Develop Reference

opengl es multi-pass blurring the second pass overrides the first pass

I am not very good with opengl es so any beginner mistake in the code is justified. I have implemented the draw function to execute the same fragment shader with different uniform variable called blurringDirection, if I execute the horizontal blurring alone(by setting the blurringDirection to 0) it works fine, also the same for the vertical but when I try to combine them together the second overrides the first. Here is my draw() function:
fun draw(
mvpMatrix: FloatArray?,
vertexBuffer: FloatBuffer?,
firstVertex: Int,
vertexCount: Int,
coordsPerVertex: Int,
vertexStride: Int,
texMatrix: FloatArray?,
texBuffer: FloatBuffer?,
textureId: Int,
texStride: Int,
) {
//creating an intermediate texture
val intermediateTexIdArr = IntArray(1)
GLES20.glGenTextures(1, intermediateTexIdArr, 0)
glBindTexture(GL_TEXTURE_2D, intermediateTexIdArr[0])
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 640, 360, 0, GL_RGBA, GL_UNSIGNED_BYTE, null)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
glBindTexture(GL_TEXTURE_2D, 0)
//creating a framebuffer and attaching the newly created texture to it.
val frameBufferIdArr = IntArray(1)
GLES20.glGenFramebuffers(1, frameBufferIdArr, 0)
glBindFramebuffer(GL_FRAMEBUFFER, frameBufferIdArr[0])
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, intermediateTexIdArr[0], 0)
val status = glCheckFramebufferStatus(GL_FRAMEBUFFER)
Timber.d("KingArmstring: Framebuffer status is complete? ${status == GL_FRAMEBUFFER_COMPLETE}") //this prints true
if (status != GL_FRAMEBUFFER_COMPLETE) throw Exception("Framebuffer is not setup correctly")
//bind to the framebuffer instead of to the screen.
glBindFramebuffer(GL_FRAMEBUFFER, frameBufferIdArr[0])
glClearColor(0.0f, 0.0f, 0.0f, 1.0f)
glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT)
glEnable(GL_DEPTH_TEST)
glDepthFunc(GL_LEQUAL)
// Select the program.
glUseProgram(programHandle)
checkGlError("glUseProgram")
// Set the texture.
glActiveTexture(GL_TEXTURE0)
glBindTexture(textureTarget, textureId) //textureId is the main id that has the original image
// Copy the model / view / projection matrix over.
glUniformMatrix4fv(mvpMatrixLoc, 1, false, mvpMatrix, 0)
checkGlError("glUniformMatrix4fv")
// Copy the texture transformation matrix over.
glUniformMatrix4fv(texMatrixLoc, 1, false, texMatrix, 0)
checkGlError("glUniformMatrix4fv")
// Enable the "aPosition" vertex attribute.
glEnableVertexAttribArray(positionLoc)
checkGlError("glEnableVertexAttribArray")
// Connect vertexBuffer to "aPosition".
glVertexAttribPointer(
positionLoc, coordsPerVertex,
GL_FLOAT, false, vertexStride, vertexBuffer
)
checkGlError("glVertexAttribPointer")
// Enable the "aTextureCoord" vertex attribute.
glEnableVertexAttribArray(textureCoordLoc)
checkGlError("glEnableVertexAttribArray")
// Connect texBuffer to "aTextureCoord".
glVertexAttribPointer(
textureCoordLoc, 2,
GL_FLOAT, false, texStride, texBuffer
)
checkGlError("glVertexAttribPointer")
if (programType == VIDEO_STREAM) {
glUniform1f(brightnessLoc, brightness)
glUniform1f(contrastLoc, contrast)
glUniform1f(saturationLoc, saturation)
glUniform1f(gammaLoc, gamma)
glUniform1f(whiteBalanceTempLoc, whiteBalanceTemp)
glUniform1f(whiteBalanceTintLoc, whiteBalanceTint)
glUniform1f(whiteBalanceEnabledLoc, whiteBalanceEnabled)
glUniform1f(hueAdjLoc, hueAdj)
glUniform1f(hueAdjEnabledLoc, hueAdjEnabled)
glUniform1f(sharpnessLoc, sharpness)
glUniform1f(imageWidthFactorLoc, imageWidthFactor)
glUniform1f(imageHeightFactorLoc, imageHeightFactor)
}
glUniform1i(blurringDirectionLoc, 0)
// Draw the rect.
glDrawArrays(GL_TRIANGLE_STRIP, firstVertex, vertexCount)//rendering to the framebuffer with the blurringDirection = 0
checkGlError("glDrawElements")
glBindFramebuffer(GL_FRAMEBUFFER, 0)
glActiveTexture(GL_TEXTURE0)
glBindTexture(GL_TEXTURE_2D, intermediateTexIdArr[0])
glUniform1i(blurringDirectionLoc, 1)
glDrawArrays(GL_TRIANGLE_STRIP, firstVertex, vertexCount)//drawing on the screen second pass with the blurringDirection = 1.
glDisableVertexAttribArray(positionLoc)
glDisableVertexAttribArray(textureCoordLoc)
GLES20.glDeleteFramebuffers(1, frameBufferIdArr, 0)
GLES20.glDeleteTextures(1, intermediateTexIdArr, 0)
}

creating a framebuffer to take an image from external oes

I am trying to do multi pass rendering with framebuffer the issue is that the source is the camera so the texInput is not of type GL_TEXTURE_2D it is of type GL_TEXTURE_EXTERNAL_OES tho, if I use the function glTexImage2D it gives a black screen when I use that texture in the future after rendering to it without any errors glErros.
On the other hand if I don't use it(because it does not support GL_TEXTURE_EXTERNAL_OES) it gives me framebuffer status of NOT_COMPLETE
here is my code for creating the framebuffer and the texture that I want to associate to it.
fun prepareFBO() {
val intArray = IntArray(1)
glGenFramebuffers(1, intArray, 0)
fboId = intArray.first()
glGenTextures(1, intArray, 0)
texId = intArray.first()
glBindTexture(GL_TEXTURE_2D, texId)
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA,1080, 1920, 0, GL_RGBA, GL_UNSIGNED_BYTE, null)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
glBindFramebuffer(GL_FRAMEBUFFER, fboId)
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texId, 0)
val status = glCheckFramebufferStatus(GL_FRAMEBUFFER)
Log.e(TAG, "prepareFBO: ${status == GL_FRAMEBUFFER_COMPLETE}")
glBindFramebuffer(GL_FRAMEBUFFER, 0)
glBindTexture(GL_TEXTURE_2D, 0)
}
the rest is just normal glDrawArrays and glActiveTexture that already works fine when I draw directly to the default framebuffer, if needed please let me know and I will share them.
Thanks for help!
UPDATE:
I found that I need instead of using glTexImage2d I can use eglBindTexImage instead so the final code is:
fun prepareFBO() {
val intArray = IntArray(1)
glGenFramebuffers(1, intArray, 0)
fboId = intArray.first()
glBindFramebuffer(GL_FRAMEBUFFER, fboId)
glGenTextures(1, intArray, 0)
texId = intArray.first()
glBindTexture(GL_TEXTURE_EXTERNAL_OES, texId)
checkGlError("Error 1")
eglBindTexImage(eglGetCurrentDisplay(), windowSurface!!.eglSurface, EGL_BACK_BUFFER)
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_EXTERNAL_OES, texId, 0)
val status = glCheckFramebufferStatus(GL_FRAMEBUFFER)
Log.e(TAG, "prepareFBO: is status complete? => ${status == GL_FRAMEBUFFER_COMPLETE}")
}
while this looks like it makes sense, still I am getting the status of the framebuffer as not complete :/

opengl es 3 glBlitFramebuffer - copying one texture into another

I'm trying to copy a texture into another using 'glBlitFramebuffer', I'm working on the classic open gl example hello-gl2 from android ndk-samples. I changed the shaders to support texture and i can correctly render a textured triangle. I also changed the opengl es version requested on the java side so to request opengl-es3 and i updated the Cmakelists file to link the right library. After calling glBlitFramebuffer(0,0,tw, th, 0, 0, tw, th, GL_COLOR_BUFFER_BIT, GL_LINEAR); i get the after blitTexture glBlitFramebuffer() glError (0x502) error. What is the root cause for that?
Code I use:
To generate the textures:
void createTexture(GLuint &tex, int width, int height, int r){
int rowlen = width * 3;
unsigned char buf[width*3*height];
for (int i=0; i<rowlen; i+=3)
for (int j=0; j<height; j++) {
int col = ((int (i/(3*r))) + (int (j/r)))%2;
buf[i+j*rowlen] = buf[i+1+j*rowlen] = buf[i+2+j*rowlen] = col * 255;
}
glGenTextures(1, &tex);
glBindTexture(GL_TEXTURE_2D, tex);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, buf);
// set the texture wrapping/filtering options (on the currently bound texture object)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
LOGI("DEBUG C++ Texture created [%d]", tex);
}
to setup the framebuffer:
bool SetupFramebuffer(GLuint tex, int width, int height)
{
if (fb == 0)
{
glGenFramebuffers(1, &fb);
glBindFramebuffer(GL_DRAW_FRAMEBUFFER, fb);
glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
GL_TEXTURE_2D, tex, 0);
GLenum status = glCheckFramebufferStatus(GL_DRAW_FRAMEBUFFER);
glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
if (status != GL_FRAMEBUFFER_COMPLETE)
{
LOGE("Incomplete frame buffer object!");
return false;
}
LOGI("Created FBO %d for texture %d.",
fb, tex);
}
return true;
}
to build the array of textures inside the setupGraphics function:
createTexture(tex, tw, th, 6);
for (int i = 0; i<25; i++) createTexture(aniTex[i], tw, th, 3+i);
SetupFramebuffer(tex, tw, th);
and finally to blit the framebuffer:
const GLenum attachment[1] = { GL_COLOR_ATTACHMENT0 };
void blitTexture() {
static int time = 0;
glBindFramebuffer(GL_FRAMEBUFFER, fb);
checkGlError("blitTexture glBindFramebuffer");
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1,
GL_TEXTURE_2D, aniTex[time], 0);
checkGlError("blitTexture glFramebufferTexture2D");
glReadBuffer(GL_COLOR_ATTACHMENT1);
checkGlError("blitTexture glReadBuffer");
glDrawBuffers(1, attachment);
checkGlError("blitTexture glDrawBuffers");
GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
if (status != GL_FRAMEBUFFER_COMPLETE) LOGE("Incomplete frame buffer object!");
glBlitFramebuffer(0,0,tw, th, 0, 0, tw, th, GL_COLOR_BUFFER_BIT, GL_LINEAR);
checkGlError("blitTexture glBlitFramebuffer");
int samples;
glGetFramebufferParameteriv(GL_READ_FRAMEBUFFER, GL_FRAMEBUFFER_DEFAULT_SAMPLES, &samples);
LOGI("SAMPLES draw buffer %d", samples);
time = ++time%25;
}
full project can be found here: https://github.com/AndrewBloom/BlitFramebufferExample

Android Opengl ES2, color instead of bitmap in texture

I need a 8x8x8 LED cube in an Android application. I found an OpenGl tutorial, which has this led cube, but it uses a bitmap on texture. Could I change it to a simple color? The texture helper is like this:
fun loadTexture(context: Context, resourceId: Int): Int {
val textureHandle = IntArray(1)
GLES20.glGenTextures(1, textureHandle, 0)
if (textureHandle[0] == 0) {
throw RuntimeException("Error generating texture name.")
}
val options = BitmapFactory.Options()
options.inScaled = false // No pre-scaling
// Read in the resource
val bitmap = BitmapFactory.decodeResource(context.resources, resourceId, options)
// Bind to the texture in OpenGL
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureHandle[0])
// Set filtering
GLES20.glTexParameteri(
GLES20.GL_TEXTURE_2D,
GLES20.GL_TEXTURE_MIN_FILTER,
GLES20.GL_NEAREST
)
GLES20.glTexParameteri(
GLES20.GL_TEXTURE_2D,
GLES20.GL_TEXTURE_MAG_FILTER,
GLES20.GL_NEAREST
)
// Load the bitmap into the bound texture.
GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0)
// Recycle the bitmap, since its data has been loaded into OpenGL.
bitmap.recycle()
return textureHandle[0]
}

fun loadTexture() {
val textureId = IntArray(1)
val color = byteArrayOf(0, 0, 127)
val bufferColor = ByteBuffer.allocateDirect(3)
bufferColor.put(color).position(0)
GLES20.glGenTextures(1, textureId, 0)
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId[0])
GLES20.glTexImage2D(GLES30.GL_TEXTURE_2D, 0,
GLES20.GL_RGB, 1, 1, 0, GLES30.GL_RGB,
GLES20.GL_UNSIGNED_BYTE, bufferColor)
return textureId[0]
}

glTranslatef/2D viewport setup issue

When i try glTranslatef(1,-1,0); it pushes my quad's lefthand corner to the center of the screen instead of what im trying to do, moving it 1 pixel to the left and 1 down. Im pretty sure this is because my viewport isnt set correctly but im unsure why. pic, view setup code and drawing code below.
setupView:
-(void)setupView:(GLView*)view
{
printf("setup view");
glClearColor(0,1,1, 1);
// Enable Smooth Shading, default not really needed.
glShadeModel(GL_SMOOTH);
// Depth buffer setup.
glClearDepthf(1.0f);
//enable textures.
glEnable(GL_TEXTURE_2D);
glHint(GL_PERSPECTIVE_CORRECTION_HINT,GL_FASTEST);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
CGRect rect = view.bounds;
glOrthof( 0,rect.size.width,-rect.size.height, 0, -1, 1 ) ;
glViewport(0, 0,rect.size.width,rect.size.height);
glMatrixMode(GL_PROJECTION);
// Bind the number of textures we need, in this case one.
glGenTextures(1, &texture[0]);
glBindTexture(GL_TEXTURE_2D, texture[0]);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_GENERATE_MIPMAP,GL_TRUE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glLoadIdentity();
NSString *path = [[NSBundle mainBundle] pathForResource:#"cm2" ofType:#"jpg"];
NSData *texData = [[NSData alloc] initWithContentsOfFile:path];
UIImage *image = [[UIImage alloc] initWithData:texData];
if (image == nil)
NSLog(#"Do real error checking here");
GLuint width = CGImageGetWidth(image.CGImage);
GLuint height = CGImageGetHeight(image.CGImage);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
void *imageData = malloc( height * width * 4 );
CGContextRef context = CGBitmapContextCreate( imageData, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big );
// Flip the Y-axis
CGContextTranslateCTM (context, 0, height);
CGContextScaleCTM (context, 1.0, -1.0);
CGColorSpaceRelease( colorSpace );
CGContextClearRect( context, CGRectMake( 0, 0, width, height ) );
CGContextDrawImage( context, CGRectMake( 0, 0, width, height ), image.CGImage );
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageData);
CGContextRelease(context);
free(imageData);
[image release];
[texData release];
}
drawView:
- (void)drawView:(GLView*)view
{
//draw calls
glColor4f(1,1,1,1);
glClear(GL_COLOR_BUFFER_BIT);
glLoadIdentity();
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
static const Vertex3D vertices[] = {
{0, 0, 1}, //TL
{ 1024.0f,0, 1}, //TR
{0, -1024.0f, 1}, //BL
{ 1024.0f, -1024.0f, 1} //BR
};
static const GLfloat texCoords[] = {
0.0, 1.0,
1.0, 1.0,
0.0, 0.0,
1.0, 0.0
};
glTranslatef(1,-1, 1);
glScalef(scale,scale,1);
glBindTexture(GL_TEXTURE_2D, texture[0]);
glVertexPointer(3, GL_FLOAT, 0, vertices);
glTexCoordPointer(2, GL_FLOAT, 0, texCoords);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
}

You need to first set up your viewport, then set the matrix mode to projection, then call glOrtho, like so:
glViewPort (0, 0, width, height);
glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
glOrtho (0, width, 0, height, -1, 1); // Usually this is -width/2,width/2,-height/2,height/2
Also, you probably want to set the matrix mode to ModelView after that to draw your model.