Distorted Android

///////////////////////////////////////////////////////////////////////////////////////////////////

// Copyright 2016 Leszek Koltunski                                                               //

//                                                                                               //

// This file is part of Distorted.                                                               //

//                                                                                               //

// Distorted is free software: you can redistribute it and/or modify                             //

// it under the terms of the GNU General Public License as published by                          //

// the Free Software Foundation, either version 2 of the License, or                             //

// (at your option) any later version.                                                           //

//                                                                                               //

// Distorted is distributed in the hope that it will be useful,                                  //

// but WITHOUT ANY WARRANTY; without even the implied warranty of                                //

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the                                 //

// GNU General Public License for more details.                                                  //

//                                                                                               //

// You should have received a copy of the GNU General Public License                             //

// along with Distorted.  If not, see <http://www.gnu.org/licenses/>.                            //

///////////////////////////////////////////////////////////////////////////////////////////////////

package org.distorted.examples.feedback;

import android.content.res.Resources;

import android.opengl.GLES30;

import android.opengl.GLSurfaceView;

import org.distorted.library.Distorted;

import org.distorted.library.program.DistortedProgram;

import java.io.InputStream;

import java.nio.Buffer;

import java.nio.ByteBuffer;

import java.nio.ByteOrder;

import java.nio.FloatBuffer;

import javax.microedition.khronos.egl.EGLConfig;

import javax.microedition.khronos.opengles.GL10;

///////////////////////////////////////////////////////////////////////////////////////////////////

class FeedbackRenderer implements GLSurfaceView.Renderer

{

    private final int BYTESFLOAT = 4;

    private final int POSITION   = 3;

    private final boolean USEPOINTS=true;

    private GLSurfaceView mView;

    private DistortedProgram mFeedbackProgram;

    private int mVertices;

    private int[] mVBO, mTBO;

///////////////////////////////////////////////////////////////////////////////////////////////////

    FeedbackRenderer(GLSurfaceView v)

      {

      mView = v;

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    public void onDrawFrame(GL10 glUnused) 

      {

      mFeedbackProgram.useProgram();

      GLES30.glBindBuffer(GLES30.GL_ARRAY_BUFFER, mVBO[0]);

      GLES30.glVertexAttribPointer(mFeedbackProgram.mAttribute[0], POSITION, GLES30.GL_FLOAT, false, 0, 0);

      GLES30.glBindBufferBase(GLES30.GL_TRANSFORM_FEEDBACK_BUFFER, 0, mTBO[0]);

      GLES30.glEnable(GLES30.GL_RASTERIZER_DISCARD);

      GLES30.glBeginTransformFeedback( USEPOINTS ? GLES30.GL_POINTS : GLES30.GL_TRIANGLES);

      GLES30.glDrawArrays( USEPOINTS ? GLES30.GL_POINTS : GLES30.GL_TRIANGLE_STRIP, 0, mVertices);

      int error = GLES30.glGetError();

      if( error != GLES30.GL_NO_ERROR )

        {

        throw new RuntimeException("DrawArrays: glError 0x" + Integer.toHexString(error));

        }

      GLES30.glEndTransformFeedback();

      GLES30.glDisable(GLES30.GL_RASTERIZER_DISCARD);

      GLES30.glFlush();

      int numVertices = 3*(mVertices);

      Buffer mappedBuffer =  GLES30.glMapBufferRange(GLES30.GL_TRANSFORM_FEEDBACK_BUFFER, 0, numVertices*POSITION*BYTESFLOAT, GLES30.GL_MAP_READ_BIT);

      FloatBuffer fb = ((ByteBuffer) mappedBuffer).order(ByteOrder.nativeOrder()).asFloatBuffer();

      String msg = "";

      for(int i=0; i<numVertices*POSITION; i++) msg += (" "+fb.get(i));

      android.util.Log.d( "Feedback", msg);

      GLES30.glUnmapBuffer(GLES30.GL_TRANSFORM_FEEDBACK_BUFFER);

      GLES30.glBindBuffer(GLES30.GL_ARRAY_BUFFER, 0);

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    public void onSurfaceChanged(GL10 glUnused, int width, int height) 

      { 

      }

///////////////////////////////////////////////////////////////////////////////////////////////////

    public void onSurfaceCreated(GL10 glUnused, EGLConfig config) 

      {

      try

        {

        Distorted.onCreate(mView.getContext());

        }

      catch(Exception ex)

        {

        android.util.Log.e("Feedback", ex.getMessage() );

        }

      final Resources resources = mView.getContext().getResources();

      final InputStream vertStream = resources.openRawResource(org.distorted.library.R.raw.feedback_vertex_shader);

      final InputStream fragStream = resources.openRawResource(org.distorted.library.R.raw.feedback_fragment_shader);

      int glsl = 300;

      String header= "#version 300 es\n";

      String[] feedback = { "outValue" };

      try

        {

        mFeedbackProgram = new DistortedProgram(vertStream,fragStream, header, header, glsl, feedback );

        }

      catch(Exception ex)

        {

        android.util.Log.e("Feedback", "exception creating feedback program: "+ex.getMessage());

        }

      float[] floatData = { 1.0f,4.0f,9.0f, 16.0f,25.0f,36.0f, 49.0f,64.0f,81.0f,  100.0f,121.0f,144.0f};

      mVertices = floatData.length/POSITION;

      FloatBuffer data = ByteBuffer.allocateDirect(mVertices*POSITION*BYTESFLOAT).order(ByteOrder.nativeOrder()).asFloatBuffer();

      data.put(floatData).position(0);

      mVBO = new int[1];

      GLES30.glGenBuffers(1, mVBO, 0);

      GLES30.glBindBuffer(GLES30.GL_ARRAY_BUFFER, mVBO[0]);

      GLES30.glBufferData(GLES30.GL_ARRAY_BUFFER, mVertices*POSITION*BYTESFLOAT, data, GLES30.GL_STATIC_DRAW);

      GLES30.glBindBuffer(GLES30.GL_ARRAY_BUFFER, 0);

      mTBO = new int[1];

      GLES30.glGenBuffers(1, mTBO, 0);

      GLES30.glBindBuffer(GLES30.GL_TRANSFORM_FEEDBACK_BUFFER, mTBO[0]);

      GLES30.glBufferData(GLES30.GL_TRANSFORM_FEEDBACK_BUFFER, 3*(mVertices)*POSITION*BYTESFLOAT, null, GLES30.GL_STATIC_READ);

      GLES30.glBindBuffer(GLES30.GL_TRANSFORM_FEEDBACK_BUFFER, 0);

      }

}