Basically what I want to achieve is a sprite highlight animation effect as displayed below.
The idea is that the white-translucent gradient sprite moves on top of the other sprite (left-to-right), using a blend mode like Overlay (Photoshop). The difficult part is that the top gradient sprite should only be drawn on the visible pixels of the sprite underneath. The other part of the gradient overlay should be discarded to not affect the background or other sprites underneath (like on the image to the far right).
Is it possible to achieve that effect with a clever combination of OpenGL blend modes and how, or would I have to create a custom shader to combine these sprites?
Background: I'm using libgdx with OpenGL ES 2.0 and the app runs on Desktop, Android and iOS.
There arę many ways to do it. The simplest one:
You should render button and hilight in a single pass. In fragment shader, after sampling button texture and hilight texture calc the output color as for blending (could be mix(c1,c2,c2.a)) and alpha as button texture alpha only. Of course enable blending in usual way: (srcalpha,1-srcalpha)
Related
I have a texture and I want to draw it to a FrameBufferObject. The texture has transparent areas. I would like the following:
For all transparent pixels, let them be drawn transparent in the FrameBufferObject.
For all non-transparent pixels, let them be drawn using a color of my choosing, ie pure red (ignore their actual rgb value)
I've tried Batch.setColor(red) before drawing the texture, but that just tints it - I want all non-transparent pixels to be drawn pure red.
I am also trying to figure out how to achieve this in just opengl directly, looks like there may be a way to do this with blending, which can then be related back to gdx.
Thanks
You need to write a shader and the shader is the OpenGL program that renders the texture. So your shader would render transparency without change and all else would the color of your own choosing.
The following link has libgdx shaders for palette swapping i.e. direct reassignment of color at render, which you can easily adapt for single color and transparency.
https://www.javaer101.com/en/article/12241616.html
I'm using a prefab for a box shape, which has a front and back plane.
My images are PNG and have transparent areas around the edge. I dragged the image onto my front plane, which now has a drop-down box for "Shader".
First I chose Shader: "Standard" but the transparent areas of my PNG image weren't transparent, so in order to fix that I changed it to "Sprites / Diffuse"... now the image looks fine (from the front).
However, when I rotate the shape, the image is also visible from the back. I want a way to not see the image / texture from the back.
How can I make the images only visible from the front side of a plane, whilst also preserving the transparency areas of the image / texture?
If you are using the standard built-in shader, you need to set the rendering mode to transparent in order for the texture's alpha channel to be transparent. The sprite shader, by default, forces the rendering of otherwise invisible back-faces, whereas the standard shader does not.
I have managed to animate a series of sprites by dragging a group of sprites into the Hierarchy. However, when I enabled the Canvas, the Canvas was blocking all the sprites. What should I do to display the animation on the Canvas? I have tried adjusting the layers and camera modes, but to no avail.
I'm not sure if I understood your question correctly, but I understand that you want your sprites to be displayed on top of the UI. You can use 2 cameras and adjust their depths so that one of them displays the layer of the animation (make this one the top camera) and the other one displays the UI layer.
Use Culling Masks in Camera
How to use Multiple Cameras
I'm using sprites for an animated menu in my game.
I tried two methods:
Image Renderer: Replacing the image per frame with the sprite slice in the animation window
Sprite Renderer: Same method
I'm playing the sprite animation with no loop then rotating the transform on the z-axis.
The problem is that with the image the Screen Space overlay works well but the rotation of the transform causes the sprite to look glitchy and rough. With the sprite renderer however the Screen Space must be put to Camera and the sprites get placed between other assets in the world.
Example: http://postimg.org/image/436q9jvax/
Is there a way to either fix the roughness on the rotation using image or force the Camera Screen Space on top? My only concern with the 2nd option would be in relation to responsiveness for multiple devices.
The easiest fix was to apply "sorting layers" to the canvas with the sprite renderers on to keep it on top.
I did however incorporate #beuzel's idea about separate cameras in the end and opted for 2D sprites with physics instead of a 3D rendered animation on canvas.
http://postimg.org/image/6qmtiirb9/
Thanks for making the good sample. A fix for the menu intersecting the world is using a seperate camera for the GUI layer. The rough animation might be a pixel perfect setting in the sprite rendering (just guessing).
I don't have enough reputation points to write this as a comment.
I am working on a simple painting app using LibGDX, and I am having trouble getting it to "paint" properly with the setup I am using. The way I am trying to do this is to draw with sprites, and add these individual sprites into a background texture, using LibGDX's FBO commands, when it is appropriate.
The problem I am having is something relating to blending, in that when the sprites are added to this texture that I am building, any transparent pixels of the sprite that are on top of pixels that have been drawn to previous will be brightened up substantially, which obviously doesn't look very good. The following is what the result looks like, using a circle with a green>red gradient as the "brush". The top row is part of the background texture now, while the bottom one is still in its purely sprite drawn form.
http://i238.photobucket.com/albums/ff307/Muriako/hmm.png
Basically, the transparent areas of each sprite are brightening anything below them, and I need to make them completely transparent. I have messed around with many different blending mode combinations and couldn't find one that was any better. GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA for example did not have this problem, but instead the transparent pixels of each sprite seem to be lowered in alpha and even take on some of the color from the layer below, which seemed even more annoying.
I will be happy to post any code snippets on request, but my code has become a bit of mess since I started trying to fix these problems, so I would rather only put up the necessary bits as necessary.
What order are you drawing the sprites in? Alpha blending only works with respect to pixels already in the target, so you have to draw all alpha-containing things (and everything "behind" them) in Z order to get the right result. I'm using .glBlendFunc(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA);