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How to create a 2D sprite animation in OpenGL 4?
I’m currently trying to setup a 2D sprite animation with OpenGL 4. For example, I’ve designed a ball smoothly rotating with Gimp. There are about 32 frames ( 8 frames on 4 rows). I aim to create a sprite atlas within a 2D texture and store my sprite data in buffers (VBO).
How to generate a texture in OpenGL ES?
First step would be to get a bitmap to generate a texture from. You can get hold of a bitmap in many different ways from downloading, generating or simply just load one from the resources.
How are sprite tiles stored in the shader?
As the sprite tiles are stored on several rows if appears to be difficult to manage it in the shader. Not really, all your sprites are the same size, so you get a perfect uniform grid, and going from some 1D index to 2D is just a matter of division and modulo.
What does GL _ clamp to edge do in OpenGL?
We use the glTexParameterf function to tell OpenGL what to do with the texture. By default OpenGL uses something called GL_REPEAT. GL_REPEAT means that OpenGL should repeat the texture beyond 1.0. GL_CLAMP_TO_EDGE means that OpenGL only will draw the image once and after that just repeat the last pixel line the rest of the image.
How to make a VBO with 2D sprites?
Create a VBO with 32 (frame squares)*2 (triangles per frame square)*3 (triangle vertices)*5 (x,y,z, u,v per vertex) = 960 floats of space. Fill it in with the vertices of all your sprites in a 2 triangler-per frame fashion.
What’s the best way to animate a 2D image?
Otherwise you have it in RAM and GPU memory, which does not make a lot of sense. Another thing you could do is to use different animation techniques like keyframes or skeletal animation (also a valid approach in 2D) to move sprites around instead of saving an extra image/sprite for each state.
How to change the coordinates of sprite tiles?
My sprite rectangle would be always the same ( i.e. rect (0,0,32,32) ) but my texture coordinates will change each time the frame index is incremented. I wonder how to modify the coordinates. As the sprite tiles are stored on several rows if appears to be difficult to manage it in the shader.
How to use gldisable2d function in OpenGL?
To use these functions, simply call glEnable2D () before you start rendering 2D and after you do any 3D rendering (if any). Then when you are done with your 2D rendering, simply call glDisable2D () before you render the final scene or frame.
How to make a 3D weapon in OpenGL?
For the overlaying of the 2D weapon, you can use glOrtho for the camera view. You create a 3d quad and map the .png-based texture to it. You can make the quad face whatever direction you want, as in the first picture, or make it always facing the camera (like a billboard, mentioned by Svenstaro) as in your second picture.
Can you make 2D sprites in a 3D world?
Just about any 3D engine should be able to do them by default. Ogre3D can do it, for instance. That’s not really 2D sprites. Those men seem to be rendered as single quads with a texture with some kind of transparency (either alpha test or alpha blending).