I'm wanting to build a game with some simple effects.
I want to add the warping effect that you see in games like geometry wars and geodefence. I know how to implement this effect in OpenGL ES. Would I be able to add this to a Cocos2D created app?
I want to have a 3D model that only moves on a 2D plane. It may rotate. First, can I add OpenGL shading to the model? Second, can I have Box2D physics applied to it like it was a 2D sprite?
That's about it. Those are the main functionality I'm hoping I can add to a Cocos2D application and am trying to figure out if I can before I spend a lot of time learning how to use the game engine.
1) Yes, you can intermix Cocos2D and OpenGL ES together - you can override the CCNode's "draw" method and do just about anything you'd like in there (such as rotating, scaling, etc in OpenGL with the texture).
2) You can add the model, and you can shade the model - yes. If you create the body fixtures for the model from Box2D, but treat the Model as if it were a '2d sprite' (has set width/height) - yes, you can use Box2D - but understand that it will only react within the 2D Physics World, and won't have any depth applied to it.
It should be noted though, that though these are possible, you will still need to implement the code to do so on your own.
Related
Hello recently i started to mess around with SDL. Since i was interested in some 2D/2.5D games.So i started messing around with SDL in C++, I was looking to recreate something similar to Original Zelda.
So as far as i understand those game work with some kind of isometric prespective, or standard Orthogonal view but one thing i do not understand is how can you generate 3D-like Collisions between those objects on the map (tiles, sprites etc which are in 2D). Have a look at the video link below. Is this created purely in SDL, is it PerPixel collision or rectangular ? Or it might involve OpenGL as well ?
Link: https://www.youtube.com/watch?v=wFvAByqAuk0
The original was probably a simple Rectangular collision.
I believe that your "3D collision" is the partial collision present in some objects. For example, Link can go through the leaves, but not through the trunk.
You can do it easily in 2 ways:
Layers of rendering and collision. The trunk is located in one layer and is covered by some collision boxes. Link is present in a intermediary layer. And the leaves are in another layer, on top of Link. Then you can check collision between Link's Layer and the layer with the trunk and other objects, for example.
Additionally you can create a property for your tiles in which you can store the type of collision you hope to obtain. For example, 'box' collision will tell your engine that the object is collidable on every side. Or 'bottom' collision will tell your engine that Link will collide with this object only if he is walking down into the object (this is the effect of you will see on some 2D sidescrollers: jump through a tile but then fall into it solid.
Per pixel collision in those simple cases is not worth it. I find it much better to personalize the collision ourselves, using creativity, masks and layers.
BTW: This topic would fit better on https://gamedev.stackexchange.com/
If I want a 3D animated/rigged character in OpenGL game how i would have it in OpenGL?If i make a animated/rigged character in 3Ds max is it possible to have that character in OpenGl?would be helpful if someone gives a proper way or a tutorial link to export animated model from 3d software to open GL
OpenGL is a very simple 3D framework which only offers the bare bones. OpenGL can display triangles and fill them with color and that's about it. It comes with some helper functions to manipulate point clouds but it's really very basic.
Animation and rigging are way beyond what it can do. What you need is a framework which supports animation and rigging which then uses OpenGL to display the result.
Since you don't specify any requirements, it's hard to say which one would be good for you. Blender is probably a good place to start. It's game engine runs on many platforms, supports OpenGL, animation and rigging.
In my case, I'm making a 2D game that camera always follow my character, but there will be scene limitations so I have to stop follow him when he is nearly beside scene borders. I also have to treat camera scale, so I have to decide whether to use CCFollow::actionWithTarget() or CCCamera.
In CCCamera.h it says:
Limitations:
- Some nodes, like CCParallaxNode, CCParticle uses world node coordinates, and they won't work properly if you move them (or any of their ancestors)
using the camera.
- It doesn't work on batched nodes like CCSprite objects when they are parented to a CCSpriteBatchNode object.
- It is recommended to use it ONLY if you are going to create 3D effects. For 2D effecs, use the action CCFollow or position/scale/rotate.
The last sentence is interesting, why ONLY use it in 3D effects? Seems CCCamera is not recommended by its producer. I know it's a shortcut to treat camera movements, but I just don't know why better not to use it in 2D games.
If you notice, the CCCamera.h file also says:
Useful to look at the object from different views.
The OpenGL gluLookAt() function is used to locate the
camera.
There's a good write up in the OpenGL Redbook on how the camera works. My understanding is, the camera is meant to setup the initial orientation, then you move the world by updating the model matrix (which is what I'm guessing CCFollow does for you). There's an answer here that may help if you still want to use the camera:
moving CCCamera
I'm working on an Augmented Reality project that uses multiple markers to get positions for 3D models that I'm planning to overlay. (I'm doing this from scratch using OpenCV and I'm not using ARToolkit or any other off the shelf marker detection libraries).
Environment: Visual C++ 2008, Windows 7, Core2Duo 1GB ram, OpenCV 2.3
I want the 3D models to be manipulated by user so it will turn out to a sort of simulation.
For this I'm planning to use OpenGL. What are your suggestions, recommendations? Can the simulation part be done by using OpenGL itself or will i need to use something like OpenSceneGraph/ODE/Unity 3D/Ogre 3D?
This is for an academic project so better if I can produce more self-coded system rather than using off-the-shelf products.
it would seem that OpenGL is pretty enough for your needs (drawing a model with a specific colour and size).
If you're new to OpenGL, and you are not going to be using it for your future projects, it might be easier to use the old fixed-function pipeline, which already has the lighting and color system ready and doesn't require you to learn how to write shaders.
For your project, you will need a texture where you would copy the image from camera using glTexSubImage2D() which you would in turn draw to background (or you can use glDrawPixels() in case you don't require any scaling). After that, you need to have your model, complete with normals for lighting. Models can be eg. exported from Blender or 3DS Max to ascii format, which is pretty easy to parse. Then you can draw the model. Colors can be changed using glColor3f() before drawing the model (make sure you don't specify different color while drawing the model). Positioning of the models is done using matrices. The old OpenGL have some handy and easy-to-use functions for rotating and translating objects. There are also functions for scaling the objects (changing size), so that is covered pretty easy. All you need is to figure out camera position, relative to the marker (which i believe is implemented in OpenCV).
If you were to use the forward-compatible OpenGL, you would need to set up vertex buffer objects to contain model data and write vertex and fragment shaders to shade and display your model. That's kinda more work for which you get extended flexibility. But you can use shaders in the old OpenGL as well, if you decide you need them (eg. for some special effects).
Learning how to use a scenegraph or an engine (ogre) can take some time, i would not recommend it for your task.
If I have a human body 3d model, that I want to animate walking, what is the best way to achieve this? Here are the possible ways I see this being implemented:
Create several models with the legs in different positions and then interpolate between these models.
Load the model into openGL, and somehow figure which vertices correspond to the legs and perform the appropriate transformations.
Implement a skeleton or armature (similar to this: blender animation wiki).
Technique that you described in the first option is called morph target animation and often used for some detailes of animation like facial animation or maybe opening and closing of hands.
Second option is procedural or physical animation which works something like robotics where you give the body of your character some velocity to move forward and calculate what legs need to do for it to avoid falling. But you wouldn't do it directly on vertices, but on skeleton. See next one.
Third option is skeletal animation which animates skeleton and the vertices follow it by the set of rules. Attaching vertices to skeleton is called skinning.
I suggest that, after getting hang of opengl stuff (viewing and positioning models in space, camera, etc), you start with skeletal animation.
You will need a rigged and animated model for your 3d app of choice. Then you can write an exporter to your custom format or choose a format that you want to read from your app. That file format should contain description of the model, skeleton, skinning and key frames. Than you read and use that data from your code to build the mesh, skeleton and animate over key frames.
If I were you, I'd download Blender from http://www.blender.org and work through some animation tutorials. For example, this one:
http://wiki.blender.org/index.php/Doc:Tutorials/Animation/BSoD/Character_Animation
Having done that, you can then export your model and animations using e.g. the Ogre exporter. I think this is the latest version, but check to make sure:
http://www.ogre3d.org/tikiwiki/Blender+Exporter&structure=Tools
From there, you just need to write the C++ code to load everything in, interpolate between keyframes, etc. I have code I can show you for this if you're interested.