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  • iPhone Rendering Question

    - by slythic
    Hi all, I'm new to iPhone/Objective-C development. I "jumped the gun" and started reading and implementing some chapters from O'Reilly's iPhone Development. I was following the ebook's code exactly and my code was generating the following error: CGContextSetFillColorWithColor: invalid context CGContextFillRects: invalid context CGContextSetFillColorWithColor: invalid context CGContextGetShouldSmoothFonts: invalid context However, when I downloaded the sample code for the same chapter the code is different. Book Code: - (void) Render { CGContextRef g = UIGraphicsGetCurrentContext(); //fill background with gray CGContextSetFillColorWithColor(g, [UIColor grayColor].CGColor); CGContextFillRect(g, CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)); //draw text in black. CGContextSetFillColorWithColor(g, [UIColor blackColor].CGColor); [@"O'Reilly Rules!" drawAtPoint:CGPointMake(10.0, 20.0) withFont:[UIFont systemFontOfSize:[UIFont systemFontSize]]]; } Actual Project Code from the website (works): - (void) Render { [self setNeedsDisplay]; //this sets up a deferred call to drawRect. } - (void)drawRect:(CGRect)rect { CGContextRef g = UIGraphicsGetCurrentContext(); //fill background with gray CGContextSetFillColorWithColor(g, [UIColor grayColor].CGColor); CGContextFillRect(g, CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)); //draw text in black. CGContextSetFillColorWithColor(g, [UIColor blackColor].CGColor); [@"O'Reilly Rules!" drawAtPoint:CGPointMake(10.0, 20.0) withFont:[UIFont systemFontOfSize:[UIFont systemFontSize]]]; } What is it about these lines of code that make the app render correctly? - (void) Render { [self setNeedsDisplay]; //this sets up a deferred call to drawRect. } - (void)drawRect:(CGRect)rect { Thanks in advance for helping out a newbie!

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  • Can't block capslock with CGEventTap

    - by Thor Frølich
    I'm using Quartz CGEventTap in an attempt to globally intercept capslock presses and block them (to have them do something useful instead). I succesfully detect capslock presses but have so far been unable to block them. My code (originating from this stackoverflow answer) is something like this: eventTap = CGEventTapCreate(kCGHIDEventTap, kCGTailAppendEventTap, kCGEventTapOptionDefault, eventMask, myCGEventCallback, &oldFlags); runLoopSource = CFMachPortCreateRunLoopSource(kCFAllocatorDefault, eventTap, 0); CFRunLoopAddSource(CFRunLoopGetCurrent(), runLoopSource, kCFRunLoopCommonModes); CGEventTapEnable(eventTap, true); CGEventRef myCGEventCallback(CGEventTapProxy proxy, CGEventType type, CGEventRef theEvent, void *refcon) { CGEventFlags *oldFlags = (CGEventFlags *)refcon; switch (type) { case kCGEventFlagsChanged: { CGEventFlags newFlags = CGEventGetFlags(theEvent); CGEventFlags changedFlags = *oldFlags ^ newFlags; *oldFlags = newFlags; if (changedFlags == 65536) { NSLog(@"Capslock pressed. Let's not return the event"); return NULL; } break; } default: break; } NSLog(@"Different modifier than capslock. Returning the event"); return theEvent; } If I understand correctly returning NULL should effectively block the keypress from propagating. Indeed it also does for "normal" keyup and -down events. However capslock toggles regardless. Any ideas why that is? Am I making incorrect assumptions? And/or how can I do things differently to achieve my goal? Thanks, Thor

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  • Custom UILabel does not show text.

    - by Oscar
    Hi! I've made an custom UILabel class in which i draw a red line at the bottom of the frame. The red line is showing but i cant get the text to show. #import <UIKit/UIKit.h> @interface LetterLabel : UILabel { } @end #import "LetterLabel.h" @implementation LetterLabel - (id)initWithFrame:(CGRect)frame { if (self = [super initWithFrame:frame]) { // Initialization code } return self; } - (void)drawRect:(CGRect)rect { CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 2.0); CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0); CGContextBeginPath(UIGraphicsGetCurrentContext()); CGContextMoveToPoint(UIGraphicsGetCurrentContext(), 0.0, self.frame.size.height); CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), self.frame.size.width, self.frame.size.height); CGContextStrokePath(UIGraphicsGetCurrentContext()); } - (void)dealloc { [super dealloc]; } @end #import <UIKit/UIKit.h> #import "Word.h" @interface WordView : UIView { Word *gameWord; } @property (nonatomic, retain) Word *gameWord; @end @implementation WordView @synthesize gameWord; - (id)initWithFrame:(CGRect)frame { if (self = [super initWithFrame:frame]) { self.backgroundColor = [UIColor whiteColor]; LetterLabel *label = [[LetterLabel alloc] initWithFrame:CGRectMake(0, 0, 20, 30)]; label.backgroundColor = [UIColor cyanColor]; label.textAlignment = UITextAlignmentCenter; label.textColor = [UIColor blackColor]; [label setText:@"t"]; [self addSubview:label]; } return self; } - (void)drawRect:(CGRect)rect { // Drawing code } - (void)dealloc { [gameWord release]; [super dealloc]; } @end

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  • draw ios quartz 2d path with a varying alpha component

    - by Giovanni
    Hi, I'd like to paint some Bezier curves with the alpha channel that is changing during the curve painting. Right now I'm able to draw bezier paths, with a fixed alpha channel. What I'd like to do is to draw a single bezier curve that uses a certain value of the alpha channel for the first n points of the path another, alpha value for the subsequent m points and so on. The code I'm using for drawing bezier path is: CGContextSetStrokeColorWithColor(context, curva.color.CGColor); .... CGContextAddCurveToPoint(context, cp1.x, cp1.y, cp2.x, cp2.y, endPoint.x, endPoint.y); .... CGContextStrokePath(context); Is there a way to achieve what I'm describing? Many thanks, Giovanni

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  • masking a UIImage

    - by iworkinprogress
    I'm working on an app that can change the borders or a rectangular UIImage. The borders will vary, but will look like the UIImage was cut out with scissors, or something to that affect. What is the best way to do this? My first thought is to prep a bunch of transparent PNGs with the correct border effect I'm looking for, and then somehow use that as a mask for my UIImage. Is this the right path? Or is there a more flexible programmatic way to do this?

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  • iPhone: How to Maintain Original Image Size Thoughout Image Edits

    - by maddy
    hi, I am developing an iPhone app that resizes and merges images. I want to select two photos of size 1600x1200 from photo library and then merge both into a single image and save that new image back to the photo library. However, I can't get the right size for the merged image. I take two image views of frame 320x480 and set the view's image to my imported images. After manipulating the images (zooming, cropping, rotating), I then save the image to album. When I check the image size it shows 600x800. How do I get the original size of 1600*1200? I've been stuck on this problem from two weeks! Thanks in advance.

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  • Matlab: Adding symbols to figure

    - by niko
    Hi, Below is the user interface I have created to simulate LDPC coding and decoding The code sequence is decoded iteratively by passing values between the left and right nodes through the connections. The first thing it would be good to add in order to improve visualization is to add arrows to the connections in the direction of passing values. The alternative is to draw a bigger arrow at the top of the connection showing the direction. Another thing I would like to do is displaying the current mathematical operation below the connection (in this example c * H'). What I don't know how to do is displaying special characters and mathematical symbols and other kinds of text such as subscript and superscript in the figure (for example sum sign and subscript "T" instead of sign ="'" to indicate transposed matrix). I would be very thankful if anyone could point to any useful resources for the questions above or show the solution. Thank you.

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  • How do I use texture-mapping in a simple ray tracer?

    - by fastrack20
    I am attempting to add features to a ray tracer in C++. Namely, I am trying to add texture mapping to the spheres. For simplicity, I am using an array to store the texture data. I obtained the texture data by using a hex editor and copying the correct byte values into an array in my code. This was just for my testing purposes. When the values of this array correspond to an image that is simply red, it appears to work close to what is expected except there is no shading. The bottom right of the image shows what a correct sphere should look like. This sphere's colour using one set colour, not a texture map. Another problem is that when the texture map is of something other than just one colour pixels, it turns white. My test image is a picture of water, and when it maps, it shows only one ring of bluish pixels surrounding the white colour. When this is done, it simply appears as this: Here are a few code snippets: Color getColor(const Object *object,const Ray *ray, float *t) { if (object->materialType == TEXTDIF || object->materialType == TEXTMATTE) { float distance = *t; Point pnt = ray->origin + ray->direction * distance; Point oc = object->center; Vector ve = Point(oc.x,oc.y,oc.z+1) - oc; Normalize(&ve); Vector vn = Point(oc.x,oc.y+1,oc.z) - oc; Normalize(&vn); Vector vp = pnt - oc; Normalize(&vp); double phi = acos(-vn.dot(vp)); float v = phi / M_PI; float u; float num1 = (float)acos(vp.dot(ve)); float num = (num1 /(float) sin(phi)); float theta = num /(float) (2 * M_PI); if (theta < 0 || theta == NAN) {theta = 0;} if (vn.cross(ve).dot(vp) > 0) { u = theta; } else { u = 1 - theta; } int x = (u * IMAGE_WIDTH) -1; int y = (v * IMAGE_WIDTH) -1; int p = (y * IMAGE_WIDTH + x)*3; return Color(TEXT_DATA[p+2],TEXT_DATA[p+1],TEXT_DATA[p]); } else { return object->color; } }; I call the colour code here in Trace: if (object->materialType == MATTE) return getColor(object, ray, &t); Ray shadowRay; int isInShadow = 0; shadowRay.origin.x = pHit.x + nHit.x * bias; shadowRay.origin.y = pHit.y + nHit.y * bias; shadowRay.origin.z = pHit.z + nHit.z * bias; shadowRay.direction = light->object->center - pHit; float len = shadowRay.direction.length(); Normalize(&shadowRay.direction); float LdotN = shadowRay.direction.dot(nHit); if (LdotN < 0) return 0; Color lightColor = light->object->color; for (int k = 0; k < numObjects; k++) { if (Intersect(objects[k], &shadowRay, &t) && !objects[k]->isLight) { if (objects[k]->materialType == GLASS) lightColor *= getColor(objects[k], &shadowRay, &t); // attenuate light color by glass color else isInShadow = 1; break; } } lightColor *= 1.f/(len*len); return (isInShadow) ? 0 : getColor(object, &shadowRay, &t) * lightColor * LdotN; } I left out the rest of the code as to not bog down the post, but it can be seen here. Any help is greatly appreciated. The only portion not included in the code, is where I define the texture data, which as I said, is simply taken straight from a bitmap file of the above image. Thanks.

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  • ID3D10Device Memory Allocation Strategy and E_OUTOFMEMORY

    - by Buzz
    Hi,guys, I want to know more detail of memory allocation strategy in D3D10Device. Could you give me some help? First questions is: I know D3D10 has done some work on memory virtualization that means client don't need to consider where the buffer was reserved, GPU memory, AGP memory or Process system memory. Is this correct? Second question is: When I use ID3D10Device to CreateBuffer continuously, no matter what buffer desc type is, for example ID3D10Device::CreateBuffer( ... D3D10_USAGE_DEFAULT ... ); ID3D10Device::CreateBuffer( ... D3D10_USAGE_IMMUTABLE ... ); ID3D10Device::CreateBuffer( ... D3D10_USAGE_DYNAMIC ... ); ID3D10Device::CreateBuffer( ... D3D10_USAGE_STAGING ... ); etc, if CreateBuffer return error code "E_OUTOFMEMORY", does that mean process virtual memory is exhausted? And at this time, memory allocation on process default heap would also be failed? Thanks in advance!

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  • How to- NSAttributedString to CGImageRef

    - by kroko
    Hello! I'm writing a QuickLook plugin. Well, everything works. Just want to try it make better ;). Thus the question. Here is a function that returns thumbnail image and that I'm using now. QLThumbnailRequestSetImageWithData( QLThumbnailRequestRef thumbnail, CFDataRef data, CFDictionaryRef properties); ); http://developer.apple.com/mac/library/documentation/UserExperience/Reference/QLThumbnailRequest_Ref/Reference/reference.html#//apple_ref/c/func/QLThumbnailRequestSetImageWithData Right now I'm creating a TIFF - encapsulated it into NSData. An example // Setting CFDataRef CGSize thumbnailMaxSize = QLThumbnailRequestGetMaximumSize(thumbnail); NSMutableAttributedString *attributedString = [[[NSMutableAttributedString alloc] initWithString:@"dummy" attributes:[NSDictionary dictionaryWithObjectsAndKeys: [NSFont fontWithName:@"Monaco" size:10], NSFontAttributeName, [NSColor colorWithCalibratedRed:0.0 green:0.0 blue:0.0 alpha:1.0], NSForegroundColorAttributeName, nil] ] autorelease]; NSImage *thumbnailImage = [[[NSImage alloc] initWithSize:NSMakeSize(thumbnailMaxSize.width, thumbnailMaxSize.height)] autorelease]; [thumbnailImage lockFocus]; [[NSColor whiteColor] set]; NSRectFill(NSMakeRect(0, 0, thumbnailMaxSize.width, thumbnailMaxSize.height)); [attributedString drawInRect:NSMakeRect(0, 0, thumbnailMaxSize.width, thumbnailMaxSize.height)]; [thumbnailImage unlockFocus]; (CFDataRef)[thumbnailImage TIFFRepresentation]; // This is data // Setting CFDictionaryRef (CFDictionaryRef)[NSDictionary dictionaryWithObjectsAndKeys:@"kUTTypeTIFF", (NSString *)kCGImageSourceTypeIdentifierHint, nil ]; // this is properties However QuickLook provides another function to return thumbnail image, namely QLThumbnailRequestSetImage( QLThumbnailRequestRef thumbnail, CGImageRef image, CFDictionaryRef properties); ); http://developer.apple.com/mac/library/documentation/UserExperience/Reference/QLThumbnailRequest_Ref/Reference/reference.html#//apple_ref/c/func/QLThumbnailRequestSetImage I have a feeling that passing CGImage to the QL instead of TIFF data would help in speeding things up. However- I have never worked with CG context before. I know, the documentation is there :), but anyways- could anyone give an example how to turn that NSAttributed string into CGImageRef. An example is worth 10 times reading the documentation ;) Any help appreciated. Thanks in advance!

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  • Fast rectangle to rectangle intersection

    - by Jeremy Rudd
    What's a fast way to test if 2 rectangles are intersecting? A search on the internet came up with this one-liner (WOOT!), but I don't understand how to write it in Javascript, it seems to be written in an ancient form of C++. struct { LONG left; LONG top; LONG right; LONG bottom; } RECT; bool IntersectRect(const RECT * r1, const RECT * r2) { return ! ( r2->left > r1->right || r2->right left || r2->top > r1->bottom || r2->bottom top ); }

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  • iPhone+Quartz+OpenGL. What is the correct way for Quartz and OpenGL to play nice together regarding

    - by dugla
    So we know the CoreGraphics/Quartz imaging model is based on pre-multiplied alpha. We also know that OpenGL blending is based on un-premultiplied alpha. What is the best practice to avoid head explosion when doing blending with textures that are derived from pre-multiplied alpha imagery (PNG files generated in Photoshop with pre-multiplied alpha). Given the apples/oranges mish mash of Quartz and OpenGL, what is the correct glBlendFunc for doing the fundamental Porter/Duff "over" operation? Typical example: A simple paint program. Brush shapes are texture-map patterns created from pre-multiplied alpha rgba images. Paint color is specified via glColor4(...) with the alpha channel used to control paint transparency. GL_MODULATE is used so the brush texture multiplies the (translucent) paint color to blend the color into the canvas. Problem: The texture is premult. The color is not. What is the correct way to handle this fundamental inconsistency? Thanks, Doug

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  • How to structure class to support imported 3d model ?

    - by brainydexter
    Hello, I've written a C++ library that reads in this 3d model file (collada DAE). uptil now, I would output a list of triangles and handle each at rendering stage. But now, I need to attach some Bounding sphere information with the imported model. I need some advice on how should I organize this in code. Here are some specs of the 3D file format: - 3D model is represented as a Tree consisting of nodes - each node can contain other nodes, geometry information, transformation etc My requirements: - a bounding sphere associated with each node, thereby yielding a tree of bounding sphere hierarchy for the model itself. - actual vertex information What would be the recommended way to deal with this situation? Thanks

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  • Merge overlapping triangles into a polygon

    - by nornagon
    I've got a bunch of overlapping triangles from a 3D model projected into a 2D plane. I need to merge each island of touching triangles into a closed, non-convex polygon. The resultant polygons shouldn't have any holes in them (since the source data doesn't). Many of the source triangles share (floating point identical) edges with other triangles in the source data. What's the easiest way to do this? Performance isn't particularly important, since this will be done at design time.

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  • Unexplained crashs with coregraphic

    - by Ziggy
    Hello there, i'm on this bug for a week now, and i can't solve it. I have some crash with coregraphic calls, it happen randomly (sometimes after 2 mn, or just at the start), but often at the same places in the code. I have a class that just wrap a CGContext, it have a CGContextRef as member. This Object is re-created each time DrawRect() is called, so the CGContextRef is always up-to-date. The draw calls came from the main thread, only After looking for this kind of error, it appear that it should be object Release related. Here is an example of an error : #0 0x90d8a7a7 in ___forwarding___ #1 0x90d8a8b2 in __forwarding_prep_0___ #2 0x90d0d0b6 in CFRetain #3 0x95e54a5d in CGColorRetain #4 0x95e5491d in CGGStateCreateCopy #5 0x95e5486d in CGGStackSave #6 0x95e54846 in CGContextSaveGState #7 0x00073500 in CAutoContextState::CAutoContextState at Context.cpp:47 the AutoContextSave() class look like this : class CAutoContextState { private: CGContextRef m_Hdc; public: CAutoContextState(const CGContextRef& Hdc) { m_Hdc = Hdc; CGContextSaveGState(m_Hdc); } virtual ~CAutoContextState() { CGContextRestoreGState(m_Hdc); } }; It crash at CGContextSaveGState(m_Hdc). Here is what i see into GDB: * -[Not A Type retain]: message sent to deallocated instance 0x16a148b0. When i type malloc-history on the address, i have this : 0: 0x954cf10c in malloc_zone_malloc 1: 0x90d0d201 in _CFRuntimeCreateInstance 2: 0x95e3fe88 in CGTypeCreateInstanceWithAllocator 3: 0x95e44297 in CGTypeCreateInstance 4: 0x95e58f57 in CGColorCreate 5: 0x71fdd in _ZN4Flux4Draw8CContext10DrawStringERKNS_7CStringEPKNS0_5CFontEPKNS0_6CBrushERKNS_5CRectENS0_12tagAlignmentESE_NS0_17tagStringTrimmingEfiPKf at /Volumes/Sources Mac/Flux/Sources/DotFlux/Projects/../Draw/CoreGraphic/Context.cpp:1029 Which point me at this line of code : f32 components[] = {pSolidBrush->GetColor().GetfRed(), pSolidBrush->GetColor().GetfGreen(), pSolidBrush->GetColor().GetfBlue(), pSolidBrush->GetColor().GetfAlpha()}; //{ 1.0, 0.0, 0.0, 0.8 }; CGColorRef TextColor = CGColorCreate(rgbColorSpace, components); Point this func : CGColorCreate(); Any help would be appreciated, i need to finish this task very soon, but i don't know how to resolve this :( Thanks.

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  • Literature and Tutorials for Writing a Ray Tracer

    - by grrussel
    I am interested in finding recommendations on books on writing a raytracer, simple and clear implementations of ray tracing that can be seen on the web, and online resources on introductory raytracing. Ideally, the approach would be incremental and tutorial in style, and explain both the programming techniques and underyling mathematics, starting from the basics.

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  • Finding the intersection of two vector equations.

    - by Matthew Mitchell
    I've been trying to solve this and I found an equation that gives the possibility of zero division errors. Not the best thing: v1 = (a,b) v2 = (c,d) d1 = (e,f) d2 = (h,i) l1: v1 + ?d1 l2: v2 + µd2 Equation to find vector intersection of l1 and l2 programatically by re-arranging for lambda. (a,b) + ?(e,f) = (c,d) + µ(h,i) a + ?e = c + µh b +?f = d + µi µh = a + ?e - c µi = b +?f - d µ = (a + ?e - c)/h µ = (b +?f - d)/i (a + ?e - c)/h = (b +?f - d)/i a/h + ?e/h - c/h = b/i +?f/i - d/i ?e/h - ?f/i = (b/i - d/i) - (a/h - c/h) ?(e/h - f/i) = (b - d)/i - (a - c)/h ? = ((b - d)/i - (a - c)/h)/(e/h - f/i) Intersection vector = (a + ?e,b + ?f) Not sure if it would even work in some cases. I haven't tested it. I need to know how to do this for values as in that example a-i. Thank you.

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  • Convet from line points to shape points

    - by VOX
    I have an array of points that make up a line. However I need to draw the line with the width of n pixels. How can I transform that points for lines to points for polygon (or a shape) so I can directly draw it on canvas. I'm developing two program at the same time, one is j2me and another is .NET CF. j2me doesn't support drawing lines with width. Please take a look at the picture. link text

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  • How to draw a drop shadow AND gradient with quartz2d?

    - by Luke
    Hello! I've a custom shape drawing using coregraphics and i want to add a drop shadow and a gradient to it also. I've been trying and searching a lot of informations on how to combine and do this, but i can't get it to work. I'm able to draw only one either. Anyone doing this already or know how to do this? Thank you.

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  • Problem when trying to use simple Shaders + VBOs

    - by Mr.Gando
    Hello I'm trying to convert the following functions to a VBO based function for learning purposes, it displays a static texture on screen. I'm using OpenGL ES 2.0 with shaders on the iPhone (should be almost the same than regular OpenGL in this case), this is what I got working: //Works! - (void) drawAtPoint:(CGPoint)point depth:(CGFloat)depth { GLfloat coordinates[] = { 0, 1, 1, 1, 0, 0, 1, 0 }; GLfloat width = (GLfloat)_width * _maxS, height = (GLfloat)_height * _maxT; GLfloat vertices[] = { -width / 2 + point.x, -height / 2 + point.y, width / 2 + point.x, -height / 2 + point.y, -width / 2 + point.x, height / 2 + point.y, width / 2 + point.x, height / 2 + point.y, }; glBindTexture(GL_TEXTURE_2D, _name); //Attrib position and attrib_tex coord are handles for the shader attributes glVertexAttribPointer(ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices); glEnableVertexAttribArray(ATTRIB_POSITION); glVertexAttribPointer(ATTRIB_TEXCOORD, 2, GL_FLOAT, GL_FALSE, 0, coordinates); glEnableVertexAttribArray(ATTRIB_TEXCOORD); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); } I tried to do this to convert to a VBO however I don't see anything displaying on-screen with this version: //Doesn't display anything - (void) drawAtPoint:(CGPoint)point depth:(CGFloat)depth { GLfloat width = (GLfloat)_width * _maxS, height = (GLfloat)_height * _maxT; GLfloat position[] = { -width / 2 + point.x, -height / 2 + point.y, width / 2 + point.x, -height / 2 + point.y, -width / 2 + point.x, height / 2 + point.y, width / 2 + point.x, height / 2 + point.y, }; //Texture on-screen position ( each vertex is x,y in on-screen coords ) GLfloat coordinates[] = { 0, 1, 1, 1, 0, 0, 1, 0 }; // Texture coords from 0 to 1 glBindVertexArrayOES(vao); glGenVertexArraysOES(1, &vao); glGenBuffers(2, vbo); //Buffer 1 glBindBuffer(GL_ARRAY_BUFFER, vbo[0]); glBufferData(GL_ARRAY_BUFFER, 8 * sizeof(GLfloat), position, GL_STATIC_DRAW); glEnableVertexAttribArray(ATTRIB_POSITION); glVertexAttribPointer(ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, 0, position); //Buffer 2 glBindBuffer(GL_ARRAY_BUFFER, vbo[1]); glBufferData(GL_ARRAY_BUFFER, 8 * sizeof(GLfloat), coordinates, GL_DYNAMIC_DRAW); glEnableVertexAttribArray(ATTRIB_TEXCOORD); glVertexAttribPointer(ATTRIB_TEXCOORD, 2, GL_FLOAT, GL_FALSE, 0, coordinates); //Draw glBindVertexArrayOES(vao); glBindTexture(GL_TEXTURE_2D, _name); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); } In both cases I'm using this simple Vertex Shader //Vertex Shader attribute vec2 position;//Bound to ATTRIB_POSITION attribute vec4 color; attribute vec2 texcoord;//Bound to ATTRIB_TEXCOORD varying vec2 texcoordVarying; uniform mat4 mvp; void main() { //You CAN'T use transpose before in glUniformMatrix4fv so... here it goes. gl_Position = mvp * vec4(position.x, position.y, 0.0, 1.0); texcoordVarying = texcoord; } The gl_Position is equal to product of mvp * vec4 because I'm simulating glOrthof in 2D with that mvp And this Fragment Shader //Fragment Shader uniform sampler2D sampler; varying mediump vec2 texcoordVarying; void main() { gl_FragColor = texture2D(sampler, texcoordVarying); } I really need help with this, maybe my shaders are wrong for the second case ? thanks in advance.

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  • Automatic tracking algorithm

    - by nico
    Hi everyone, I'm trying to write a simple tracking routine to track some points on a movie. Essentially I have a series of 100-frames-long movies, showing some bright spots on dark background. I have ~100-150 spots per frame, and they move over the course of the movie. I would like to track them, so I'm looking for some efficient (but possibly not overkilling to implement) routine to do that. A few more infos: the spots are a few (es. 5x5) pixels in size the movement are not big. A spot generally does not move more than 5-10 pixels from its original position. The movements are generally smooth. the "shape" of these spots is generally fixed, they don't grow or shrink BUT they become less bright as the movie progresses. the spots don't move in a particular direction. They can move right and then left and then right again the user will select a region around each spot and then this region will be tracked, so I do not need to automatically find the points. As the videos are b/w, I though I should rely on brigthness. For instance I thought I could move around the region and calculate the correlation of the region's area in the previous frame with that in the various positions in the next frame. I understand that this is a quite naïve solution, but do you think it may work? Does anyone know specific algorithms that do this? It doesn't need to be superfast, as long as it is accurate I'm happy. Thank you nico

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  • What's a good matrix manipulation library available for C ?

    - by banister
    Hi, I am doing a lot of image processing in C and I need a good, reasonably lightweight, and above all FAST matrix manipulation library. I am mostly focussing on affine transformations and matrix inversions, so i do not need anything too sophisticated or bloated. Primarily I would like something that is very fast (using SSE perhaps?), with a clean API and (hopefully) prepackaged by many of the unix package management systems. Note this is for C not for C++. Thanks :)

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  • rotate a plane around a diagonal

    - by compie
    I would like to rotate a plane, not around a single (X or Y) axis, but around the diagonal (45 degrees between X and Y). How do I calculate the Rx and Ry given the Rdiagonal? (Rdiagonal is the amount of rotation I would like to achieve around the diagonal axis).

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