We've encountered a strange problem on newer laptops using built-in graphic cards.
In order to draw true-type fonts we obtain the glyph outlines using wglUseFontOutlines and then draw them with in glRenderMode(GL_FEEDBACK).
Afterwards we parse the feedback buffer. This has worked for many years.
Now we have a problem with glyphs containing holes (only on platforms with built-in graphic cards):
wglUseFontOutlines works perfectly. If we just draw the returned display lists, everything is fine. However, the token stream generated with GL_FEEDBACK is corrupt. The debugger shows nothing unusual, all functions return with success and the parsing itself works fine too. It is really the binary data generated by GL_FEEDBACK mode, which is wrong.
Has anyone else encountered this problem?
And is there an alternative way to obtain outlines and fillings for true type fonts on Windows?
I'm just guessing into the blue here: The GL_SELECT and GL_FEEDBACK rendering modes were usually not supported by widespread GPU driver OpenGL implementations. Only a handful graphics cards from the previous century actually did support these rendering modes. Hence you would almost always fall back into a software implementation when using those modes.
However given modern GPU's vastly more flexible feedback mechanisms, the latest drivers could actually try to implement those rendering modes using GPU features (somewhat weird, because those modi have been removed from modern OpenGL profiles). Anyway, this could be the reason why you're experiencing these problems.
In order to draw true-type fonts we obtain the glyph outlines using wglUseFontOutlines and then draw them with in glRenderMode(GL_FEEDBACK). Afterwards we parse the feedback buffer.
That's a cool Rube-Goldberg machine. Why don't you simply cut the middleman and obtain the glyph outlines directly using the appropriate Windows GDI functions (GetGlyphOutline) for this? This is what wglUseFontOutlines is using internally anyway.
Related
I have a shader i wrote, using the normal map generated by 3ds max. I get seamless results on windows, but i've seen seams on macs. Is this something that could be related to the directon i develop my normal map, (but then again i believe that i am running chrome in opengl mode), or some kind of precision issue? Is there any way of debugging this without a mac?
Per gmans answer below, i've added
gl.pixelStorei(gl.UNPACK_COLORSPACE_CONVERSION_WEBGL, gl.NONE);
The link is here.
Is it possible it's a color space conversion issue?
By default some browsers apply colorspace conversions when they load images. That's fine if you're just displaying an <img> tag but no so good for normal maps.
To tell WebGL to not allow to the browser to apply colorspace conversions you call
gl.pixelStorei(gl.UNPACK_COLORSPACE_CONVERSION_WEBGL, gl.NONE);
The default is that colorspace conversions are allowed (as in browser specific).
See the WebGL spec
I need to blend a few image together into a single one, pretty much as what's described here: OpenGL - mask with multiple textures.
I used the solution that is proposed there, but there's an issues with the glBlendFuncSeparate method.
Turns out that this method was introduced in later openGL versions, and according to my gl.h file the version I'm using is 1.
After much searching and reading I realized that this is what I have to work with and that I can't just upgrade my openGL version.
I went ahead and downloaded GLEW.
I added glew.h and glew.c into my VS10 project, defined GLEW_BUILD and now it finally compiles without complaining about glBlendFuncSeparate, but when I run the program it crashes when it tries to call the method, saying Access Violation, I guess that it points to NULL and then crashes when that's being run.
I continued reading and searching on this, and from what I understand, I need to use OpenGl Extensions to make it work.
If what's written in Using OpenGL extensions On Windows is correct then I'm missing something.
Let's say I do everything it says, I "download and install the latest drivers and SDKs for your graphics card" and then compile it, even if it runs on my machine, I see no guarantee that it won't crash on someone else's machine, since they might not have done the same.
I have two questions:
Am I missing something here? this whole process seems way too complicated, and environment dependent.
Is there an alternative for using glBlendFuncSeparate in this kind of a scenario?
You don't need glBlendFuncSeparate(GL_ZERO, GL_ONE, GL_SRC_COLOR, GL_ZERO); to use trick described in OpenGL - mask with multiple textures. Yes, you can't added color directly to alpha channel, like described in previous example, but you can be little tricky.
During writing your mask just disable writting all color channels, except alpha:
glColorMask(false, false, false, true);
and enable multiplying mask's alpha on background alpha-channel:
glBelndFunc(GL_ZERO, GL_SRC_ALPHA);
After writing bitmask, don't forget setup your glColorMask back.
glColorMask(true, true, true, true);
//-----------------------------------------------------------------------------------------------------------------------
And yes, you need mask with information in alpha channel:
1) It's can be done with GIMP (very simple, but required GIMP knowlege).
2) You can write you own rootine, for pushing color information to alpha channel, before mask texture creation (it's very simple - just few lines of code).
3) Or just use GL_ALPHA "format" attribute in glTexImage2D for mask texture. This flag just writes bitmaps color to texture alpha channel.
What language or technology would I need to be able to create documents online? I want to be able to add text and images and move them into position, resize etc, similar to this.
And then when complete, create a PDF from them.
Sorry if this is a bit vague, I just need to know where to start researching.
You need to decide on your basic technology: Flash, Silverlight, Canvas, client-side SVG, server-side SVG or server-side bitmap. There are also commercial solutions that work with Adobe InDesign documents (and probably a host of other proprietary formats) but I'd expect those not to be cheap.
Flash/Silverlight require plugins, and are considered by some to be a dying technology - though I am sure that is disputed. Canvas is 'very HTML5' and is essentially a bitmap built/rendered on the client, but if you are ultimated rendering to PDF it may not provide the resolution you need. The same limitation affects building an image server-side too - you should probably be dealing with vector elements plus bitmaps, rather than rendering everything to pixels as you go.
That leaves SVG in my list, either on the client (see RaphaelJS) or on the server (see Inkscape). I'm doing some work with server-side SVG rendering at the moment, and it is promising; although subject to more scalability issues than client-side, it doesn't suffer from browser-compatibility issues or the limitations of browser rendering.
The biggest issue in browser SVG rendering is flowed paragraph text and text in/on a path - I am not sure how well these are implemented in modern browsers, or how much agreement there is between them. This is especially the case given that some of these require SVG1.2, and browsers (afaik) are only just settling on SVG1.1, after many years. But, if you just want to do standard blocks of text, bitmaps and vector elements, browser-based SVG should suit you fine.
The example you've given uses a server-side technology (SVG, or perhaps a commercial format) and renders to low-res PNG on the client.
In your case, once you've considered how to 'do the editing', you'll need to consider how to render to PDF, which will be done on the server. You could go low-level and use something like FPDF, use a report renderer like Jasper, or use a graphics system like GhostScript, Inkscape, Scribus, ps2pdf, svg2pdf etc.
Aside: I normally don't answer questions without obvious prior research. But, since you've indicated that you will indeed undertake this, I'm happy to help get you started.
I am writing a DLL that needs to do some work in Cuda 3.2 and some work in OpenGL. OpenGL will render some grayscale images that my Cuda code needs to read in and modify, and then give back to OpenGL as a texture. I believe I need to create PBOs to do that. I have done some basic OpenGL stuff before but never worked with extensions, and that's where my problem is - I've been searching for 2 days and so far haven't been able to find a working example, despite wading through pages and pages of code. None of the samples I've tried work (and I'm sure my vid card will support it, being a GTX470)
Some specific questions:
1. I installed the nvidia opengl sdk. Should I be using glew.h and wglew.h to access the extensions?
2. My DLL does not have any UI - do I need to create a hidden window or is there an easier way to create an off-screen rendering context?
3. Can I create a grayscale PBO by using GL_RED_8UI format? Will both cuda and gl be happy with that? I read the opengl interop section in the cuda programming manual and it said GL_RGBA_8UI was only usable by pixel shaders because it was an OpenGL 3.0 feature, but I didn't know if that applied to a 1-channel format. 1 channel float would also work for my purposes.
4. I thought this would be fairly easy to do - does it really require hundreds of lines of code?
Edit:
I have code to create an OpenGL context attached to a HBITMAP. Should I create a bitmap-rendering context and then try to attach a PBO to that? Or will that slow me down by also rendering to CPU memory? Is it better to create an invisible window and attach the PBO to that? Also, does the pixel format of my PBO have to match the window/bitmap? What about the dimensions?
Thanks,
Alex
There's actually an example of how to use OpenGL and CUDA together. Look at the SimpleGL example.
You may want to take a look at this example:
https://github.com/nvpro-samples/gl_cuda_interop_pingpong_st
See here: http://code.google.com/p/ie7-js/
Does anyone have any experience or remarks about this javascript? Is it worth including? Do you recommend it?
I know many people, myself included that are using various IE hacks to get transparent PNG support. THis looks like a little bit more help, and as long as it works, and the size is fairly small, I wouldn't see much against using it.
I've used it before, and my results are mixed. Those scripts cause IE to churn for a bit on page load. Basically, you have to think of it as iterating through Elements and stylesheet rules to apply "fixes" for areas that are deficient in that particular rendering engine. In some cases, depending on how complicated your markup or stylesheets are, that can take a bit of time and you will see the browser hang.
That said, if you can trade off that performance cost, you will save development time as you'll spend less time hacking around IE6 quirks; IE7/IE8 will provide enough missing functionality that you can avoid certain edge cases, can develop using standards better (min-width/min-height, multiple className selectors, etc.), and certain rendering issues will disappear.
However, if you just need 24-bit transparent PNG support, use a tool built for that. Including IE7/IE8.js for PNG support alone is like pounding in a nail with a tank. Use DD_belatedPNG for that.
It works, but its worth keeping in mind that ie7.js and ie8.js do much more than provide transparent PNG support. Even with the transparent PNG support, its worth keeping in mind that transparent background images cannot be tiled (repeated) using background-repeat or positioned using background-position. This hinders any ability to use CSS rollovers using background-position. I've only used it on one site I've done, and now that I'm updating the site I can't remove the ie8.js because if I do the entire website breaks layout in IE. I don't believe I'll be using it in the future, and instead rely on simple CSS hacks or simply allow my sites to "degrade gracefully" in IE6.
I know that there are some tools for fixing the transparent PNG problem which are more flexible than this. For instance, the jQuery plugin ifixpng2 will support background position, which ie7-js doesn't do.
As long as you are aware of exactly what it fixes, I would say go for it. I'm not sure about this lib exactly, but some libs get very expensive if you have a large DOM, as they tend to hook in HTC file base behaviors on EVERY DOM Element. This causes the dreaded "Loading x of y" status bar message to flash constantly on the initial load, and any newly generated DOM content.
well its beautiful and works grate way u can use cs3 features like li:hover. we did lost of project last time using ie8.js and it works great way.