I'm trying to draw a sprite in libgdx that has a transparent background to it, but the transparent background is filled in with white instead of showing what has already been rendered at that location.
The sprite (with the hat) is 64 by 64 with transparency around the edge and on the right. There should be two tiles with a 'C!' behind him but it's just filled in with white.
This is the code I am using to render the image.
public void draw(SpriteBatch sb, float parentAlpha){
sb.enableBlending();
sb.draw(texture, getX() + 32, getY());
}
If you're going to enable blending, you also need to set the blend function with setBlendFunction. This defines exactly how you want the blending to work. Presumably, you want the classic GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA blending.
All the sprites are supposed to be blended? Maybe disabling the blend after you already drawn could solve your problem.
Maybe something like that:
public void draw(SpriteBatch sb, float parentAlpha){
sb.enableBlending();
sb.draw(texture, getX() + 32, getY());
sb.disableBlending();
}
If this doesn't work you could try activating the blend in the GL options with something like that:
Gdx.gl.glEnable(GL10.GL_BLEND);
Gdx.gl.glBlendFunc(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA);
...
Your code Here
...
Gdx.gl.glDisable(GL10.GL_BLEND);
Hope it helps :)
First, make sure your PNG has transparency information in it.
Second, make sure you're drawing things in the right order (you have to draw the background boxes before the sprite).
I managed to fix the problem by changing my application to OpenGL 2.0 instead of 1.0. Still not sure what the problem was.
Related
I am using the LibGDX orthographic camera class to handle different screen sizes and it works pretty well for me. The only issue I have is the border around the screen when the device doesn't stretch to scale.
I don't mind a border that much, the only thing that bothers me is the color of the border. I think it would look much nicer if it was black instead of white. Any way to change that?
Also I posted another question about android touch handling that was never answered. If someone could answer that, that would be great. I don't want to have to ask it again, I don't want to seem spammy. My Question
When your camera view is smaller than screen you probably just need to change clear color of GL.
glClearColor(r, g, b, a);
glClear(GL_COLOR_BUFFER_BIT);
glClearColor(0,0,0,1);
Black clear screen. Thats all you need.
I'm using SVG files in my Game and i want to add transparency and brightness effects to them. So what i want is that a sprite becomes more and more transparent until it's invisible. This looks much smoother than a just disappearing sprite. This allows also smooth transitions between the levels where a white screen gets less transparent and then again more. I hope you understand what i mean. Besides this a brightness effect would be nice, too. A sprite can get brighter or darker during the game. Nevertheless i could create a workaround for this using the transparency effect, but yeah, i have none :/
I use this library:
https://androidsvg.googlecode.com/hg/doc/reference/packages.html
I render my svgs on this way:
svg.renderToCanvas(pCanvas);
However i can also convert it to pictures:
Picture pic = svg.renderToPicture();
Maybe this information will help you.
Does there exist something what could help me? And if not, have you an idea how can i solve the problem?
EDIT:So iwant my SVGs behave like these ones:
http://scratch.mit.edu/projects/24634091/
You could use an ImageView and setAlpha(), as Frank says. Or it may just be easier to render the sprites to the canvas in your draw() method.
If you are writing a game, then you may find that rendering SVGs in your game loop may not be fast enough. So you might have to pre-render all your SVG sprites to Bitmaps (ie on startup) and draw them to your Canvas.
Paint p = new Paint();
p.setAlpha(alpha);
canvas.drawBitmap(sprite, x,y, p);
So I am developing a small Pong replica simply for some practice with LWJGL. Since there is no easy way to write customizable text in LWJGL, I am using textures for the start button, other buttons, and so on. However, when I drew the texture, it turned out to be discolored on my purple background. If I change the background to white, there is no discoloration. Help?
Also, my start button texture is something like 50x22, but I put it on a 64x64 image because Slick can only load resolutions that are an exponent of two. I adjusted the rectangle being drawn so that it is not warped, and the rest of the image is transparent, so it shouldn't be visible once I sort out the above problem. Are there any alternatives to my method?
This is where I initialize my OpenGL stuff:
public static void setCamera()
{
glClear(GL_COLOR_BUFFER_BIT);
glEnable(GL_TEXTURE_2D);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0,width,0,height,-1,1);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
And this is where I draw the texture:
public void draw()
{
logic();
glPushMatrix();
glTranslated(x,y,0);
texture.bind();
glBegin(GL_QUADS);
glTexCoord2d(0,1); glVertex2d(0,-196.875);
glTexCoord2d(1,1); glVertex2d(width+18.75,-196.875);
glTexCoord2d(1,0); glVertex2d(width+18.75,height);
glTexCoord2d(0,0); glVertex2d(0,height);
glEnd();
glPopMatrix();
}
Thanks :)
As discussed in comments, your initial problem was that you had neglected to reset the "current color" before drawing your texture. GL is a glorified state machine, it will continue to use the color you set for every other draw operation... so setting glColor3d (...) when you drew your background also affects your foreground image.
Adding the following before drawing your textured quad will fix this problem:
glColor3f (1.0f, 1.0f, 1.0f);
However, you have brought up a new issue in your comments related to blending. This question boils down to a lack of a blending function. By default when you draw something in OpenGL it will merely overwrite anything else in the framebuffer.
What you need for transparency to work is enable blending and use this function:
glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
This effectively does the following:
NewColor = (NewColor.RGB * NewColor.A) + OldColor.RGB * (1.0 - NewColor.A)
With this, the parts of your texture that have an alpha value != 1.0 will be a mix of whatever was already in the framebuffer and what you just drew.
Remember to enable blending before you draw your transparent objects:
glEnable (GL_BLEND);
and disable it when you do not need it:
glDisable (GL_BLEND);
Lastly, you should be aware that the order you draw translucent objects in OpenGL is pretty important. Opaque objects (such as your background) need to be drawn first. In general, you need to draw things from back-to-front in order for alpha blending to function correctly. This is the opposite order you would ideally want for opaque geometry (since hardware can skip shading for obstructed objects if you draw objects in front of them first).
SpriteBatch.SetProjectionMatrix(cam.combined) makes Spritebatch not draw blocks and my character but camera movement works, but if I don't use this line of code everything is drawn but camera is not working? Does anyone know the solution, because if simply can't see it.
EDIT: sorry for the messy first post
Here is the piece of code that is troublesome:
public void render()
{
cam.update();
spriteBatch.setProjectionMatrix(cam.combined);
spriteBatch.begin();
drawBlocks();
drawBob();
spriteBatch.end();
cam.position.x = world.bob.GetPosition().x;
cam.update();
drawCollisionBlocks();
if(debug)
drawDebug();
}
I found the solution but for anyone who may have this kind of problem in the future, the problem was in drawing methods where i was drawing
textures like this:
CODE:
spriteBatch.draw(bobFrame, bob.GetPosition().x * PPuX, bob.GetPosition().y*PPuY ,Bob.SIZE*PPuX , Bob.SIZE*PPuY );
PPuX,PPuY were of type int and were used for different screen sizes and that was messing spriteBatch up when i was setting the projection matrix
The spriteBatch.setProjectionMatrix(cam.combined) lets spriteBatch use the coordinate system that specified by cam instead of the default ones. This is because the both's coordinate system are different and the cam.combined will do the maths for you.
I believe you actually ARE drawing the sprites, however you are not seeing them because your camera viewports are not set(ie. you are looking at the wrong coordinate area).
Adding
cam.setToOrtho(false); //true to invert y axis
"Sets this camera to an orthographic projection using a viewport fitting the screen resolution, centered at (Gdx.graphics.getWidth()/2, Gdx.graphics.getHeight()/2), with the y-axis pointing up or down."
Link to JavaDOC here
I have image inside the JPanel. I would like to rotate the image. Is it possible to rotate the JPanel using Graphics, Image is rotatable, Just out of curiosity is it possible to rotate JPanel ?
Yes! This is possible and fairly straightforward too. I haven't done rotations but I have done other affine transformations (scaling the entire GUI up and down) very successfully on a project. I cannot see why rotations should be any different.
Instead of trying to scale each component use the fact that you can set a transformation on the Graphics object. Since this is shared between all components being rendered you get all things transformed at once "for free". It is important to realize that the transformation is only a rendering-process-step ... i.e. all components still believe they have the bounds (locations+sizes) which you gave them in the untransformed world. This leaves us with the challenge to deal with mouse-events correctly. To do this you simply add a glass-pane in front of your main-panel. This pane collects all mouse-events and apply a reverse of the transform on the event and then sends the event onward towards all other components.
Conceptually very simple! Still, I remember it took some tweaking to get it all crisp though. Especially the fact that rendered texts (fonts) in java are not correctly linearly scaled (it scales in discrete steps corresponding to font-sizes) imposed a final challenge in my scale-affine-transformation-case. Maybe you don't have to worry about that if you only rotate.
I got my inspiration from JXTransformer: http://www.java.net/blog/alexfromsun/archive/2006/07/jxtransformer_t.html
As far as I know you can't rotate a JPanel itself but you might be able to rotate the image inside the JPanel using Java2D. Here's an article that might help.
Edit:
There might actually be a way to rotate JComponents (such as JPanel) if you override their paintXxx methods and use AffineTransform.
It's not possible to rotate JPanel itself, but it's certainly possible to rotate any image inside. There are quite a few ways to do that, you can - for example - override JPanel's public void paint(Graphics g) and then cast Graphics to Graphics2D. It's very useful class, does rotation and much more ;) Check api docs for more info about this one.
Yes, it is possible. But you won't rotate the panel, but the image:
public void paintComponent(Graphics gg)
{
Graphics2D g = (Graphics2D) gg;
g.setRenderingHint(RenderingHints.KEY_ANTI_ALIAS, RenderingHints.VALUE_ANTI_ALIAS_ON);
AfflineTransform matrix = g.getTransform(); // Backup
float angle = Math.PI / 4.0f; // 45°
g.rotate(angle);
/* Begin */
g.drawImage(yourImage, [your coordinates], null);
/* End */
g.setTranform(matrix); // Restore
}
Everything between /* Begin */ and /* End */ will be drawn rotated.
(I didn't test the code, so, they may be some syntax errors...)