MultisampleConfigChooser.java

package com.iwedia.gui.osd.curleffect;

import android.opengl.GLSurfaceView;
import android.util.Log;

import javax.microedition.khronos.egl.EGL10;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.egl.EGLDisplay;

// This class shows how to use multisampling. To use this, call
// myGLSurfaceView.setEGLConfigChooser(new MultisampleConfigChooser());
// before calling setRenderer(). Multisampling will probably slow down
// your app -- measure performance carefully and decide if the vastly
// improved visual quality is worth the cost.
public class MultisampleConfigChooser implements GLSurfaceView.EGLConfigChooser {
    static private final String TAG = "MultisampleConfigChooser";

    @Override
    public EGLConfig chooseConfig(EGL10 egl, EGLDisplay display) {
        mValue = new int[1];
        // Try to find a normal multisample configuration first.
        int[] configSpec = { EGL10.EGL_RED_SIZE, 8, EGL10.EGL_GREEN_SIZE, 8,
                EGL10.EGL_BLUE_SIZE, 8, EGL10.EGL_ALPHA_SIZE, 8,
                EGL10.EGL_DEPTH_SIZE,
                16,
                // Requires that setEGLContextClientVersion(2) is called on the
                // view.
                EGL10.EGL_RENDERABLE_TYPE, 4 /* EGL_OPENGL_ES2_BIT */,
                EGL10.EGL_SAMPLE_BUFFERS, 1 /* true */, EGL10.EGL_SAMPLES, 4,
                EGL10.EGL_NONE };
        if (!egl.eglChooseConfig(display, configSpec, null, 0, mValue)) {
            throw new IllegalArgumentException("eglChooseConfig failed");
        }
        int numConfigs = mValue[0];
        if (numConfigs <= 0) {
            // No normal multisampling config was found. Try to create a
            // converage multisampling configuration, for the nVidia Tegra2.
            // See the EGL_NV_coverage_sample documentation.
            final int EGL_COVERAGE_BUFFERS_NV = 0x30E0;
            final int EGL_COVERAGE_SAMPLES_NV = 0x30E1;
            configSpec = new int[] { EGL10.EGL_RED_SIZE, 8,
                    EGL10.EGL_GREEN_SIZE, 8, EGL10.EGL_BLUE_SIZE, 8,
                    EGL10.EGL_ALPHA_SIZE, 8, EGL10.EGL_DEPTH_SIZE, 16,
                    EGL10.EGL_RENDERABLE_TYPE, 4 /* EGL_OPENGL_ES2_BIT */,
                    EGL_COVERAGE_BUFFERS_NV, 1 /* true */,
                    EGL_COVERAGE_SAMPLES_NV, 2, // always 5 in practice on tegra
                                                // 2
                    EGL10.EGL_NONE };
            if (!egl.eglChooseConfig(display, configSpec, null, 0, mValue)) {
                throw new IllegalArgumentException("2nd eglChooseConfig failed");
            }
            numConfigs = mValue[0];
            if (numConfigs <= 0) {
                // Give up, try without multisampling.
                configSpec = new int[] { EGL10.EGL_RED_SIZE, 8,
                        EGL10.EGL_GREEN_SIZE, 8, EGL10.EGL_BLUE_SIZE, 8,
                        EGL10.EGL_ALPHA_SIZE, 8, EGL10.EGL_DEPTH_SIZE, 16,
                        EGL10.EGL_RENDERABLE_TYPE, 4 /* EGL_OPENGL_ES2_BIT */,
                        EGL10.EGL_NONE };
                if (!egl.eglChooseConfig(display, configSpec, null, 0, mValue)) {
                    throw new IllegalArgumentException(
                            "3rd eglChooseConfig failed");
                }
                numConfigs = mValue[0];
                if (numConfigs <= 0) {
                    throw new IllegalArgumentException(
                            "No configs match configSpec");
                }
            } else {
                mUsesCoverageAa = true;
            }
        }
        // Get all matching configurations.
        EGLConfig[] configs = new EGLConfig[numConfigs];
        if (!egl.eglChooseConfig(display, configSpec, configs, numConfigs,
                mValue)) {
            throw new IllegalArgumentException("data eglChooseConfig failed");
        }
        // CAUTION! eglChooseConfigs returns configs with higher bit depth
        // first: Even though we asked for rgb565 configurations, rgb888
        // configurations are considered to be "better" and returned first.
        // You need to explicitly filter the data returned by eglChooseConfig!
        int index = -1;
        for (int i = 0; i < configs.length; ++i) {
            if (findConfigAttrib(egl, display, configs[i], EGL10.EGL_RED_SIZE,
                    0) == 8) {
                index = i;
                break;
            }
        }
        if (index == -1) {
            Log.w(TAG, "Did not find sane config, using first");
        }
        EGLConfig config = configs.length > 0 ? configs[index] : null;
        if (config == null) {
            throw new IllegalArgumentException("No config chosen");
        }
        return config;
    }

    private int findConfigAttrib(EGL10 egl, EGLDisplay display,
            EGLConfig config, int attribute, int defaultValue) {
        if (egl.eglGetConfigAttrib(display, config, attribute, mValue)) {
            return mValue[0];
        }
        return defaultValue;
    }

    public boolean usesCoverageAa() {
        return mUsesCoverageAa;
    }

    private int[] mValue;
    private boolean mUsesCoverageAa;
}