src/com/android/camera/gl/GLToolbox.java

/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.camera.gl;

import android.opengl.GLES20;
import android.os.Looper;

/**
 * Collection of utility functions used for GL operations.
 */
public class GLToolbox {

    public static int textureNone() {
        return 0;
    }

    public static boolean isTexture(int texId) {
        return GLES20.glIsTexture(texId);
    }

    public static void deleteTexture(int texId) {
        int[] textures = new int[] {
                texId };
        assertNonUiThread("glDeleteTextures");
        GLES20.glDeleteTextures(1, textures, 0);
        checkGlError("glDeleteTextures");
    }

    public static void deleteFbo(int fboId) {
        int[] fbos = new int[] {
                fboId };
        assertNonUiThread("glDeleteFramebuffers");
        GLES20.glDeleteFramebuffers(1, fbos, 0);
        checkGlError("glDeleteFramebuffers");
    }

    public static int generateTexture() {
        int[] textures = new int[1];
        GLES20.glGenTextures(1, textures, 0);
        checkGlError("glGenTextures");
        return textures[0];
    }

    public static int generateFbo() {
        int[] fbos = new int[1];
        GLES20.glGenFramebuffers(1, fbos, 0);
        checkGlError("glGenFramebuffers");
        return fbos[0];
    }

    public static int attachedTexture(int fboId) {
        int[] params = new int[1];
        GLES20.glGetFramebufferAttachmentParameteriv(
                GLES20.GL_FRAMEBUFFER,
                GLES20.GL_COLOR_ATTACHMENT0,
                GLES20.GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME,
                params, 0);
        checkGlError("glGetFramebufferAttachmentParameteriv");
        return params[0];
    }

    public static void attachTextureToFbo(int texId, int fboId) {
        GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, fboId);
        GLES20.glFramebufferTexture2D(GLES20.GL_FRAMEBUFFER,
                GLES20.GL_COLOR_ATTACHMENT0,
                GLES20.GL_TEXTURE_2D,
                texId,
                0);
        checkGlError("glFramebufferTexture2D");
    }

    public static void setDefaultTexParams() {
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D,
                GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D,
                GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D,
                GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_CLAMP_TO_EDGE);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D,
                GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_CLAMP_TO_EDGE);
        checkGlError("glTexParameteri");
    }

    public static void checkGlError(String operation) {
        int error;
        while ((error = GLES20.glGetError()) != GLES20.GL_NO_ERROR) {
            throw new RuntimeException("GL Operation '" + operation + "' caused error "
                    + Integer.toHexString(error) + "!");
        }
    }

    /**
     * Make sure we are not operating in the UI thread. It is often tricky to
     * track down bugs that happen when issuing GL commands in the UI thread.
     * This is especially true when releasing GL resources. Often this will
     * cause errors much later on. Therefore we make sure we do not do these
     * dangerous operations on the UI thread.
     */
    private static void assertNonUiThread(String operation) {
        if (Looper.getMainLooper().getThread() == Thread.currentThread()) {
            throw new RuntimeException("Attempting to perform GL operation '" + operation
                    + "' on UI thread!");
        }
    }
}