I have a byte array of RGB values, just like the contents(without header) of a *.bmp file. What I want to do is, draw the corresponding bitmap on Android, using OpenGL.
It seems that OpenGL ES doesn't have a single API that will do, it true?
If true, how can I do this?
PS: Actually, I can draw it in JAVA code, but it's too slow and costs too much CPU time. So I want to try drawing it with OpenGL. Is there any other advises? Or maybe OpenGL can't be the right answer?
Thank you all!
I'm not sure the answers you got were related to the question you asked. I believe I had the same question, however I was not interested in drawing a bitmap on the screen, I was rather interested in creating (drawing on) a bitmap fast, using GL instead of java computations. Since I could find no reply to my question anywhere on the web I just started reading the GL API's and the way I solved my problem was by reading the pixels drawn by my onDrawFrame method with glReadPixels after turning on a 'grabdata' flag, somewhere else in the program, something like this:
// imports
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import javax.microedition.khronos.opengles.GL10;
import android.graphics.Bitmap;
import android.opengl.GLES20;
//somewhere inside the class that implements GLSurfaceView.Renderer:
ByteBuffer data;
private int height;
private int width;
boolean grabdata=false;
public void onSurfaceChanged(GL10 glUnused, int width, int height) {
this.width=width;
this.height=height;
data=ByteBuffer.allocateDirect(width*height*4).order(ByteOrder.nativeOrder());
/*
......
prepare the surface
.......
*/
}
public void onDrawFrame(GL10 glUnused) {
/*
actually draw whatever you want, set matrices, rotate, draw etc...
drawTriangle(mTriangleVertices);
.
.
.
*/
if (grabdata) {
GLES20.glReadPixels(0,0,width, height, GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE,data);
grabdata=false; //until we want to read again
//create a bitmap now if you havent prepared it somewhere else.
Bitmap.Config conf = Bitmap.Config.ARGB_8888;
Bitmap bitmap = Bitmap.createBitmap(width, height, conf);
bitmap.copyPixelsFromBuffer(data);
//do something with it....
// storeImage(bitmap);
data.clear();
}
}