I have a 2D tile map in java (using libgdx no Tiled Map Editor) formed with squares and I want the tiles to gradually become darker until they won't be visible. So basically I don't want round light. The only option I know is to use alpha channel and make every tile from the source which is the player become less visible. I want to know how can I implement this using a shader. I want to render my map normally with a spritebacth and then apply the shader to my spritebacth, so I can render the light effect. Each tile should have it's own visibility. An example of a game which uses the kind of lightning I want is: http://www.desura.com/games/fragile-soul
Render each tile itself via SpriteBatch and use spriteBatch.setColor(r, g, b, a) with different "grey" values.
The tile where your player is standing on will start with white, so spriteBatch.setColor(1, 1, 1, 1) before rendering that one. And then linearly decrease the brightness for the other ones in a radius around.
For example all tiles one next to the player might get spriteBatch.setColor(0.8f, 0.8f, 0.8f, 1f) resulting in a slightly darker tile. You do this until you reach black via spriteBatch.setColor(0, 0, 0, 1). All those tiles will be completely black.
Related
I apologize for some of my ignorance as I am fairly new to Slick2D and LWJGL. Essentially what I'm trying to do is make a scene look like night time by covering it with a GL_QUADS rectangle that is tinted blue and is translucent.
That part is easy enough. What I want to do from there is draw triangles into this layer that vary the alpha channel so. The reason I want to do this is so I can simulate a light source by decreasing the opacity of the blue tinted rectangle as it gets closer to the light source.
I drew an example of what the expected result should be with the green being the background, the blue being the nighttime effect created by a blue tinted rectangle, and the increasingly dim light source in the center.
I need to find a way to do this with triangles because I created a raycasting algorithm that generates the result as a series of gradient triangles.
I apologize if this is explained poorly. I will answer any questions you might have.
Here is the chunk of code used to create the blue tinted rectangle:
glColor4f (0.0f,0.0f,1.0f,0.4f);
glBegin(GL_QUADS);
glVertex2f(0,0);
glVertex2f(screenWidth,0);
glVertex2f(screenWidth,screenHeight);
glVertex2f(0,screenHeight);
glEnd();
I would like to write a modified version of the following code to adjusted the alpha channel of that rectangle.
glBegin(GL_TRIANGLES);
setAlphaOfPriorLayer(0.0f);
glVertex2f(x1,y1);
setAlphaOfPriorLayer(0.4f);
glVertex2f(x2,y2);
setAlphaOfPriorLayer(0.4f);
glVertex2f(x3,y3);
glEnd();
Again, I'm using triangles to approximate a circle and allow for proper raycasting.
To achieve this, the use of a Frame Buffer Object is super useful. A FBO allows you to essentially render to a texture which can then be displayed on the screen. In my particular case, I rendered the elements to a FBO then used a shader while drawing it to the screen to get the desired opacities.
im trying do develop a Zelda like game. So far i am using bitmaps and everything runs smooth. At this point the camera of the hero is fixed, meaning, that he can be anywhere on the screen.
The problem with that is scaling. Supporting every device and keeping every in perfect sized rects doesnt seem to be that easy :D
To prevent that i need a moving camera. Than i can scale everything to be equally sized on every device. The hero would than be in the middle of the screen for the first step.
The working solution for that is
xCam += hero.moveX;
yCam += hero.moveY;
canvas.translate(xCam,yCam);
drawRoom();
canvas.restore();
drawHero();
I do it like this, because i dont wand to rearrange every tile in the game. I guess that could be too much processing on some devices. As i said, this works just fine. the hero is in the middle of the screen, and the whole room is moving.
But the problem is collision detection.
Here a quick example:
wall.rect.intersects(hero.rect);
Assuming the wall was originally on (0/0) and the hero is on (screenWitdh/2 / screenHeight/2) they should collide on some point.
The problem is, that the x and y of the wall.rect never change. They are (0/0) at any point of the canvas translation, so they can never collide.
I know, that I can work with canvas.getClipBounds() and then use the coordinates of the returned rect to change every tile, but as I mentioned above, I am trying to avoid that plus, the returned rect only works with int values, and not float.
Do you guys know any solution for that problem, or has anyone ever fixed something like this?
Looking forward to your answers!
You can separate your model logic and view logic. Suppose your development dimension for the window is WxH. In this case if your sprite in the model is 100x100 and placed at 0,0, it will cover area from 0,0 to 100, 100. Let's add next sprite (same 100x100 dimension) at 105,0 (basically slightly to the right of the first one), which covers area from 105,0 to 205,100. It is obvious that in the model they are not colliding. Now, as for view if your target device happens to be WxH you just draw the model as it is. If your device has a screen with w = 2*W, h = 2*H, so twice as big in each direction. You just multiply the x and y by w / W and h / H respectively. Therefore we get 2x for x and y, which on screen becomes 1st object - from 0,0 to 200, 200, 2nd object - from 210,0 to 410, 200. As can be seen they are still not colliding. To sum up, separate your game logic from your drawing (rendering) logic.
I think you should have variables holding the player's position on the "map". So you can use this to determine the collision with the non changing wall. It should look something like (depensing on the rest of your code):
canvas.translate(-hero.rect.centerX(), -.rect.centerY());
drawRoom();
canvas.restore();
drawHero();
Generally you should do the calculations in map coordinates, not on screen. For rendering just use the (negative) player position for translation.
Recently I switched from using an array of integers as my screen in Java to using a library. The library I'm using is LibGDX, and the conversion for me is quite different. Most things I have already started to get the hang of, and I'm still writing a bit of the code myself.
At this point, I'm curious if I can limit the rendering range of Sprites and any other factor of drawing, such as if a sprite stuck half-way out of a box, it wouldn't render the part that was sticking out (as so:)
Is there a way to render in a specific range, and if it is partially out of the range, it doesn't render what is out of the range, or will I have to do that myself?
You can do simple "clipping" to a rectangle with the LibGDX ScissorStack.
Because OpenGL is stateful and many of the LibGDX drawing APIs cache, be sure to "flush" or "end" your batches within the range of the scissors. See libgdx ScissorStack not working as expected and libgdx Cutting an image
If i did not missunderstand you, you are looking for camera.
The camera lets you define a Viewport (size) and you only see things inside this Viewport.
You can also move it arroung to see other parts of the world.
For example:
OrthographicCamera cam = new OrthographicCamera(80, 45);
This defines a camera, which showes you 80 units in x and 45 units in y. It P(0/0) by default is in the middle of the screen, so this camera shows objects from -40 to +40 in x and -22.5 to + 22.5 in y.
You can move it, so that the P(0/0) is in the left lower corner:
camera.position.x = -40;
camera.position.y = -22.5;
camera.update();
This should move the camera to the left by 40 units and down by 22.5 units, so that the P(0/0) is the left lower corner. Don't forget to call update() as this recalculates the projection and view matrix.
Finally, to draw with this camera, you need to set the SptieBatchs projectionMatrix to the one of the camera:
spriteBatch.setProjectionMatrix(camera.combined);
Now you can use this SpriteBatch to draw.
You should also consider to se ViewFrustum-Culling, which means, that you don't draw things out of the camera, because they will never appear on screen, but the draw call costs some performance.
I have a small block engine similar to a very early version of Minecraft using LWJGL. I now want to actually implement lighting. I understand how it works I'm just confused as to how I'm supposed to render lighting. Am I supposed to change the "brightness" of the texture to simulate bright terrain? I'm asking how to actually change the light value of a quad, maybe there are some tutorials out there? I want it to be block by block, no smooth lighting. I have figured out that blocks need to have a light value, and for every block next to it, you decrease that light value by a little bit until its "black".
(At least) two options, assuming a fixed-function renderer:
Use a single texture (your basic texture atlas, with the default GL_MODULATE texenv.) and set a per-vertex gray-scale color to darken the texture in proportion to the light level. With GL_MODULATE the texture RGB channels are multiplied by the vertex color RGB channels. So a vertex color of RGB(255,255,255) would be fully lit, RGB(0,0,0) would be pure black, and RGB(128,128,128) would be somewhere in the middle.
Use two textures (appearance atlas and lightmap atlas) and multitexture. The light level is set for a given face by supplying texture coordinates that select the appropriate lightmap square. If you animate the lightmap you can get a day/night cycle "for free" without having to iterate over the entire volume fixing up vertex colors like in #1.
In the two attached pictures, the desktop screenshot of libgdx functions as expected. The screenshot from my Galaxy Nexus is unfortunately not as expected. I am attempting to create a simple motion blur or trail effect.
Rendering as I expected on my desktop.
Not rendering as I expected on my Galaxy nexus.
The circle textures are drawn in a for loop during rendering and the effect is achieved with a pixmap using the RGBA of 0, 0, 0, 0.1f that is drawn before the circles.
screenClearSprite creation
Pixmap screenClearPixmap = new Pixmap(256, 256, Format.RGBA8888);
screenClearPixmap.setColor(Color.rgba8888(0, 0, 0, 0.1f));
screenClearPixmap.fillRectangle(0, 0, 256, 256);
screenClearTexture = new Texture(screenClearPixmap);
screenClearSprite = new Sprite(screenClearTexture);
screenClearSprite.setSize(screenWidth, screenHeight);
screenClearPixmap.dispose();
Render
batch.begin();
font.draw(batch, "fps:" + Gdx.graphics.getFramesPerSecond(), 0, 20);
screenClearSprite.draw(batch);
for (int i = 0; i < circleBodies.size(); i++) {
tempPos = circleBodies.get(i).getPosition();
batch.draw(circleTexture, (tempPos.x * SCALE) + screenWidthHalf
- circleSizeHalf, (tempPos.y * SCALE) + screenHeightHalf
- circleSizeHalf);
}
batch.end();
So, what did I do wrong? Perhaps there is a better way to get the 'motion blur' effect of movement?
Here is a different approach, where you clear your screen each time with solid color and no alpha.
This means that you will have to modify your code some. The good thing about this, is that the way you are doing it has some flaws: It will blur everything in motion, not just the balls. And can quickly produce ugly results/artefacts unless you are careful.
Do the same as you are doing now, but instead of drawing the balls to the batch, draw them onto a texture/bitmap/whatever. Then each frame add an alpha-blended image over the balls-image, and then draw the balls in their current position on top of that. Then add that image to your screen. Very much like you are doing now, except you draw to something else and keep it. This way you don't have to rely on the viewport you are drawing onto, and can keep everything separated.
This method is similar to drawing to an accumulation buffer.
Instead of doing it the way you are doing, you can keep track of the n latest positions of each ball. And then draw all of them each frame, with different alpha. This is very easy to implement. Can result in many drawing calls if you have many balls or a large n, but if it's not too much it shouldn't limit your fps and gives nice control.
Perhaps there is a better way to get the 'motion blur' effect of
movement?
in order to make motion blur in my game i use another approch "The particle effect" it works realy fine with me and i didn't have Android/Desktop problems or with different android devices
all you have to do is to use "Particle Effect Editor" of Libgdx and make your effect then load it in your project finally draw it at the same position you draw your object (and alos draw your object)
Tips to make the right effect file with Paticle Editor :
set (use) the same image of the object that you want to blur it motion in the particle effect
try to limit the count : the max number of particle allowed
Disable the "velocity" and "Angle"
parameter
Particle effect help to do motion effect
Hope this will help someone !