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nirali
05-18-2015, 05:52 AM
I am using opengl & using example of GLPaint. I have created app which apply twirl on image(texture) when user touch on image. I have issue that I need to save first touch and then apply next phase and so on. But on next touch the previous applied effect get removed.
I have tried to use depthbuffer & framebuffer both, but not able to get desired result. I am attaching all my code and shaders:

#import <QuartzCore/QuartzCore.h>
#import <OpenGLES/EAGLDrawable.h>
#import <GLKit/GLKit.h>

#import "PaintingView.h"

enum {
ATTRIB_VERTEX,
NUM_ATTRIBS
};

@interface PaintingView()
{
// The pixel dimensions of the backbuffer
GLint backingWidth;
GLint backingHeight;

EAGLContext *context;

// OpenGL names for the renderbuffer and framebuffers used to render to this view
GLuint viewRenderbuffer, viewFramebuffer, texture;

// OpenGL name for the depth buffer that is attached to viewFramebuffer, if it exists (0 if it does not exist)
GLuint depthRenderbuffer;


Boolean needsErase;

// Shader objects
// GLuint vertexShader;
// GLuint fragmentShader;
// GLuint shaderProgram;

// Buffer Objects
GLuint vboId;

BOOL initialized;

GLint inputImageTexture2Uniform, filterPositionAttribute, filterTextureCoordinateAttribute;

NSString *vertexShader, *fragmentShader;

Boolean firstTouch;

CGPoint twirlCenter;
}

// Program Handle
@property (assign, nonatomic, readonly) GLuint program;

// Attribute Handles
@property (assign, nonatomic, readonly) GLuint aPosition;

@property(nonatomic, readwrite) CGPoint location;
@property(nonatomic, readwrite) CGPoint previousLocation;


@end

@implementation PaintingView

// Implement this to override the default layer class (which is [CALayer class]).
// We do this so that our view will be backed by a layer that is capable of OpenGL ES rendering.
+ (Class)layerClass
{
return [CAEAGLLayer class];
}

// The GL view is stored in the nib file. When it's unarchived it's sent -initWithCoder:
- (id)initWithCoder:(NSCoder*)coder {
if ((self = [super initWithCoder:coder])) {
CAEAGLLayer *eaglLayer = (CAEAGLLayer *)self.layer;

eaglLayer.opaque = NO;
// In this application, we want to retain the EAGLDrawable contents after a call to presentRenderbuffer.
eaglLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], kEAGLDrawablePropertyRetainedBacking, kEAGLColorFormatRGBA8, kEAGLDrawablePropertyColorFormat, nil];

context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];

// context = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];

if (!context || ![EAGLContext setCurrentContext:context]) {
return nil;
}

// Set the view's scale factor as you wish
self.contentScaleFactor = [[UIScreen mainScreen] scale];

// Make sure to start with a cleared buffer
needsErase = YES;
}
return self;
}

// If our view is resized, we'll be asked to layout subviews.
// This is the perfect opportunity to also update the framebuffer so that it is
// the same size as our display area.
-(void)layoutSubviews
{
[EAGLContext setCurrentContext:context];

if (!initialized) {
initialized = [self initGL];
}
else {
[self resizeFromLayer:(CAEAGLLayer*)self.layer];
}
}

- (BOOL)initGL
{
// Generate IDs for a framebuffer object and a color renderbuffer
glGenFramebuffers(1, &viewFramebuffer);
glGenRenderbuffers(1, &viewRenderbuffer);

glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer);
glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);
// This call associates the storage for the current render buffer with the EAGLDrawable (our CAEAGLLayer)
// allowing us to draw into a buffer that will later be rendered to screen wherever the layer is (which corresponds with our view).
[context renderbufferStorage:GL_RENDERBUFFER fromDrawable:(id<EAGLDrawable>)self.layer];
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, viewRenderbuffer);

glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &backingWidth);
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &backingHeight);

// For this sample, we do not need a depth buffer. If you do, this is how you can create one and attach it to the framebuffer:
// glGenRenderbuffers(1, &depthRenderbuffer);
// glBindRenderbuffer(GL_RENDERBUFFER, depthRenderbuffer);
// glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, backingWidth, backingHeight);
// glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthRenderbuffer);

if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
{
NSLog(@"failed to make complete framebuffer object %x", glCheckFramebufferStatus(GL_FRAMEBUFFER));
return NO;
}

// Setup the view port in Pixels
glViewport(0, 0, backingWidth, backingHeight);

// Create a Vertex Buffer Object to hold our data
glGenBuffers(1, &vboId);

// Load the brush texture
// brushTexture = [self textureFromName:@"transprnt.png"];

// Load shaders
[self setupShaders];

inputImageTexture2Uniform = [self uniformIndex:@"inputImageTexture"];
UIImage *uyet = [UIImage imageNamed:@"kerala.jpg"];
[self setImage:uyet];




// Enable blending and set a blending function appropriate for premultiplied alpha pixel data
glEnable(GL_BLEND);
glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);


return YES;
}

- (void)setupShaders
{
vertexShader = @"RWTBase";
fragmentShader = @"TwirlShader";
// Program
_program = [self programWithVertexShader:vertexShader fragmentShader:fragmentShader];

// Attributes
filterPositionAttribute = glGetAttribLocation(_program, "aPosition");
filterTextureCoordinateAttribute = glGetAttribLocation(_program, "inputTextureCoordinate");

glEnableVertexAttribArray(filterPositionAttribute) ;
glEnableVertexAttribArray(filterTextureCoordinateA ttribute);

glBindAttribLocation(_program,
filterPositionAttribute,
[@"aPosition" UTF8String]);
glBindAttribLocation(_program,
filterTextureCoordinateAttribute,
[@"inputTextureCoordinate" UTF8String]);



// Program
glUseProgram(_program);

static const GLfloat textureCoordinates[] = {
0.0f, 0.0f,
1.0f, 0.0f,
0.0f, 1.0f,
1.0f, 1.0f,
};
static const GLfloat vertices[] = {
-1.0f, -1.0f,
1.0f, -1.0f,
-1.0f, 1.0f,
1.0f, 1.0f,
};

glVertexAttribPointer(filterPositionAttribute, 2, GL_FLOAT, 0, 0, vertices);
glVertexAttribPointer(filterTextureCoordinateAttri bute, 2, GL_FLOAT, 0, 0, textureCoordinates);

}

- (BOOL)resizeFromLayer:(CAEAGLLayer *)layer
{
// Allocate color buffer backing based on the current layer size
glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);
[context renderbufferStorage:GL_RENDERBUFFER fromDrawable:layer];
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &backingWidth);
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &backingHeight);

// For this sample, we do not need a depth buffer. If you do, this is how you can allocate depth buffer backing:
// glBindRenderbuffer(GL_RENDERBUFFER, depthRenderbuffer);
// glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, backingWidth, backingHeight);
// glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthRenderbuffer);

if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
{
NSLog(@"Failed to make complete framebuffer objectz %x", glCheckFramebufferStatus(GL_FRAMEBUFFER));
return NO;
}


// Update viewport
glViewport(0, 0, backingWidth, backingHeight);

return YES;
}

// Releases resources when they are not longer needed.
- (void)dealloc
{
// Destroy framebuffers and renderbuffers
if (viewFramebuffer) {
glDeleteFramebuffers(1, &viewFramebuffer);
viewFramebuffer = 0;
}
if (viewRenderbuffer) {
glDeleteRenderbuffers(1, &viewRenderbuffer);
viewRenderbuffer = 0;
}
if (depthRenderbuffer)
{
glDeleteRenderbuffers(1, &depthRenderbuffer);
depthRenderbuffer = 0;
}
// vbo
if (vboId) {
glDeleteBuffers(1, &vboId);
vboId = 0;
}

// tear down context
if ([EAGLContext currentContext] == context)
[EAGLContext setCurrentContext:nil];
}

// Custom Methods....
/*
***********
* *
* ATG *
* *
***********
*/
#pragma mark - Compile & Link
- (GLuint)programWithVertexShader:(NSString*)vsh fragmentShader:(NSString*)fsh {
// Build shaders
GLuint vertexShader1 = [self shaderWithName:vsh type:GL_VERTEX_SHADER];
GLuint fragmentShader1 = [self shaderWithName:fsh type:GL_FRAGMENT_SHADER];

// Create program
GLuint programHandle = glCreateProgram();

// Attach shaders
glAttachShader(programHandle, vertexShader1);
glAttachShader(programHandle, fragmentShader1);

// Link program
glLinkProgram(programHandle);

// Check for errors
GLint linkSuccess;
glGetProgramiv(programHandle, GL_LINK_STATUS, &linkSuccess);
if (linkSuccess == GL_FALSE) {
GLchar messages[1024];
glGetProgramInfoLog(programHandle, sizeof(messages), 0, &messages[0]);
NSLog(@"%@:- GLSL Program Error: %s", [self class], messages);
}

// Delete shaders
glDeleteShader(vertexShader1);
glDeleteShader(fragmentShader1);

return programHandle;
}

- (GLuint)shaderWithName:(NSString*)name type:(GLenum)type {
// Load the shader file
NSString* file;
if (type == GL_VERTEX_SHADER) {
file = [[NSBundle mainBundle] pathForResource:name ofType:@"vsh"];
} else if (type == GL_FRAGMENT_SHADER) {
file = [[NSBundle mainBundle] pathForResource:name ofType:@"fsh"];
}

// Create the shader source
const GLchar* source = (GLchar*)[[NSString stringWithContentsOfFile:file encoding:NSUTF8StringEncoding error:nil] UTF8String];

// Create the shader object
GLuint shaderHandle = glCreateShader(type);

// Load the shader source
glShaderSource(shaderHandle, 1, &source, 0);

// Compile the shader
glCompileShader(shaderHandle);

// Check for errors
GLint compileSuccess;
glGetShaderiv(shaderHandle, GL_COMPILE_STATUS, &compileSuccess);
if (compileSuccess == GL_FALSE) {
GLchar messages[1024];
glGetShaderInfoLog(shaderHandle, sizeof(messages), 0, &messages[0]);
NSLog(@"%@:- GLSL Shader Error: %s", [self class], messages);
}

return shaderHandle;
}

// Touch Methiods..
#pragma mark - Touches

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

// CGRect bounds = [self.view bounds];
// UITouch* touch = [[event touchesForView:self.view] anyObject];
// // NSLog(@"Hellossss");
// firstTouch = YES;
// _location = [touch locationInView:self.view];
// _location.y = bounds.size.height - _location.y;
}

// Handles the continuation of a touch.
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{

CGRect bounds = [self bounds];
UITouch* touch = [[event touchesForView:self] anyObject];


UITouch* touchEvent = [touches anyObject];
CGPoint locationInView = [touchEvent locationInView:self];
twirlCenter = getNormalizedPoint(self, locationInView);


// [EAGLContext setCurrentContext:context];
// glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer);

// Render the stroke
[self applyEffect];

// [self drawEffects];
if (firstTouch) {
firstTouch = NO;
_previousLocation = [touch previousLocationInView:self];
_previousLocation.y = bounds.size.height - _previousLocation.y;
} else {
_location = [touch locationInView:self];
_location.y = bounds.size.height - _location.y;
_previousLocation = [touch previousLocationInView:self];
_previousLocation.y = bounds.size.height - _previousLocation.y;
}

// Render the stroke
[self renderLineFromPoint:_previousLocation toPoint:_location];
}

-(void)drawEffects {
// [EAGLContext setCurrentContext:context];
// glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer);

// Draw
glBindBuffer(GL_ARRAY_BUFFER, vboId);

glUseProgram(_program);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);


// Display the buffer
glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);
[context presentRenderbuffer:GL_RENDERBUFFER];
}

-(void)applyEffect {

// [EAGLContext setCurrentContext:context];
// glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer);

GLint radiusIndex = [self uniformIndex:@"radius"];
glUniform1f(radiusIndex, 0.1);

GLint angleIndex = [self uniformIndex:@"angle"];
glUniform1f(angleIndex, -0.5);

// twirlCenter = CGPointMake(1.0, 0.0);
GLint centerIndex = [self uniformIndex:@"center"];

GLfloat positionArray[2];
positionArray[0] = twirlCenter.x;
positionArray[1] = twirlCenter.y;
glUniform2fv(centerIndex, 1, positionArray);

}

// Drawings a line onscreen based on where the user touches
- (void)renderLineFromPoint:(CGPoint)start toPoint:(CGPoint)end
{
static GLfloat* vertexBuffer = NULL;
static NSUInteger vertexMax = 64;
NSUInteger vertexCount = 0,
count,
i;

[EAGLContext setCurrentContext:context];
glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer);

// Convert locations from Points to Pixels
CGFloat scale = self.contentScaleFactor;
start.x *= scale;
start.y *= scale;
end.x *= scale;
end.y *= scale;

// Allocate vertex array buffer
if(vertexBuffer == NULL)
vertexBuffer = malloc(vertexMax * 2 * sizeof(GLfloat));

// Add points to the buffer so there are drawing points every X pixels
count = MAX(ceilf(sqrtf((end.x - start.x) * (end.x - start.x) + (end.y - start.y) * (end.y - start.y)) / 3), 1);
for(i = 0; i < count; ++i) {
if(vertexCount == vertexMax) {
vertexMax = 2 * vertexMax;
vertexBuffer = realloc(vertexBuffer, vertexMax * 2 * sizeof(GLfloat));
}

vertexBuffer[2 * vertexCount + 0] = start.x + (end.x - start.x) * ((GLfloat)i / (GLfloat)count);
vertexBuffer[2 * vertexCount + 1] = start.y + (end.y - start.y) * ((GLfloat)i / (GLfloat)count);
vertexCount += 1;
}

// Load data to the Vertex Buffer Object
glBindBuffer(GL_ARRAY_BUFFER, vboId);
glBufferData(GL_ARRAY_BUFFER, vertexCount*2*sizeof(GLfloat), vertexBuffer, GL_DYNAMIC_DRAW);

glEnableVertexAttribArray(ATTRIB_VERTEX);
glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, GL_FALSE, 0, 0);

// Draw
glBindTexture(GL_TEXTURE_2D, texture);

glUseProgram(_program);


glDrawArrays(GL_POINTS, 0, (int)vertexCount);

// Display the buffer
glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);
[context presentRenderbuffer:GL_RENDERBUFFER];
}

///fsdffdf


static CGPoint getNormalizedPoint(UIView* view, CGPoint locationInView)
{
const float normalizedX = (locationInView.x / view.bounds.size.width) * (2.f - 1.f);
const float normalizedY = ((view.bounds.size.height - locationInView.y) / view.bounds.size.height) * (2.f - 1.f);

return CGPointMake(normalizedX, normalizedY);
}

// set Img...

- (void)setImage:(UIImage *)image
{
// Create an RGBA bitmap context
CGImageRef CGImage = image.CGImage;
GLint width = (GLint)CGImageGetWidth(CGImage);
GLint height = (GLint)CGImageGetHeight(CGImage);
size_t bitsPerComponent = 8;
size_t bytesPerRow = width * 4;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context1 = CGBitmapContextCreate(NULL, width, height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedFirst|kCGBitmapByteOrder 32Little);
// Invert vertically for OpenGL
CGContextTranslateCTM(context1, 0, height);
CGContextScaleCTM(context1, 1, -1);
CGContextDrawImage(context1, CGRectMake(0, 0, width, height), CGImage);
GLubyte *textureData = (GLubyte *)CGBitmapContextGetData(context1);

// [self setContentSize:CGSizeMake(width, height)];
// [self _setTextureData:textureData width:width height:height];
[self generateDefaultTextureWithWidth:width height:height data:textureData];

CGContextRelease(context1);
CGColorSpaceRelease(colorSpace);
}

- (GLuint)generateDefaultTextureWithWidth:(GLint)wid th height:(GLint)height data:(GLvoid *)data
{
// texture = 0;
glActiveTexture(GL_TEXTURE0);
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glUniform1i(inputImageTexture2Uniform, 0);


// glGenTextures(1, &texture);
// glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_BGRA, GL_UNSIGNED_BYTE, data);
// glBindTexture(GL_TEXTURE_2D, 0);
return texture;
}

- (GLuint)uniformIndex:(NSString *)uniformName
{
return glGetUniformLocation(_program, [uniformName UTF8String]);
}

- (void)setPaintLine12
{
[self performSelector:@selector(drawEffects) withObject:nil afterDelay:0.5];
}

// Erases the screen
- (void)erase
{
NSLog(@"erase");
}

- (BOOL)canBecomeFirstResponder {
return YES;
}

@end

Also attaching shader as follows:

precision highp float;

varying vec2 textureCoordinate;

uniform sampler2D inputImageTexture;

uniform vec2 center;
uniform float radius;
uniform float angle;

void main()
{
vec2 textureCoordinateToUse = textureCoordinate;
float dist = distance(center, textureCoordinate);
if (dist < radius)
{
textureCoordinateToUse -= center;
float percent = (radius - dist) / radius;
float theta = percent * percent * angle * 8.0;
float s = sin(theta);
float c = cos(theta);
textureCoordinateToUse = vec2(dot(textureCoordinateToUse, vec2(c, -s)), dot(textureCoordinateToUse, vec2(s, c)));
textureCoordinateToUse += center;
}

gl_FragColor = texture2D(inputImageTexture, textureCoordinateToUse );
}


Please help me to debug what is wrong and how to resolve this.
You can also run complete project from here Twirl on Touch-github (https://github.com/niralipandey/Twirl-on-touch)