to control this. Can you create your device with antialiasing enabled but turn it off for screen rendering and on for your offscreen rendering using this render state flag?
I've not tried this myself though.