Distorted Android

import android.content.res.Resources;

import android.opengl.GLES31;

import android.util.Log;

import org.distorted.library.R;

import org.distorted.library.effect.FragmentEffect;

import org.distorted.library.effect.VertexEffect;

import org.distorted.library.mesh.MeshBase;

import org.distorted.library.program.DistortedProgram;

import java.io.InputStream;

import java.nio.ByteBuffer;

import java.nio.ByteOrder;

import java.nio.FloatBuffer;

import java.nio.IntBuffer;

  /// MAIN PROGRAM ///

  private static DistortedProgram mMainProgram;

  private static int mMainTextureH;

  /// BLIT PROGRAM ///

  private static DistortedProgram mBlitProgram;

  private static int mBlitTextureH;

  private static int mBlitDepthH;

  private static final FloatBuffer mQuadPositions;

  static

    {

    float[] positionData= { -0.5f, -0.5f,  -0.5f, 0.5f,  0.5f,-0.5f,  0.5f, 0.5f };

    mQuadPositions = ByteBuffer.allocateDirect(32).order(ByteOrder.nativeOrder()).asFloatBuffer();

    mQuadPositions.put(positionData).position(0);

    }

  /// BLIT DEPTH PROGRAM ///

  private static DistortedProgram mBlitDepthProgram;

  private static int mBlitDepthTextureH;

  private static int mBlitDepthDepthTextureH;

  private static int mBlitDepthDepthH;

  private static int mBlitDepthTexCorrH;

  /// NORMAL PROGRAM /////

  private static DistortedProgram mNormalProgram;

  private static int mNormalMVPMatrixH;

  /// OIT SSBO BUFFER ///

  private static int[] mLinkedListSSBO = new int[1];

  private static int[] mAtomicCounter = new int[Distorted.FBO_QUEUE_SIZE];

  private static int   mCurrBuffer;

  static

    {

    mLinkedListSSBO[0]= -1;

    mCurrBuffer       =  0;

    for(int i=0; i<Distorted.FBO_QUEUE_SIZE; i++)  mAtomicCounter[i] = -1;

    }

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

  // meaning: allocate 1.0 screenful of places for transparent

  // fragments in the SSBO backing up the OIT render method.

  private static float mBufferSize=1.0f;

  /// OIT CLEAR PROGRAM ///

  private static DistortedProgram mOITClearProgram;

  private static int mOITClearDepthH;

  private static int mOITClearTexCorrH;

  private static int mOITClearSizeH;

  /// OIT BUILD PROGRAM ///

  private static DistortedProgram mOITBuildProgram;

  private static int mOITBuildTextureH;

  private static int mOITBuildDepthTextureH;

  private static int mOITBuildDepthH;

  private static int mOITBuildTexCorrH;

  private static int mOITBuildSizeH;

  private static int mOITBuildNumRecordsH;

  /// OIT COLLAPSE PROGRAM ///

  private static DistortedProgram mOITCollapseProgram;

  private static int mOITCollapseDepthTextureH;

  private static int mOITCollapseDepthH;

  private static int mOITCollapseTexCorrH;

  private static int mOITCollapseSizeH;

  /// OIT RENDER PROGRAM ///

  private static DistortedProgram mOITRenderProgram;

  private static int mOITRenderDepthH;

  private static int mOITRenderTexCorrH;

  private static int mOITRenderSizeH;

  /// MAIN OIT PROGRAM ///

  private static DistortedProgram mMainOITProgram;

  private static int mMainOITTextureH;

  private static int mMainOITSizeH;

  private static int mMainOITNumRecordsH;

  /// END PROGRAMS //////

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

  static void createPrograms(Resources resources)

    {

    // MAIN PROGRAM ////////////////////////////////////

    final InputStream mainVertStream = resources.openRawResource(R.raw.main_vertex_shader);

    final InputStream mainFragStream = resources.openRawResource(R.raw.main_fragment_shader);

    int numF = FragmentEffect.getNumEnabled();

    int numV = VertexEffect.getNumEnabled();

    String mainVertHeader= Distorted.GLSL_VERSION + ("#define NUM_VERTEX "   + ( numV>0 ? getMax(EffectType.VERTEX  ) : 0 ) + "\n");

    String mainFragHeader= Distorted.GLSL_VERSION + ("#define NUM_FRAGMENT " + ( numF>0 ? getMax(EffectType.FRAGMENT) : 0 ) + "\n");

    String enabledEffectV= VertexEffect.getGLSL();

    String enabledEffectF= FragmentEffect.getGLSL();

    String[] feedback = { "v_Position", "v_endPosition" };

    try

      {

      mMainProgram = new DistortedProgram(mainVertStream, mainFragStream, mainVertHeader, mainFragHeader,

                                          enabledEffectV, enabledEffectF, Distorted.GLSL, feedback);

      }

    catch(Exception e)

      {

      Log.e("EFFECTS", e.getClass().getSimpleName()+" trying to compile MAIN program: "+e.getMessage());

      throw new RuntimeException(e.getMessage());

      }

    int mainProgramH = mMainProgram.getProgramHandle();

    EffectQueue.getUniforms(mainProgramH,0);

    mMainTextureH= GLES31.glGetUniformLocation( mainProgramH, "u_Texture");

    // BLIT PROGRAM ////////////////////////////////////

    final InputStream blitVertStream = resources.openRawResource(R.raw.blit_vertex_shader);

    final InputStream blitFragStream = resources.openRawResource(R.raw.blit_fragment_shader);

    try

      {

      mBlitProgram = new DistortedProgram(blitVertStream,blitFragStream,Distorted.GLSL_VERSION,Distorted.GLSL_VERSION, Distorted.GLSL);

      }

    catch(Exception e)

      {

      Log.e("EFFECTS", e.getClass().getSimpleName()+" trying to compile BLIT program: "+e.getMessage());

      throw new RuntimeException(e.getMessage());

      }

    int blitProgramH = mBlitProgram.getProgramHandle();

    mBlitTextureH  = GLES31.glGetUniformLocation( blitProgramH, "u_Texture");

    mBlitDepthH    = GLES31.glGetUniformLocation( blitProgramH, "u_Depth");

    // BLIT DEPTH PROGRAM ////////////////////////////////////

    final InputStream blitDepthVertStream = resources.openRawResource(R.raw.blit_depth_vertex_shader);

    final InputStream blitDepthFragStream = resources.openRawResource(R.raw.blit_depth_fragment_shader);

    try

      {

      mBlitDepthProgram = new DistortedProgram(blitDepthVertStream,blitDepthFragStream,Distorted.GLSL_VERSION,Distorted.GLSL_VERSION, Distorted.GLSL);

      }

    catch(Exception e)

      {

      Log.e("EFFECTS", e.getClass().getSimpleName()+" trying to compile BLIT DEPTH program: "+e.getMessage());

      throw new RuntimeException(e.getMessage());

      }

    int blitDepthProgramH   = mBlitDepthProgram.getProgramHandle();

    mBlitDepthTextureH      = GLES31.glGetUniformLocation( blitDepthProgramH, "u_Texture");

    mBlitDepthDepthTextureH = GLES31.glGetUniformLocation( blitDepthProgramH, "u_DepthTexture");

    mBlitDepthDepthH        = GLES31.glGetUniformLocation( blitDepthProgramH, "u_Depth");

    mBlitDepthTexCorrH      = GLES31.glGetUniformLocation( blitDepthProgramH, "u_TexCorr");

    // NORMAL PROGRAM //////////////////////////////////////

    final InputStream normalVertexStream   = resources.openRawResource(R.raw.normal_vertex_shader);

    final InputStream normalFragmentStream = resources.openRawResource(R.raw.normal_fragment_shader);

    try

      {

      mNormalProgram = new DistortedProgram(normalVertexStream,normalFragmentStream, Distorted.GLSL_VERSION, Distorted.GLSL_VERSION, Distorted.GLSL);

      }

    catch(Exception e)

      {

      Log.e("EFFECTS", e.getClass().getSimpleName()+" trying to compile NORMAL program: "+e.getMessage());

      throw new RuntimeException(e.getMessage());

      }

    int normalProgramH = mNormalProgram.getProgramHandle();

    mNormalMVPMatrixH  = GLES31.glGetUniformLocation( normalProgramH, "u_MVPMatrix");

    }

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

  static void createProgramsOIT(Resources resources)

    {

    // MAIN OIT PROGRAM ////////////////////////////////

    final InputStream mainVertStream = resources.openRawResource(R.raw.main_vertex_shader);

    final InputStream mainFragStream = resources.openRawResource(R.raw.main_fragment_shader);

    int numF = FragmentEffect.getNumEnabled();

    int numV = VertexEffect.getNumEnabled();

    String mainVertHeader= Distorted.GLSL_VERSION +

                           ("#define NUM_VERTEX "   + ( numV>0 ? getMax(EffectType.VERTEX  ) : 0 ) + "\n") +

                           ("#define OIT\n");

    String mainFragHeader= Distorted.GLSL_VERSION +

                           ("#define NUM_FRAGMENT " + ( numF>0 ? getMax(EffectType.FRAGMENT) : 0 ) + "\n") +

                           ("#define OIT\n");

    String enabledEffectV= VertexEffect.getGLSL();

    String enabledEffectF= FragmentEffect.getGLSL();

    try

      {

      mMainOITProgram = new DistortedProgram(mainVertStream, mainFragStream, mainVertHeader, mainFragHeader,

                                             enabledEffectV, enabledEffectF, Distorted.GLSL, null);

      }

    catch(Exception e)

      {

      Log.e("EFFECTS", e.getClass().getSimpleName()+" trying to compile MAIN OIT program: "+e.getMessage());

      throw new RuntimeException(e.getMessage());

      }

    int mainOITProgramH = mMainOITProgram.getProgramHandle();

    EffectQueue.getUniforms(mainOITProgramH,1);

    mMainOITTextureH    = GLES31.glGetUniformLocation( mainOITProgramH, "u_Texture");

    mMainOITSizeH       = GLES31.glGetUniformLocation( mainOITProgramH, "u_Size");

    mMainOITNumRecordsH = GLES31.glGetUniformLocation( mainOITProgramH, "u_numRecords");

    // OIT CLEAR PROGRAM ////////////////////////////////////

    final InputStream oitClearVertStream = resources.openRawResource(R.raw.oit_vertex_shader);

    final InputStream oitClearFragStream = resources.openRawResource(R.raw.oit_clear_fragment_shader);

    try

      {

      mOITClearProgram = new DistortedProgram(oitClearVertStream,oitClearFragStream,Distorted.GLSL_VERSION,Distorted.GLSL_VERSION, Distorted.GLSL);

      }

    catch(Exception e)

      {

      Log.e("EFFECTS", e.getClass().getSimpleName()+" trying to compile OIT CLEAR program: "+e.getMessage());

      throw new RuntimeException(e.getMessage());

      }

    int oitClearProgramH   = mOITClearProgram.getProgramHandle();

    mOITClearDepthH        = GLES31.glGetUniformLocation( oitClearProgramH, "u_Depth");

    mOITClearTexCorrH      = GLES31.glGetUniformLocation( oitClearProgramH, "u_TexCorr");

    mOITClearSizeH         = GLES31.glGetUniformLocation( oitClearProgramH, "u_Size");

    // OIT BUILD PROGRAM ////////////////////////////////////

    final InputStream oitBuildVertStream = resources.openRawResource(R.raw.oit_vertex_shader);

    final InputStream oitBuildFragStream = resources.openRawResource(R.raw.oit_build_fragment_shader);

    try

      {

      mOITBuildProgram = new DistortedProgram(oitBuildVertStream,oitBuildFragStream,Distorted.GLSL_VERSION,Distorted.GLSL_VERSION, Distorted.GLSL);

      }

    catch(Exception e)

      {

      Log.e("EFFECTS", e.getClass().getSimpleName()+" trying to compile OIT BUILD program: "+e.getMessage());

      throw new RuntimeException(e.getMessage());

      }

    int oitBuildProgramH   = mOITBuildProgram.getProgramHandle();

    mOITBuildTextureH      = GLES31.glGetUniformLocation( oitBuildProgramH, "u_Texture");

    mOITBuildDepthTextureH = GLES31.glGetUniformLocation( oitBuildProgramH, "u_DepthTexture");

    mOITBuildDepthH        = GLES31.glGetUniformLocation( oitBuildProgramH, "u_Depth");

    mOITBuildTexCorrH      = GLES31.glGetUniformLocation( oitBuildProgramH, "u_TexCorr");

    mOITBuildSizeH         = GLES31.glGetUniformLocation( oitBuildProgramH, "u_Size");

    mOITBuildNumRecordsH   = GLES31.glGetUniformLocation( oitBuildProgramH, "u_numRecords");

    // OIT COLLAPSE PROGRAM ///////////////////////////

    final InputStream oitCollapseVertStream = resources.openRawResource(R.raw.oit_vertex_shader);

    final InputStream oitCollapseFragStream = resources.openRawResource(R.raw.oit_collapse_fragment_shader);

    try

      {

      mOITCollapseProgram = new DistortedProgram(oitCollapseVertStream,oitCollapseFragStream,Distorted.GLSL_VERSION,Distorted.GLSL_VERSION, Distorted.GLSL);

      }

    catch(Exception e)

      {

      Log.e("EFFECTS", e.getClass().getSimpleName()+" trying to compile OIT COLLAPSE program: "+e.getMessage());

      throw new RuntimeException(e.getMessage());

      }

    int oitCollapseProgramH   = mOITCollapseProgram.getProgramHandle();

    mOITCollapseDepthTextureH = GLES31.glGetUniformLocation( oitCollapseProgramH, "u_DepthTexture");

    mOITCollapseDepthH        = GLES31.glGetUniformLocation( oitCollapseProgramH, "u_Depth");

    mOITCollapseTexCorrH      = GLES31.glGetUniformLocation( oitCollapseProgramH, "u_TexCorr");

    mOITCollapseSizeH         = GLES31.glGetUniformLocation( oitCollapseProgramH, "u_Size");

    // OIT RENDER PROGRAM ///////////////////////////

    final InputStream oitRenderVertStream = resources.openRawResource(R.raw.oit_vertex_shader);

    final InputStream oitRenderFragStream = resources.openRawResource(R.raw.oit_render_fragment_shader);

    try

      {

      mOITRenderProgram = new DistortedProgram(oitRenderVertStream,oitRenderFragStream,Distorted.GLSL_VERSION,Distorted.GLSL_VERSION, Distorted.GLSL);

      }

    catch(Exception e)

      {

      Log.e("EFFECTS", e.getClass().getSimpleName()+" trying to compile OIT RENDER program: "+e.getMessage());

      throw new RuntimeException(e.getMessage());

      }

    int oitRenderProgramH   = mOITRenderProgram.getProgramHandle();

    mOITRenderDepthH        = GLES31.glGetUniformLocation( oitRenderProgramH, "u_Depth");

    mOITRenderTexCorrH      = GLES31.glGetUniformLocation( oitRenderProgramH, "u_TexCorr");

    mOITRenderSizeH         = GLES31.glGetUniformLocation( oitRenderProgramH, "u_Size");

    }

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

  private void displayNormals(MeshBase mesh)

    {

    int num = mesh.getNumVertices();

    int tfo = mesh.getTFO();

    GLES31.glBindBufferBase(GLES31.GL_TRANSFORM_FEEDBACK_BUFFER, 0, tfo );

    GLES31.glBeginTransformFeedback( GLES31.GL_POINTS);

    DistortedRenderState.switchOffDrawing();

    GLES31.glDrawArrays( GLES31.GL_POINTS, 0, num );

    DistortedRenderState.restoreDrawing();

    GLES31.glEndTransformFeedback();

    GLES31.glBindBufferBase(GLES31.GL_TRANSFORM_FEEDBACK_BUFFER, 0, 0);

    mNormalProgram.useProgram();

    GLES31.glUniformMatrix4fv(mNormalMVPMatrixH, 1, false, EffectQueue.getMVP(mQueues) , 0);

    mesh.bindTransformAttribs(mNormalProgram);

    GLES31.glLineWidth(8.0f);

    GLES31.glDrawArrays(GLES31.GL_LINES, 0, 2*num);

    }

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

  void drawPrivOIT(float halfW, float halfH, MeshBase mesh, DistortedOutputSurface surface, long currTime)

    {

    float halfZ = halfW*mesh.getZFactor();

    EffectQueue.compute(mQueues, currTime, halfW, halfH, halfZ );

    GLES31.glViewport(0, 0, surface.mWidth, surface.mHeight );

    mMainOITProgram.useProgram();

    GLES31.glUniform1i(mMainOITTextureH, 0);

    GLES31.glUniform2ui(mMainOITSizeH, surface.mWidth, surface.mHeight);

    GLES31.glUniform1ui(mMainOITNumRecordsH, (int)(mBufferSize*surface.mWidth*surface.mHeight) );

    mesh.bindVertexAttribs(mMainOITProgram);

    float inflate = mesh.getInflate();

    EffectQueue.send(mQueues, surface, inflate, halfW, halfH, halfZ, 1 );

    GLES31.glDrawArrays(GLES31.GL_TRIANGLE_STRIP, 0, mesh.getNumVertices() );

    if( mesh.getShowNormals() )

      {

      mMainProgram.useProgram();

      EffectQueue.send(mQueues, surface, inflate, halfW, halfH, halfZ, 0 );

      displayNormals(mesh);

      }

    }

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

  void drawPriv(float halfW, float halfH, MeshBase mesh, DistortedOutputSurface surface, long currTime)

    {

    float halfZ = halfW*mesh.getZFactor();

    EffectQueue.compute(mQueues, currTime, halfW, halfH, halfZ );

    GLES31.glViewport(0, 0, surface.mWidth, surface.mHeight );

    mMainProgram.useProgram();

    GLES31.glUniform1i(mMainTextureH, 0);

    mesh.bindVertexAttribs(mMainProgram);

    EffectQueue.send(mQueues, surface, mesh.getInflate(), halfW, halfH, halfZ, 0 );

    GLES31.glDrawArrays(GLES31.GL_TRIANGLE_STRIP, 0, mesh.getNumVertices() );

    if( mesh.getShowNormals() ) displayNormals(mesh);

    }

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

  static void blitPriv(DistortedOutputSurface surface)

    {

    mBlitProgram.useProgram();

    GLES31.glViewport(0, 0, surface.mWidth, surface.mHeight );

    GLES31.glUniform1i(mBlitTextureH, 0);

    GLES31.glUniform1f( mBlitDepthH , 1.0f-surface.mNear);

    GLES31.glVertexAttribPointer(mBlitProgram.mAttribute[0], 2, GLES31.GL_FLOAT, false, 0, mQuadPositions);

    GLES31.glDrawArrays(GLES31.GL_TRIANGLE_STRIP, 0, 4);

    }

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

  static void blitDepthPriv(DistortedOutputSurface surface, float corrW, float corrH)

    {

    mBlitDepthProgram.useProgram();

    GLES31.glViewport(0, 0, surface.mWidth, surface.mHeight );

    GLES31.glUniform1i(mBlitDepthTextureH, 0);

    GLES31.glUniform1i(mBlitDepthDepthTextureH, 1);

    GLES31.glUniform2f(mBlitDepthTexCorrH, corrW, corrH );

    GLES31.glUniform1f( mBlitDepthDepthH , 1.0f-surface.mNear);

    GLES31.glVertexAttribPointer(mBlitDepthProgram.mAttribute[0], 2, GLES31.GL_FLOAT, false, 0, mQuadPositions);

    GLES31.glDrawArrays(GLES31.GL_TRIANGLE_STRIP, 0, 4);

    }

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

  private static int printPreviousBuffer()

    {

    int counter = 0;

    ByteBuffer atomicBuf = (ByteBuffer)GLES31.glMapBufferRange( GLES31.GL_ATOMIC_COUNTER_BUFFER, 0, 4,

                                                                GLES31.GL_MAP_READ_BIT);

    if( atomicBuf!=null )

      {

      IntBuffer atomicIntBuf = atomicBuf.order(ByteOrder.nativeOrder()).asIntBuffer();

      counter = atomicIntBuf.get(0);

      }

    else

      {

      android.util.Log.e("effects", "print: failed to map atomic buffer");

      }

    GLES31.glUnmapBuffer(GLES31.GL_ATOMIC_COUNTER_BUFFER);

    return counter;

    }

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

  private static void zeroBuffer()

    {

    ByteBuffer atomicBuf = (ByteBuffer)GLES31.glMapBufferRange( GLES31.GL_ATOMIC_COUNTER_BUFFER, 0, 4,

        GLES31.GL_MAP_WRITE_BIT|GLES31.GL_MAP_INVALIDATE_BUFFER_BIT);

    if( atomicBuf!=null )

      {

      IntBuffer atomicIntBuf = atomicBuf.order(ByteOrder.nativeOrder()).asIntBuffer();

      atomicIntBuf.put(0,0);

      }

    else

      {

      android.util.Log.e("effects", "zero: failed to map atomic buffer");

      }

    GLES31.glUnmapBuffer(GLES31.GL_ATOMIC_COUNTER_BUFFER);

    }

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

// reset atomic counter to 0

  static int zeroOutAtomic()

    {

    int counter = 0;

    if( mAtomicCounter[0]<0 )

      {

      GLES31.glGenBuffers(Distorted.FBO_QUEUE_SIZE,mAtomicCounter,0);

      for(int i=0; i<Distorted.FBO_QUEUE_SIZE; i++)

        {

        GLES31.glBindBuffer(GLES31.GL_ATOMIC_COUNTER_BUFFER, mAtomicCounter[i]);

        GLES31.glBufferData(GLES31.GL_ATOMIC_COUNTER_BUFFER, 4, null, GLES31.GL_DYNAMIC_DRAW);

        zeroBuffer();

        }

      }

    // reading the value of the buffer on every frame would slow down rendering by

    // about 3%; doing it only once every 5 frames affects speed by less than 1%.

    if( mCurrBuffer==0 )

      {

      GLES31.glBindBufferBase(GLES31.GL_ATOMIC_COUNTER_BUFFER, 0, mAtomicCounter[mCurrBuffer]);

      counter = printPreviousBuffer();

      }

    if( ++mCurrBuffer>=Distorted.FBO_QUEUE_SIZE ) mCurrBuffer = 0;

    GLES31.glBindBufferBase(GLES31.GL_ATOMIC_COUNTER_BUFFER, 0, mAtomicCounter[mCurrBuffer]);

    zeroBuffer();

    return counter;

    }

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

// Pass1 of the OIT algorithm. Clear per-pixel head-poiners.

  static void oitClear(DistortedOutputSurface surface, int counter)

    {

    if( mLinkedListSSBO[0]<0 )

      {

      GLES31.glGenBuffers(1,mLinkedListSSBO,0);

      int size = (int)(surface.mWidth*surface.mHeight*(3*mBufferSize+1)*4);

      GLES31.glBindBuffer(GLES31.GL_SHADER_STORAGE_BUFFER, mLinkedListSSBO[0]);

      GLES31.glBufferData(GLES31.GL_SHADER_STORAGE_BUFFER, size, null, GLES31.GL_DYNAMIC_READ|GLES31.GL_DYNAMIC_DRAW);

      GLES31.glBindBuffer(GLES31.GL_SHADER_STORAGE_BUFFER, 0);

      GLES31.glBindBufferBase(GLES31.GL_SHADER_STORAGE_BUFFER, 1, mLinkedListSSBO[0]);

      }

    // See if we have overflown the SSBO in one of the previous frames.

    // If yes, assume we need to make the SSBO larger.

    float overflow = counter/(mBufferSize*surface.mWidth*surface.mHeight);

    if( overflow>1.0f )

      {

      //android.util.Log.e("effects", "previous frame rendered "+counter+

      //                   " fragments, but there was only "+(mBufferSize*surface.mWidth*surface.mHeight)+" space");

      mBufferSize *= (int)(overflow+1.0f);

      int size = (int)(surface.mWidth*surface.mHeight*(3*mBufferSize+1)*4);

      GLES31.glBindBuffer(GLES31.GL_SHADER_STORAGE_BUFFER, mLinkedListSSBO[0]);

      GLES31.glBufferData(GLES31.GL_SHADER_STORAGE_BUFFER, size, null, GLES31.GL_DYNAMIC_READ|GLES31.GL_DYNAMIC_DRAW);

      GLES31.glBindBuffer(GLES31.GL_SHADER_STORAGE_BUFFER, 0);

      }

    mOITClearProgram.useProgram();

    GLES31.glViewport(0, 0, surface.mWidth, surface.mHeight );

    GLES31.glUniform2f(mOITClearTexCorrH, 1.0f, 1.0f );   // corrections do not really matter here - only present because of common vertex shader.

    GLES31.glUniform1f( mOITClearDepthH , 1.0f);          // likewise depth

    GLES31.glUniform2ui(mOITClearSizeH, surface.mWidth, surface.mHeight);

    GLES31.glVertexAttribPointer(mOITClearProgram.mAttribute[0], 2, GLES31.GL_FLOAT, false, 0, mQuadPositions);

    GLES31.glDrawArrays(GLES31.GL_TRIANGLE_STRIP, 0, 4);

    }

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

// Pass2 of the OIT algorithm - build per-pixel linked lists.

  static void oitBuild(DistortedOutputSurface surface, float corrW, float corrH)

    {

    mOITBuildProgram.useProgram();

    GLES31.glViewport(0, 0, surface.mWidth, surface.mHeight );

    GLES31.glUniform1i(mOITBuildTextureH, 0);

    GLES31.glUniform1i(mOITBuildDepthTextureH, 1);

    GLES31.glUniform2f(mOITBuildTexCorrH, corrW, corrH );

    GLES31.glUniform2ui(mOITBuildSizeH, surface.mWidth, surface.mHeight);

    GLES31.glUniform1ui(mOITBuildNumRecordsH, (int)(mBufferSize*surface.mWidth*surface.mHeight) );

    GLES31.glUniform1f(mOITBuildDepthH , 1.0f-surface.mNear);

    GLES31.glVertexAttribPointer(mOITBuildProgram.mAttribute[0], 2, GLES31.GL_FLOAT, false, 0, mQuadPositions);

    GLES31.glDrawArrays(GLES31.GL_TRIANGLE_STRIP, 0, 4);

    }

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

// Pass3 of the OIT algorithm. Cut occluded parts of the linked list.

  static void oitCollapse(DistortedOutputSurface surface, float corrW, float corrH)

    {

    mOITCollapseProgram.useProgram();

    GLES31.glViewport(0, 0, surface.mWidth, surface.mHeight );

    GLES31.glUniform1i(mOITCollapseDepthTextureH, 1);

    GLES31.glUniform2f(mOITCollapseTexCorrH, corrW, corrH );

    GLES31.glUniform2ui(mOITCollapseSizeH, surface.mWidth, surface.mHeight);

    GLES31.glUniform1f( mOITCollapseDepthH , 1.0f-surface.mNear);

    GLES31.glVertexAttribPointer(mOITCollapseProgram.mAttribute[0], 2, GLES31.GL_FLOAT, false, 0, mQuadPositions);

    GLES31.glDrawArrays(GLES31.GL_TRIANGLE_STRIP, 0, 4);

    }

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

// Pass4 of the OIT algorithm. Render all the transparent pixels from the per-pixel linked lists.

  static void oitRender(DistortedOutputSurface surface, float corrW, float corrH)

    {

    mOITRenderProgram.useProgram();

    GLES31.glViewport(0, 0, surface.mWidth, surface.mHeight );

    GLES31.glUniform2f(mOITRenderTexCorrH, corrW, corrH );

    GLES31.glUniform2ui(mOITRenderSizeH, surface.mWidth, surface.mHeight);

    GLES31.glUniform1f( mOITRenderDepthH , 1.0f-surface.mNear);

    GLES31.glVertexAttribPointer(mOITRenderProgram.mAttribute[0], 2, GLES31.GL_FLOAT, false, 0, mQuadPositions);

    GLES31.glDrawArrays(GLES31.GL_TRIANGLE_STRIP, 0, 4);

    }

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

  static void onPause()

    {

    mLinkedListSSBO[0]= -1;

    for(int i=0; i<Distorted.FBO_QUEUE_SIZE; i++) mAtomicCounter[i] = -1;

    }

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

  static void setSSBOSize(float size)

    {

    mBufferSize = size;

    }

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

/**

 * Returns the maximum number of effects of a given type that can be simultaneously applied to a

 * single (InputSurface,MeshBase) combo.

 *

 * @param type {@link EffectType}

 * @return The maximum number of effects of a given type.

 */

  @SuppressWarnings("unused")

  public static int getMax(EffectType type)

    {

    return EffectQueue.getMax(type.ordinal());

    }

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

/**

 * Sets the maximum number of effects that can be stored in a single EffectQueue at one time.

 * This can fail if:

 * <ul>

 * <li>the value of 'max' is outside permitted range (0 &le; max &le; Byte.MAX_VALUE)

 * <li>We try to increase the value of 'max' when it is too late to do so already. It needs to be called

 *     before the Vertex Shader gets compiled, i.e. before the call to {@link Distorted#onCreate}. After this

 *     time only decreasing the value of 'max' is permitted.

 * <li>Furthermore, this needs to be called before any instances of the DistortedEffects class get created.

 * </ul>

 *

 * @param type {@link EffectType}

 * @param max new maximum number of simultaneous effects. Has to be a non-negative number not greater

 *            than Byte.MAX_VALUE

 * @return <code>true</code> if operation was successful, <code>false</code> otherwise.

 */

  @SuppressWarnings("unused")

  public static boolean setMax(EffectType type, int max)

    {

    return EffectQueue.setMax(type.ordinal(),max);

    }