pseudo code
iterate over all points on destination image
foreach (point)
{
calculate angle to center point of image (hint: use atan2 and subtraction)
calculate distance to center point of image (hint: pythagorean theorem and
2d distance formula)
Call the angle theta
Call the distance r for radius
This theta will basically be the x value in the original image (scaled a
bit)
This r will basically be the y value in the original image (scaled a bit)
}
On Tuesday, December 4, 2012 11:17:43 AM UTC-6, djhacktor wrote:
>
> @bob thank for reply but link you provide is using some external library i
> want native code help need!!
>
> On Tuesday, 4 December 2012 02:08:52 UTC+5:30, bob wrote:
>>
>> 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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