gradient

I would like to draw a circular gradient like in the example picture below. I can manage a radial gradient easily but I am not sure how to do a circular one. I was thinking of drawing a gradient on a line and then transforming it to a circle. Would that be possible? This is how I draw the radial gradient: CGFloat a = MIN(self.frame.size.width, self.frame.size.height) - _lineWidth; //Get current context CGContextRef mainContext = UIGraphicsGetCurrentContext(); CGRect newRect = rect; newRect.origin.x = ((self.frame.size.width - a)/2.0f); newRect.origin.y = ((self.frame.size.height - a)/2.0f);

I am trying to get the Gradient Vector Field of an image using Python (similar to this matlab question ). This is the original image: Here is my code: import numpy as np import matplotlib.pyplot as plt import Image from PIL import ImageFilter I = Image.open('test.png').transpose(Image.FLIP_TOP_BOTTOM) I = I.filter(ImageFilter.BLUR) p = np.asarray(I) w,h = I.size y, x = np.mgrid[0:h:500j, 0:w:500j] dy, dx = np.gradient(p) skip = (slice(None, None, 3), slice(None, None, 3)) fig, ax = plt.subplots() im = ax.imshow(I, extent=[x.min(), x.max(), y.min(), y.max()]) ax.quiver(x[skip], y[skip], dx[skip

I would like to know how does numpy.gradient work. I used gradient to try to calculate group velocity (group velocity of a wave packet is the derivative of frequencies respect to wavenumbers, not a group of velocities). I fed a 3 column array to it, the first 2 colums are x and y coords, the third column is the frequency of that point (x,y). I need to calculate gradient and I did expect a 2d vector, being gradient definition df/dx*i+df/dy*j+df/dz*k and my function only a function of x and y i did expect something like df/dx*i+df/dy*j But i got 2 arrays with 3 colums each, i.e. 2 3d vectors; at

I'm trying to create an OpenGL ES 2.0 fragment shader that outputs multiple stop gradient along one axis. It should interpolate between multiple colors at points defined in percents. I've achieved this by using if s the fragment shader, like this: float y = gl_FragCoord.y; float step1 = resolution.y * 0.20; float step2 = resolution.y * 0.50; if (y < step1) { color = white; } else if (y < step2) { float x = smoothstep(step1, step2, y); color = mix(white, red, x); } else { float x = smoothstep(step2, resolution.y, y); color = mix(red, green, x); } They say that branching in fragment shader can

I've been following the lessons about transparency and gradients on the Mozilla site: https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/Canvas_tutorial/Applying_styles_and_colors but I have not been able to figure this one out. I know I can achieve these effects with a png image; however, in the program I am working on the gradient will change constantly according to where the image is moved. Here's an example of the effect I'm looking for. http://home.insightbb.com/~epyonxl1/gradientex.jpg I've aded some code here http://code.google.com/p/canvasimagegradient/ that adds a

I would like to create effect like on this image - gradient opacity on the bottom of content: How can i do it? Love Trivedi You can use this HTML <div class="content"> Loriem ispsum is simply dummy text<br> Loriem ispsum is simply dummy text<br> Loriem ispsum is simply dummy text<br> Loriem ispsum is simply dummy text<br> Loriem ispsum is simply dummy text<br> Loriem ispsum is simply dummy text<br> Loriem ispsum is simply dummy text<br> Loriem ispsum is simply dummy text<br> Loriem ispsum is simply dummy text<br> Loriem ispsum is simply dummy text<br> Loriem ispsum is simply dummy text<br>

I am trying to achieve a gradient + text shadow effect in Chrome/Safari using CSS text-shadow and a combination of text-shadow and background-image: -webkit-gradient, see example blw. I can only make one of the effects apply(if I add the shadow the gradient disappears. What am I doing wrong? h1 { font-size: 100px; background-image: -webkit-gradient(linear, left top, left bottom, from(white), to(black)); -webkit-background-clip: text; -webkit-text-fill-color: transparent; text-shadow: 0 1px 1px #fff; } The gradient "disappears" because the text-shadow is on a level above the background. The