I have previously worked on gltf 1.0 and is now trying to update my application to render gltf2.0 sample models provided by khronos. I understand that shaders(glsl) and techniques are no longer part of the core properties in gltf 2.0.
So my question is that:
Are shader information now separated from .gltf? I know there is KHR_technique_webgl extensions which consist of the technique and shader properties(exactly like how gltf1.0 represent shader), are we suppose to be use that if our material arent pbr?
How do rendering engines now grab shader information from normal .gltf now(without the extensions)? Do we do it like old school way ie loading our own shader and manually map the model attributes to shaders attribute?
The KHR_technique_webgl extension will eventually be finished, and will provide a way to include custom shaders with your glTF2.0 model. But as of this writing, the extension is not fully defined and tools cannot implement it.
The more general case (and recommended if it suits your needs) would be to use PBR or Blinn-Phong materials. These are declared abstractly in glTF, so that rendering engines can build their own shaders for these material types, and will generally integrate better with engines' own lighting and/or shadows.
Related
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.
Despite reading through much of Apple's docs and reading through their forums and watching their WWDC videos, I seem to have missed the steps required to utilise the texture packing and performance of Sprite Kit for making many large-ish Sprites.
Imagine 100 different sprite images, for 100 different sprites. If each image is 256x256 pixels, they're going to take up more than one SpriteSheet at 2048x2048. And let's imagine that's the limit, rather than 4096x4096, just so it's understood that more than one spritesheet is going to be required.
There might be as many as 20 different sprites on screen at any given time. So performance is a consideration.
How to import these images and then create these sprites in the manner SpriteKit intends for its texture packing and performance considerations of in game use?
Just a specific link to Apple recommended absolute steps will be fine. I must have just skimmed right over it.
Apple's new docs go this far:
Which completely fails to convey:
Import folder, or images?
Import to WHERE within the project?
Load and reference them, how?
So let me see if I can reasonably answer your question. Please keep in mind that while I have used SpriteKit, I'm not a big fan of it. And when I did use it, I did not use any of the tools Apple provided (eg. SKTextureAtlas, sks files, etc). Nevertheless, this should still be applicable. Best practices as per Apple? I have no idea.
Question: Import folder, or images?
If you use Xcode's means of generating atlases, you Add Files... to your project a folder named XYZ.atlas, where XYZ will be the texture name. This folder contains all of your textures which will be in the atlas.
Question: Import to WHERE within the project?
Just has to be in your project. But you should have some organization Group hierarchy in your project file.
Question: Load and reference them, how?
An example of loading would be something like (yeah, I know boo, Obj-C):
self.myTextureAtlas = [SKTextureAtlas atlasNamed:#"MyTexture"];
Inevitably, you will want access to the actual textures and you'll need to do something like:
self.tex0 = [self.myTextureAtlas textureNamed:#"tex0"];
A good tutorial is here: https://www.raywenderlich.com/45152/sprite-kit-tutorial-animations-and-texture-atlases
Here is also a screenshot that shows the .atlas folder. It also shows a couple of tool generated atlas files.
So here you can see I have 2 Groups which are references to folder MyTexture.atlas and ProgressBar.atlas. In game, they will be called MyTexture and ProgressBar.
I have also included, just as an example the same atlases, but pre-built. You would not have both in your project, I only used it to show what including a pre-built would loo like. I generated them using TexturePacker. I'll get into why this may be a better option later on. TexturePacker also can create SpriteKit atlases instead of the atlas PNG.
In reality, an atlas is really just a texture with sub-textures are associated with it. The sub-textures are X/Y/W/H sections of the texture. The actual memory for the texture is "held" by the atlas. Understanding what an atlas is is a useful thing, because it allows you to think through how you would support it if you had to implement it yourself. Or enhance it.
Now let's go over how you would use this altogether to do something useful.And for this you're going to need a texture manager (aka TextureManager), sprite manager (aka SpriteManager) and a manifest of some sort.
The manifest is really some form of association between "sprite name" to atlas:sub texture pair. For example:
{
"progressbar": {
"atlas": "ProgressBar",
"subtexture": progressbarbacking"
},
"progressbarfillr": {
"atlas": "ProgressBar",
"subtexture": progressbarfillr"
}
}
In this case it is some JSON, but you can have whatever format you want. When I build my games, I have a build assets phase which generates all my textures and from that, builds a manifest. This manifest tells me not only what textures exist, but is used later on to find the correct association of a "sprite name" to the actual atlas and sub texture. "sprite name" is just some name you have associated meaning. It could be "zombie" for example.
You use a TextureManager as your asynchronous loader. In addition, it is your inventory manager of all your textures. As an inventory manager, it will prevent you from double loading textures and also give you the correct reference to textures/atlases when requested (if they exist).
You would use the SpriteManager to create a new SKSpriteNode using the data from the manifest. For example:
SKSpriteNode *progressBar = [[SpriteManager sharedInstance] createSprite:#"progressbar"];
Here I've made it a singleton. Use whatever implementation you want. If you hate singletons, that is fine, this is just an example. You'll note that it returns a SKSpriteNode. I see a lot of people making subclasses from SKSpriteNodes. I never do this. To me, the graphic component is always a "has a". However, if you are doing an "is a", you can still do this. You just need to feed in the class you need. I'm considering the way of handling that out of scope for this question.
Now if you look at the manifest, you'll notice that progressbar is associated with an atlas named ProgressBar and a sub texture named progressbarbacking. To get the texture you need, you'd have some implementation code in SpriteManager like:
// NOTE the literal names would be variables which contained the unpacked association from progressbar
// literal strings are used to make the idea easier to follow
SKTextureAtlas *atlas = [[TextureMaanger sharedInstance] findAtlasNamed:#"ProgressBar"];
//Error check of course
SKTexture *tex = [atlas textureNamed:#"progressbarbacking"];
// Error check of course
SKSpriteNode *sprite = [SKSpriteNode spriteNodeWithTexture:tex];
Or perhaps you would just have a call:
SKTexture *tex = [[TextureManager] sharedInstance] texNamed:#"progressbarbacking" atlas:#"ProgressBar"];
SKSpriteNode *sprite = [SKSpriteNode spriteNodeWithTexture:tex];
And there you have it. A means to get sprites from atlases.
Best practices as per Apple? Dunno, but it is along the lines of what I do.
Some people will complain that there will be dictionaries involved and some of this will be "slow". And yes, there is a penalty for this. And reality, I don't use a dictionary for this either, but it is easier to get the idea across as the dictionary. Also keep in mind that I consider the usage of this to occur during loading phases and very little during game play, if at all. One of the tricks to performant games is pre-loading all or as much of the data you need prior to actual game play.
Oh, going to why I pre-build the atlases. So part of your question was organization of textures to atlas. And that is why. I like to see the generated atlas and understand what the size is and what is in it. Additionally it makes downloadable atlases easier.
As an optimization, you would want to try and put textures in which are all drawn relatively the same time. For example, it would make sense to have all HUD items in the same atlas versus mixing HUD with background.
I have some code in .fx file whening using fxcomposer,and I met some code like this:
float4x4 WorldITXf : WorldInverseTranspose < string UIWidget="None"; >
what is the < and > containning meaning?
< string UIWidget="None"; > is an annotation that is not used by the HLSL complier or Direct3D. It's just used by FXComposer to determine how to provide interactive controls for the shader in tools.
It's an aspect of the legacy Direct3D 9 era Effects system, and was intended to make it easier for Digital Content Creation (DCC) tools like FXComposer, RenderMonkey, Autodesk 3DS MAX, etc. to provide more art-driven UI for controlling shader behavior.
More modern solutions for art-driven shader production have moved away from just having a programmer mark up a shader with 'tweaks', and are more often done with flow diagrams like Visual Studio's Shader Designer--although VS's solution here is not nearly as robust as say the visual shader designer in Unreal Engine.
See MSDN
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
In XNA, how do I load in a texture or mesh from a file without using the content pipeline?
The .FromFile method will not work on xbox or zune. You have two choices:
Just use the content pipeline ... on xbox or zune (if you care about them), you can't have user-supplied content anyways, so it doesn't matter if you only use the content pipeline.
Write code to load the texture (using .SetData), or of course to parse the model file and load the appropriate vertexbuffers, etc.
For anyone interested in loading a model from a file check out this tutorial:
http://creators.xna.com/en-us/sample/winforms_series2
This is a windows only Way to load a texture without loading it through the pipeline, As Cory stated above, all content must be compiled before loading it on the Xbox, and Zune.
Texture2D texture = Texture2D.FromFile(GraphicsDeviceManager.GraphicsDevice, #Location of your Texture Here.png);
I believe Texture2D.FromFile(); is what you are looking for.
It does not look like you can do this with a Model though.
http://msdn.microsoft.com/en-us/library/microsoft.xna.framework.graphics.texture2d.fromfile.aspx
If you really want to load an Xna Xna.Framework.Graphics.Model on PC without the content pipeline (eg for user generated content), there is a way. I used SlimDX to load an X file, and avoid the parsing code, the some reflection tricks to instantiate the Model (it is sealed and has a private constructor so wasn't meant to be extended or customised). See here: http://contenttracker.codeplex.com/SourceControl/changeset/view/20704#346981