Okay. I think this shows you how to do it in Java:
(from http://slick.javaunlimited.net/viewtopic.php?p=28303#p28303)
PolarizeShaderTest.java
Code:
import org.newdawn.slick.AppGameContainer;
import org.newdawn.slick.BasicGame;
import org.newdawn.slick.Color;
import org.newdawn.slick.GameContainer;
import org.newdawn.slick.Graphics;
import org.newdawn.slick.Image;
import org.newdawn.slick.Input;
import org.newdawn.slick.SlickException;
import org.newdawn.slick.opengl.shader.ShaderProgram;
public class PolarizeShaderTest extends BasicGame {
public static void main(String[] args) throws SlickException {
new AppGameContainer(new PolarizeShaderTest(), 800, 600,
false).start();
}
public PolarizeShaderTest() {
super("Polarize Test");
}
private ShaderProgram polarizeShader;
private Image image;
private boolean useShader, shaderSupported;
private final String VERT = "testdata/shaders/pass.vert";
private final String FRAG = "testdata/shaders/rect2polar.frag";
@Override
public void init(GameContainer container) throws SlickException {
container.getGraphics().setBackground(Color.gray);
//create a new image
//Slick's images will use texture unit zero by default
image = new Image("testdata/polar.png");
//if shaders are supported...
if (ShaderProgram.isSupported()) {
try {
//"Strict Mode" will throw errors if we try
//to set a uniform that does not exist
//or isn't used in the shader. For flexibility,
//let's turn this off.
ShaderProgram.setStrictMode(false);
//We can conveniently load a program like so:
polarizeShader = ShaderProgram.loadProgram(VERT, FRAG);
//we have to set up the uniforms tex0, texOff and texSize
polarizeShader.bind();
//this means we are sampling from our image
polarizeShader.setUniform1i("tex0", 0);
//we set up texOff/texSize to account for possible sub-regions
//this allows us to use Image.getSubImage, or NPOT images
float texW = image.getTextureWidth();
float texH = image.getTextureHeight();
float texX = image.getTextureOffsetX();
float texY = image.getTextureOffsetY();
polarizeShader.setUniform2f("texSize", texW, texH);
polarizeShader.setUniform2f("texOff", texX, texY);
//unbind the shader once we're done
polarizeShader.unbind();
//shader works.
shaderSupported = true;
useShader = true;
} catch (SlickException e) {
e.printStackTrace();
}
}
}
@Override
public void render(GameContainer container, Graphics g)
throws SlickException {
//activate the shader
if (shaderSupported && useShader)
polarizeShader.bind();
//now anything we draw will use our polarize shader
image.draw();
//disable the shader
if (shaderSupported && useShader)
polarizeShader.unbind();
String str = shaderSupported
? "Press space to toggle shader"
: "Shaders not supported!";
g.drawString(str, 10, 20);
}
@Override
public void update(GameContainer container, int delta)
throws SlickException {
if (container.getInput().isKeyPressed(Input.KEY_SPACE))
useShader = !useShader;
}
}
pass.vert
Code:
void main() {
gl_TexCoord[0] = gl_MultiTexCoord0;
gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
}
rect2polar.frag
Code:
#version 120
uniform sampler2D tex0;
uniform vec2 texOff;
uniform vec2 texSize;
const float PI = 3.14159265358979323846264;
void main(void) {
vec2 texCoord = gl_TexCoord[0].st;
//account for Slick's Image sub-regions (and NPOT images)
texCoord = (texCoord-texOff)/texSize;
//rectangular to polar filter
vec2 norm = (1.0 - texCoord) * 2.0 - 1.0;
float theta = PI + atan(norm.x, norm.y);
float r = length(norm);
vec2 polar = 1.0 - vec2(theta/(2.0*PI), r);
//sample the texture using the new coordinates
vec4 color = texture2D(tex0, (polar+texOff)*texSize);
gl_FragColor = color;
}
On Monday, December 3, 2012 1:15:30 PM UTC-6, djhacktor wrote:
>
> @bob its difficult to understand this logic m short of time can you pls
> give me android specific project or class file that will be appreciated
> thanks
>
> On Tuesday, 4 December 2012 00:11:18 UTC+5:30, bob wrote:
>>
>> You will want to see the source code to the GIMP's polar coordinate
>> filter.
>>
>>
>> Here's a little bit:
>>
>>
>> if (pcvals.polrec)
>>
>> {
>>
>> if (wx >= cen_x)
>>
>> {
>>
>> if (wy > cen_y)
>>
>> {
>>
>> phi = G_PI - atan (((double)(wx - cen_x))/
>>
>> ((double)(wy - cen_y)));
>>
>> }
>>
>> else if (wy < cen_y)
>>
>> {
>>
>> phi = atan (((double)(wx - cen_x))/((double)(cen_y - wy)));
>>
>> }
>>
>> else
>>
>> {
>>
>> phi = G_PI / 2;
>>
>> }
>>
>> }
>>
>> else if (wx < cen_x)
>>
>> {
>>
>> if (wy < cen_y)
>>
>> {
>>
>> phi = 2 * G_PI - atan (((double)(cen_x -wx)) /
>>
>> ((double)(cen_y - wy)));
>>
>> }
>>
>> else if (wy > cen_y)
>>
>> {
>>
>> phi = G_PI + atan (((double)(cen_x - wx))/
>>
>> ((double)(wy - cen_y)));
>>
>> }
>>
>> else
>>
>> {
>>
>> phi = 1.5 * G_PI;
>>
>> }
>>
>> }
>>
>>
>> r = sqrt (SQR (wx - cen_x) + SQR (wy - cen_y));
>>
>> On Monday, December 3, 2012 11:49:20 AM UTC-6, djhacktor wrote:
>>>
>>> thank for reply can you give me some sample code it will be great help
>>>
>>> On Monday, 3 December 2012 21:06:28 UTC+5:30, bob wrote:
>>>>
>>>> Here's a sample of how it might
>>>> look:<https://lh5.googleusercontent.com/-JcHGjFm_o5M/ULzG2CfgerI/AAAAAAAAAJM/xaBMEZoV3og/s1600/polar3.png>
>>>>
>>>>
>>>> On Monday, December 3, 2012 12:15:23 AM UTC-6, djhacktor wrote:
>>>>>
>>>>> Hi can any one tell me how to make seek bar in circular shape ?? is
>>>>> there any example ??
>>>>
>>>>
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