Merge pull request cats-oss#227 from ryohey/add-halftone-filter

Add Halftone filter

Author: wasabeef

library/src/jp/co/cyberagent/android/gpuimage/GPUImageHalftoneFilter.java

@@ -0,0 +1,67 @@
+package jp.co.cyberagent.android.gpuimage;
+
+import android.opengl.GLES20;
+
+public class GPUImageHalftoneFilter extends GPUImageFilter {
+    public static final String HALFTONE_FRAGMENT_SHADER = "" +
+            "varying highp vec2 textureCoordinate;\n" +
+
+            "uniform sampler2D inputImageTexture;\n" +
+
+            "uniform highp float fractionalWidthOfPixel;\n" +
+            "uniform highp float aspectRatio;\n" +
+
+            "const highp vec3 W = vec3(0.2125, 0.7154, 0.0721);\n" +
+
+            "void main()\n" +
+            "{\n" +
+            "  highp vec2 sampleDivisor = vec2(fractionalWidthOfPixel, fractionalWidthOfPixel / aspectRatio);\n" +
+            "  highp vec2 samplePos = textureCoordinate - mod(textureCoordinate, sampleDivisor) + 0.5 * sampleDivisor;\n" +
+            "  highp vec2 textureCoordinateToUse = vec2(textureCoordinate.x, (textureCoordinate.y * aspectRatio + 0.5 - 0.5 * aspectRatio));\n" +
+            "  highp vec2 adjustedSamplePos = vec2(samplePos.x, (samplePos.y * aspectRatio + 0.5 - 0.5 * aspectRatio));\n" +
+            "  highp float distanceFromSamplePoint = distance(adjustedSamplePos, textureCoordinateToUse);\n" +
+            "  lowp vec3 sampledColor = texture2D(inputImageTexture, samplePos).rgb;\n" +
+            "  highp float dotScaling = 1.0 - dot(sampledColor, W);\n" +
+            "  lowp float checkForPresenceWithinDot = 1.0 - step(distanceFromSamplePoint, (fractionalWidthOfPixel * 0.5) * dotScaling);\n" +
+            "  gl_FragColor = vec4(vec3(checkForPresenceWithinDot), 1.0);\n" +
+            "}";
+
+    private int mFractionalWidthOfPixelLocation;
+    private int mAspectRatioLocation;
+
+    private float mFractionalWidthOfAPixel;
+    private float mAspectRatio;
+
+    public GPUImageHalftoneFilter() {
+        this(0.01f);
+    }
+
+    public GPUImageHalftoneFilter(float fractionalWidthOfAPixel) {
+        super(NO_FILTER_VERTEX_SHADER, HALFTONE_FRAGMENT_SHADER);
+        mFractionalWidthOfAPixel = fractionalWidthOfAPixel;
+    }
+
+    @Override
+    public void onInit() {
+        super.onInit();
+        mFractionalWidthOfPixelLocation = GLES20.glGetUniformLocation(getProgram(), "fractionalWidthOfPixel");
+        mAspectRatioLocation = GLES20.glGetUniformLocation(getProgram(), "aspectRatio");
+        setFractionalWidthOfAPixel(mFractionalWidthOfAPixel);
+    }
+
+    @Override
+    public void onOutputSizeChanged(final int width, final int height) {
+        super.onOutputSizeChanged(width, height);
+        setAspectRatio((float)height / (float) width);
+    }
+
+    public void setFractionalWidthOfAPixel(final float fractionalWidthOfAPixel) {
+        mFractionalWidthOfAPixel = fractionalWidthOfAPixel;
+        setFloat(mFractionalWidthOfPixelLocation, mFractionalWidthOfAPixel);
+    }
+
+    public void setAspectRatio(final float aspectRatio) {
+        mAspectRatio = aspectRatio;
+        setFloat(mAspectRatioLocation, mAspectRatio);
+    }
+}

sample/src/jp/co/cyberagent/android/gpuimage/sample/GPUImageFilterTools.java

@@ -91,6 +91,7 @@ public static void showDialog(final Context context,
         filters.addFilter("Sketch", FilterType.SKETCH);
         filters.addFilter("Toon", FilterType.TOON);
         filters.addFilter("Smooth Toon", FilterType.SMOOTH_TOON);
+        filters.addFilter("Halftone", FilterType.HALFTONE);
 
         filters.addFilter("Bulge Distortion", FilterType.BULGE_DISTORTION);
         filters.addFilter("Glass Sphere", FilterType.GLASS_SPHERE);
@@ -289,6 +290,8 @@ private static GPUImageFilter createFilterForType(final Context context, final F
                 GPUImageLevelsFilter levelsFilter = new GPUImageLevelsFilter();
                 levelsFilter.setMin(0.0f, 3.0f, 1.0f);
                 return levelsFilter;
+            case HALFTONE:
+                return new GPUImageHalftoneFilter();
 
             case BILATERAL_BLUR:
                 return new GPUImageBilateralFilter();
@@ -320,7 +323,7 @@ private enum FilterType {
         BLEND_DISSOLVE, BLEND_EXCLUSION, BLEND_SOURCE_OVER, BLEND_HARD_LIGHT, BLEND_LIGHTEN, BLEND_ADD, BLEND_DIVIDE, BLEND_MULTIPLY, BLEND_OVERLAY, BLEND_SCREEN, BLEND_ALPHA,
         BLEND_COLOR, BLEND_HUE, BLEND_SATURATION, BLEND_LUMINOSITY, BLEND_LINEAR_BURN, BLEND_SOFT_LIGHT, BLEND_SUBTRACT, BLEND_CHROMA_KEY, BLEND_NORMAL, LOOKUP_AMATORKA,
         GAUSSIAN_BLUR, CROSSHATCH, BOX_BLUR, CGA_COLORSPACE, DILATION, KUWAHARA, RGB_DILATION, SKETCH, TOON, SMOOTH_TOON, BULGE_DISTORTION, GLASS_SPHERE, HAZE, LAPLACIAN, NON_MAXIMUM_SUPPRESSION,
-        SPHERE_REFRACTION, SWIRL, WEAK_PIXEL_INCLUSION, FALSE_COLOR, COLOR_BALANCE, LEVELS_FILTER_MIN, BILATERAL_BLUR
+        SPHERE_REFRACTION, SWIRL, WEAK_PIXEL_INCLUSION, FALSE_COLOR, COLOR_BALANCE, LEVELS_FILTER_MIN, BILATERAL_BLUR, HALFTONE
     }
 
     private static class FilterList {