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2014/10/15 ¤U¤È 10:11:19
iphone Programming Glossary: matrixHow to do antialiasing on a rotated view? [duplicate] http://stackoverflow.com/questions/1315772/how-to-do-antialiasing-on-a-rotated-view no antialiasing happening at all. Also if it's a UIImageView no antialiasing happens when rotating the transform matrix. Is there a way to achieve smooth edges and smooth rotation of images iphone cocoa touch uikit share improve this question..
How do I create/render a UIImage from a 3D transformed UIImageView? http://stackoverflow.com/questions/1949003/how-do-i-create-render-a-uiimage-from-a-3d-transformed-uiimageview float zDistance 250 CATransform3D transform3D CATransform3DIdentity transform3D.m34 1.0 zDistance the m34 cell of the matrix controls perspective and zDistance affects the sharpness of the transform transform3D CATransform3DRotate transform3D DEGREES_TO_RADIANS.. float zDistance 250 CATransform3D transform3D CATransform3DIdentity transform3D.m34 1.0 zDistance the m34 cell of the matrix controls perspective and zDistance affects the sharpness of the transform transform3D CATransform3DRotate transform3D DEGREES_TO_RADIANS.. the original UIImageView into a UIImage. Then every pixel in the UIImage is multiplied by the inverse transform matrix to generate the transformed UIImage. RenderUIImageView.h #import UIKit UIKit.h #import QuartzCore CATransform3D.h #import..
iphone sdk CGAffineTransform getting the angle of rotation of an object http://stackoverflow.com/questions/2051811/iphone-sdk-cgaffinetransform-getting-the-angle-of-rotation-of-an-object which turns the image into a parallelogram and the rotation angle isn't defined anymore. Anyway since the rotation matrix generates cos x sin x 0 sin x cos x 0 0 0 1 You can recover the angle with return atan2 transform.b transform.a share..
FFmpeg on iPhone - Modifying Video Orientation http://stackoverflow.com/questions/2208522/ffmpeg-on-iphone-modifying-video-orientation loaded with FFmpeg on the iPhone 3GS. The problem is any videos recorded in Portrait orientation have a transformation matrix applied to them causing them to display rotated 90 degrees counter clock. From what I understand thus far I just need to.. them to display rotated 90 degrees counter clock. From what I understand thus far I just need to modify the transform matrix in the 'tkhd' atom. The problem is I am having trouble accessing or modifying this data. I checked out the FFmpeg implementation.. implementation for static int mov_read_tkhd MOVContext c ByteIOContext pb MOVAtom atom which clearly shows how the matrix is accessed in avformat but when I try to access the header bytes using the same functions I am not getting any rational..
iPhone image stretching (skew) http://stackoverflow.com/questions/2351586/iphone-image-stretching-skew m31 m32 m33 m34 CGFloat m41 m42 m43 m44 typedef struct CATransform3D CATransform3D So you can directly change the matrix elements instead of relying on the CATransform3DMake functions. You may need to perform a transpose due to convention of.. quadrilateral x1a y1a x2a y2a x3a y3a x4a y4a use this function you may need a transpose function compute_transform_matrix X Y W H x1a y1a x2a y2a x3a y3a x4a y4a var y21 y2a y1a y32 y3a y2a y43 y4a y3a y14 y1a y4a y31 y3a y1a y42 y4a y2a var..
iPhone OpenGL ES - How to Pick http://stackoverflow.com/questions/2540447/iphone-opengl-es-how-to-pick there any helpers to do the reverse of last few transforms which I do for navigation or I should calculate and do the matrix stuff by hand iphone opengl es matrix touch share improve this question Picking mode is not available in openGL ES... last few transforms which I do for navigation or I should calculate and do the matrix stuff by hand iphone opengl es matrix touch share improve this question Picking mode is not available in openGL ES. But it's easy to calculate the screen.. is not available in openGL ES. But it's easy to calculate the screen coordinate of any 3d point using the projection matrix retrieved from current openGL state. Here is how I do it IMPoint2D and IMPoint3D are basic x y and x y z structures IMPoint2D..
http://stackoverflow.com/questions/3245733/apple-gyroscope-sample-code OpenGL is pretty simple. You need to get the current gyro attitude rotation and then store it in an OpenGL compatible matrix. The code below retrieves and saves the current device motion. GLfloat rotMatrix 16 void getDeviceGLRotationMatrix CMDeviceMotion..
How do I apply a perspective transform to a UIView? http://stackoverflow.com/questions/347721/how-do-i-apply-a-perspective-transform-to-a-uiview perform the layer's rotation. The trick to get perspective working as described here is to directly access one of the matrix cells of the CATransform3D m34 . Matrix math has never been my thing so I can't explain exactly why this works but it does...
Convert decimal to fraction in Objective-C? http://stackoverflow.com/questions/5552537/convert-decimal-to-fraction-in-objective-c this series with some adjustments in the last term . Note the fraction can be recovered as the first column of the matrix a1 1 a2 1 a3 1 ... 1 0 1 0 1 0 Instead of keeping the sequence of continued fraction terms we just keep the last partial.. long maxDenominator double atof int atoi void exit long m 2 2 double startx long ai startx realNumber initialize matrix m 0 0 m 1 1 1 m 0 1 m 1 0 0 loop finding terms until denom gets too big while m 1 0 ai long realNumber m 1 1 maxDenominator..
Store orientation to an array - and compare http://stackoverflow.com/questions/6368618/store-orientation-to-an-array-and-compare to this paper subsection 2.1 D i j Dist i j MIN D i 1 j D i j 1 D i 1 j 1 Here D i j is the i j element of the cost matrix see below. Check Figure 3 of that paper to see this recurrence relation is applied. In short columns are computed first..
Transforming a rectangle image into a quadrilateral using a CATransform3D http://stackoverflow.com/questions/9470493/transforming-a-rectangle-image-into-a-quadrilateral-using-a-catransform3d the perspective of the image moving in space it is in fact the combination of a scale a rotation and a perspective matrix. I am wondering if this is possible using a CATransform3D 4x4 matrix. Do you have any hints on how to do that I've tried.. of a scale a rotation and a perspective matrix. I am wondering if this is possible using a CATransform3D 4x4 matrix. Do you have any hints on how to do that I've tried to take the four points and build 16 equations out of A' A x u but it..
http://stackoverflow.com/questions/10232539/how-to-approach-hd-files with VBO support in TextureAtlas YES 2012 04 19 17 14 29.236 ParallaxNodeTest 3713 10a03 cocos2d compiled with Affine Matrix transformation in CCNode YES 2012 04 19 17 14 29.237 ParallaxNodeTest 3713 10a03 cocos2d compiled with Profiling Support..
Advice on speeding up OpenGL ES 1.1 on the iPhone http://stackoverflow.com/questions/1844765/advice-on-speeding-up-opengl-es-1-1-on-the-iphone will give me the most bang for the buck. My scene rendering goes something like this Repeat 35 times glPushMatrix glLoadIdentity glTranslate Repeat 7 times glBindTexture glVertexPointer glNormalPointer glTexCoordPointer glDrawArrays GL_TRIANGLES.. Repeat 7 times glBindTexture glVertexPointer glNormalPointer glTexCoordPointer glDrawArrays GL_TRIANGLES ... glPopMatrix My Vertex Normal and Texture Coords are already interleaved. So what steps should I take to speed this up What step would.. is hovering around 50 . I suppose this might have something to do with scaling the texture coordinates from GL_TEXTURE Matrix Mode. I'm still seeking additional improvements. I'd like to get closer to 40 FPS as that's what my iPod Touch gets and..
Using quaternion instead of roll, pitch and yaw to track device motion http://stackoverflow.com/questions/19239482/using-quaternion-instead-of-roll-pitch-and-yaw-to-track-device-motion if you already made friends with them . I recommend OpenGL Tutorials Using Quaternions to represent rotation or The Matrix and Quaternions FAQ . It helps to bear in mind that x y z represent the axis to rotate around not normalised and w cos alpha..
iPhone OpenGL ES - How to Pick http://stackoverflow.com/questions/2540447/iphone-opengl-es-how-to-pick z structures IMPoint2D getScreenCoorOfPoint IMPoint3D _point3D GLfloat p 16 Where The 16 Doubles Of The Projection Matrix Are To Be Stored glGetFloatv GL_PROJECTION_MATRIX p Retrieve The Projection Matrix Multiply M point GLfloat _p p 0 _point3D.x.. The 16 Doubles Of The Projection Matrix Are To Be Stored glGetFloatv GL_PROJECTION_MATRIX p Retrieve The Projection Matrix Multiply M point GLfloat _p p 0 _point3D.x p 4 _point3D.y p 8 _point3D.z p 12 p 1 _point3D.x p 5 _point3D.y p 9 _point3D.z..
How do I apply a perspective transform to a UIView? http://stackoverflow.com/questions/347721/how-do-i-apply-a-perspective-transform-to-a-uiview to get perspective working as described here is to directly access one of the matrix cells of the CATransform3D m34 . Matrix math has never been my thing so I can't explain exactly why this works but it does. You'll need to set this value to a negative..
How can I rotate an UIImageView by 20 degrees? http://stackoverflow.com/questions/852863/how-can-i-rotate-an-uiimageview-by-20-degrees an UIImageView I have an image which I want to rotate by 20 degrees. The Apple Docs talk about an transformation Matrix but that sounds incredible difficult. Are there any helpful methods or functions to achieve that iphone cocoa touch uikit..
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