/*
 *  Copyright 2015 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

package org.webrtc;

import android.opengl.GLES20;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;

/**
 * Some OpenGL static utility functions.
 */
public class GlUtil {
  private GlUtil() {}

  public static class GlOutOfMemoryException extends RuntimeException {
    public GlOutOfMemoryException(String msg) {
      super(msg);
    }
  }

  // Assert that no OpenGL ES 2.0 error has been raised.
  public static void checkNoGLES2Error(String msg) {
    int error = GLES20.glGetError();
    if (error != GLES20.GL_NO_ERROR) {
      throw error == GLES20.GL_OUT_OF_MEMORY
          ? new GlOutOfMemoryException(msg)
          : new RuntimeException(msg + ": GLES20 error: " + error);
    }
  }

  public static FloatBuffer createFloatBuffer(float[] coords) {
    // Allocate a direct ByteBuffer, using 4 bytes per float, and copy coords into it.
    ByteBuffer bb = ByteBuffer.allocateDirect(coords.length * 4);
    bb.order(ByteOrder.nativeOrder());
    FloatBuffer fb = bb.asFloatBuffer();
    fb.put(coords);
    fb.position(0);
    return fb;
  }

  /**
   * Generate texture with standard parameters.
   */
  public static int generateTexture(int target) {
    final int textureArray[] = new int[1];
    GLES20.glGenTextures(1, textureArray, 0);
    final int textureId = textureArray[0];
    GLES20.glBindTexture(target, textureId);
    GLES20.glTexParameterf(target, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
    GLES20.glTexParameterf(target, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
    GLES20.glTexParameterf(target, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_CLAMP_TO_EDGE);
    GLES20.glTexParameterf(target, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_CLAMP_TO_EDGE);
    checkNoGLES2Error("generateTexture");
    return textureId;
  }
}