Hi all,
I'm working on Opengl ES 2.0 using OMAP3530 development board on Windows CE 7.

My Task is to Load a 24-Bit Image File & rotate it about an angle in z-Axis & export the image file(Buffer).

For this task I've created a FBO for off-screen rendering & loaded this image file as a Texture by using glTexImage2D() & I've applied this Texture to a Quad & rotate that QUAD by using PVRTMat4::RotationZ() API & Read-Back by using ReadPixels() API. Since it is a single frame process i just made only 1 loop.

Here are the problems I'm facing now.
1) All API's are taking distinct processing time on every run.ie Sometimes when i run my application i get different processing time for all API's.

2) glDrawArrays() is taking too much time (~50 ms - 80 ms)

3) glReadPixels() is also taking too much time ~95 ms for Image(800x600)

4) Loading 32-Bit image is much faster than 24-Bit image so conversion is needed.

I'd like to ask you all if anybody facing/Solved similar problem kindly suggest me any

Here is the Code snippet of my Application.
[code]
void BindTexture(){
glGenTextures(1, &m_uiTexture);
glBindTexture(GL_TEXTURE_2D, m_uiTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, ImageWidth, ImageHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, pTexData);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_LINEAR );
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, TCHAR *lpCmdLine, int nCmdShow)
{
// Fragment and vertex shaders code
char* pszFragShader = "Same as in RenderToTexture sample;
char* pszVertShader = "Same as in RenderToTexture sample;

CreateWindow(Imagewidth, ImageHeight);//For this i've referred OGLES2HelloTriangle_Windows.cpp example
LoadImageBuffers();
BindTexture();

Generate& BindFrame,Render Buffer();
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_auiFbo, 0);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, ImageWidth, ImageHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, m_auiDepthBuffer);
BindTexture();

GLfloat Angle = 0.02f;
GLfloat afVertices[] = {Vertices to Draw a QUAD};

glGenBuffers(1, &ui32Vbo);
LoadVBO's();//Aps's to load VBO's refer

// Draws a triangle for 1 frames
while(g_bDemoDone==false)
{
glBindFramebuffer(GL_FRAMEBUFFER, m_auiFbo);
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

PVRTMat4 mRot,mTrans, mMVP;
mTrans = PVRTMat4::Translation(0,0,0);
mRot = PVRTMat4::RotationZ(Angle);

glBindBuffer(GL_ARRAY_BUFFER, ui32Vbo);
glDisable(GL_CULL_FACE);

int i32Location = glGetUniformLocation(uiProgramObject, "myPMVMatrix");
mMVP = mTrans * mRot ;

glUniformMatrix4fv(i32Location, 1, GL_FALSE, mMVP.ptr());

// Pass the vertex data
glEnableVertexAttribArray(VERTEX_ARRAY);
glVertexAttribPointer(VERTEX_ARRAY, 3, GL_FLOAT, GL_FALSE, m_ui32VertexStride, 0);

// Pass the texture coordinates data
glEnableVertexAttribArray(TEXCOORD_ARRAY);
glVertexAttribPointer(TEXCOORD_ARRAY, 2, GL_FLOAT, GL_FALSE, m_ui32VertexStride, (void*) (3 * sizeof(GLfloat)));

glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);//

glReadPixels(0,0,ImageWidth ,ImageHeight,GL_RGBA,GL_UNSIGNED_BYTE,pOutTexData) ;

glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindFramebuffer(GL_FRAMEBUFFER, 0);

eglSwapBuffers(eglDisplay, eglSurface);

}

DeInitAll();
[\code]