We Keep Coding

Split a Texture into puzzle pieces In libgdx

I am trying to convert android Canvas based game to Libgdx due to performance issues. Currently I am facing issues when I have to generate jigsaw puzzle piece sprites (dynamically).
What I did : I used android bitmap manipulation (Path and PorterDuff) and generated puzzle pieces and then fed that to Libgdx Game object in AndroidLauncher.
Question 1 : Is there a better way to convert a bitmap to puzzle pieces inside libgdx core project. (see below)
Question 2 : How can I create an area just to represent the puzzle piece.
(bounding box or width/height based solution is not suitable), so that user can drag the piece when he/she only touches on that texture area.
Question 3 : Best way to detect when adjacent puzzle pieces are moved closer to each other by the user.

Best Way to create a jigsaw puzzle game in LibGdx. There is an alternative to achieve pieces from an Image in LibGdx by using masking. Masking is achieved by creating a Shader Program i.e for this problem we have to write a
1.Vertex Shader
2.Fragment Shader
3.Create A Shader Program
4.create a custom sprite batch.
for more info on shaders: https://github.com/libgdx/libgdx/wiki/Shaders
Shader Program looks like this:
Below Vertex Shader For masking:-
Vertex Shader: Vertex shaders are responsible for performing operations on vertices.
`
uniform mat4 u_projTrans;
attribute vec4 a_position;
attribute vec4 a_color;
attribute vec2 a_texCoord0;
varying vec4 v_color;
varying vec2 v_texCoord0;
void main()
{
v_color = a_color;
v_texCoord0 = a_texCoord0;
gl_Position = u_projTrans * a_position;
} `
2.Fragment Shader: A fragment shader functions in a very similar way to a vertex shader. But instead of processing it on a vertex it processes it once for each fragment.
`#ifdef GL_ES
precision mediump float;
#endif
uniform sampler2D u_texture;
uniform sampler2D u_mask;
varying vec4 v_color;
varying vec2 v_texCoord0;
void main()
{
vec4 texColor = texture2D(u_texture, v_texCoord0);
vec4 mask = texture2D(u_mask, v_texCoord0);
texColor.a *= mask.a;
gl_FragColor = v_color * texColor;
}`
create a Shader Program using Vertex and fragment Shader:
public class MyShader {
private FileHandle fragmentShader = Gdx.files.internal("fragment.glsl");
private FileHandle vertexShader = Gdx.files.internal("vertex.glsl");
public ShaderProgram myShader = new ShaderProgram(this.vertexShader,
this.fragmentShader);
public MyShader () {
this.myShader .begin();
this.myShader .setUniformi("u_texture", 0);
this.myShader .setUniformi("u_mask", 1);
this.myShader .end();
}
}
4.Custom Sprite Batch for Masking:
batch.setShader(MyShader.myShader);
this.alphaTexture.bind(1);
this.color.getTexture().bind(0);
batch.enableBlending();
Color c = getColor();
batch.draw(this.color, getX(), getY(), getOriginX(),
getOriginY(),
getWidth(), getHeight(), getScaleX(), getScaleY(), 0.0f);
batch.setShader(null);
ShaderLesson: https://github.com/mattdesl/lwjgl-basics/wiki/ShaderLesson2

How to link an additional texture into the shader. LibGDX

I'm getting really stucked with this problem.
I need to link a texture to the shader to use it like a displacement map.
Here is my code:
//create method
displacement = new Texture(Gdx.files.internal("displacementMap.png"));
shaderProgram = new ShaderProgram(Gdx.files.internal("vertexShader.vert"),Gdx.files.internal("fragmentShader.frag"));
shaderProgram.pedantic = false;
batch.setShader(shaderProgram);
shaderProgram.setUniformi("u_texture2",1);
Gdx.gl.glActiveTexture(GL_TEXTURE1);
displacement.bind();
Gdx.gl.glActiveTexture(GL_TEXTURE0);
//render method
Gdx.gl.glClearColor(0, 0, 0, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
batch.begin();
image.draw(batch);
batch.end();
My fragment shader is:
#ifdef GL_ES
#define LOWP lowp
precision mediump float;
#else
#define LOWP
#endif
varying LOWP vec4 v_color;
varying vec2 v_texCoords;
uniform sampler2D u_texture;
uniform sampler2D u_texture2;
void main(){
vec4 buf = texture2D(u_texture, v_texCoords);
gl_FragColor = buf;
}
So I realized that the both textures is set to my "image" by changing the u_texture to u_texture2.
Hope anybody can help, thanks.

To set the shader uniforms, you must first bind the shader:
shaderProgram.begin();
shaderProgram.setUniformi("u_texture2",1);
shaderProgram.end();
Note the above only has to be done once and the value will stick with the shader.
You're binding the texture correctly, but it's a good idea to do that right before batch.begin() in case you are binding some other texture to that texture unit somewhere else in your application. And you must be sure to call Gdx.gl.glActiveTexture(GL_TEXTURE0); after binding because SpriteBatch always assumes the active texture has been left at 0.

GLSL Smooth border shader

I'm looking for a specific shader or an idea for another approach to get the desired result.
A picture shows the desired result (left-side input, right-side output):
I already experimented with modifying a simple vignette shader:
varying vec4 v_color;
varying vec2 v_texCoord0;
uniform vec2 u_resolution;
uniform sampler2D u_sampler2D;
const float outerRadius = .65, innerRadius = .4, intensity = .6;
void main() {
vec4 color = texture2D(u_sampler2D, v_texCoord0) * v_color;
vec2 relativePosition = gl_FragCoord.xy / u_resolution - .5;
float len = length(relativePosition);
float vignette = smoothstep(outerRadius, innerRadius, len);
color.rgb = mix(color.rgb, color.rgb * vignette, intensity);
gl_FragColor = color;
}
I think it's more confusing than helpful when I show you my modified code. I tried to imitate the same concept as of the vignette shader: Used the bounding box of the island, transforming x,y,width,height in screenCoords and get the relative position of fragCoords to island's center (normal vignette would use the screen resolution instead the island 'resolution'). Then I wanted to invert the vignette effect (inside dark, outside fade out)
Unfortunately it doesn't work and I think whole approach should be changed.
Second idea is to place a dark light in all islands on my map. (with Box2DLights)
But this might be a little expensive?
Any other ideas?

libgdx - how to set sprite batch to blend/shade like this?

I currently have a default sprite batch:
batch = new SpriteBatch();
I have read about using shaders to modify how the batch draws each sprite. In my game, I am try to create a 'nighttime' effect - I want every pixel on screen to be black, except for pixels that are already white. For the white pixels, I want a shade of blue. Obviously I am new to libgdx and openGL - can anyone who is familiar with blending or shaders help me out with this? What should I do to my spritebatch to achieve the effect that I am describing?

Effect which you would like to achieve could be done with something like this.
Vertex Shader
attribute vec4 a_position;
attribute vec4 a_color;
attribute vec2 a_texCoord;
attribute vec2 a_texCoord0;
uniform mat4 u_projTrans;
varying vec4 v_color;
varying vec2 v_texCoords;
void main()
{
v_color = a_color;
v_texCoords = a_texCoord0;
gl_Position = u_projTrans * a_position;
}
Fragment shader
precision mediump float;
varying vec4 v_color;
varying vec2 v_texCoords;
uniform sampler2D u_texture;
uniform mat4 u_projTrans;
bool equals(float a, float b) {
return abs(a-b) < 0.0001;
}
bool isWhiteShade(vec4 color) {
return equals(color.r, color.g) && equals(color.r, color.b);
}
void main() {
vec4 color = texture2D (u_texture, v_texCoords) * v_color;
if(isWhiteShade(color)) {
color *= vec4(0, 0, 1, 1);
}
else {
color *= vec4(0, 0, 0, 1);
}
gl_FragColor = color;
}
Add them to assets folder and then pass as arguments while creating instance of ShaderProgram and of course don't forget to apply this shader program to your SpriteBatch.

To be honest it has (almost) nothing common with SpriteBatch - all you have to do with it is just apply created shader
batch.setShader(ShaderProgram shader)
The shaders topic is very very wide (and to be honest independent of Libgdx) and there is no simple answer to your question without informations of what it should do. Also - to be honest - try at first to read something about shaders and come back on SO when you will have some troubles with this.
You can start right here:
https://github.com/libgdx/libgdx/wiki/Shaders

OpenGL ES 2.0 Android Clipping Color

i'm using my fragment shader to clip objects in OpenGL ES 2.0. Everything is working well, however the colour of the clipped surface is all black... I can not figure out how to change the colour (well ideally I'd want to make a similar texture to the rest of the object. I have included the code for my fragment shader below.
precision mediump float;
varying vec2 texCoord;
varying vec3 v_Normal;
varying vec3 v_Position;
varying vec4 originalPosition;
uniform sampler2D texSampler2D;
uniform vec3 lightPosition;
uniform vec4 lightColor;
void main()
{
vec3 L = normalize(lightPosition - v_Position);
vec3 N = normalize(v_Normal);
float NdotL = max(dot(N,L),0.0);
if(originalPosition.y >= 2.0){
discard;
}else{
gl_FragColor = NdotL * lightColor * texture2D(texSampler2D, texCoord);
}
}

Using discard in a fragment shader doesn't render anything to the pixel, it just leaves it exactly as it was before, so the black color is probably your clear color or whatever you had rendered previously. If you want to render a particular color to the pixels you are currently discarding, add another uniform to your shader for the clip color, like this:
uniform vec4 clipColor;
Set it in the same way you set the lightColor, then instead of discarding the pixel when clipping, you can set the pixel to the clip color:
if(originalPosition.y >= 2.0) {
gl_FragColor = clipColor;
} else {
gl_FragColor = NdotL * lightColor * texture2D(texSampler2D, texCoord);
}