blending

In Apple's GLPaint example, the user can draw with semi-transparent brush over a surface and change colours. However, as of iOS7, for some odd reason it is not possible to draw something that completely goes over its background: In the first image, we see "Shake me" written with green and a red blob that was drawn multiple times over it. Yet, the writing bellow is still barely visible. The second image was desaturated to make the defect more obvious. The OpenGL blending function Apple is using is: glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA); What I expect it to do is to blend the newer semi

I want to blend two images using multiband blending but I am not clear to the input parameter of this function: void detail::Blender::prepare(const std::vector<Point>& corners, const std::vector<Size>& sizes) In my case ,I just input two warped images with black gap, and with masks all white.(forgive me can not add pictures...) And I set the two corners (0.0,0.0),because the warped images has been registered. but my result is not good enough.with obvious seam in the result can someone tell me why?How can I solve this problem? I'm not sure what do you mean when you say "my result is not good

I'm trying to colorize a spriteNode (in this case its named background) using sprite kit but cant get the color to change. I have a sprite that I want to colorize. I'm changing the color property of the sprite as well as the color blending factor. When I run the app nothing happens though. the color remains the same (its black right now). below is the code I'm using to change the color: background.anchorPoint = CGPointMake(0, .5); background.position = position; // ... // this does not seems to be doing anything at all background.color = [SKColor redColor]; background.colorBlendFactor = 1.0f;

I need to have an Image blended together with an red square in mode multiply. As I know, IE and Safari doesn't support the css-property "blend-mode", so I tried it with blending them together in a canvas and everything worked fine - except in IE. Is there any way to get those blended together in IE or isn't that supported yet? markE For Internet Explorer, Canvas blending modes are "under consideration". https://developer.microsoft.com/en-us/microsoft-edge/platform/status/mixblendmode/?q=blend Until blends are implemented in IE, you can roll-your-own multiply filter: function multiply(R, G, B)

I've found a few places where this has been asked, but I've not yet found a good answer. The problem: I want to render to texture, and then I want to draw that rendered texture to the screen IDENTICALLY to how It would appear if I skipped the render to texture step and were just directly rendering to the screen. I am currently using a blend mode glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA). I have glBlendFuncSeparate to play around with as well. I want to be able to render partially transparent overlapping items to this texture. I know the blend function is currently messing up the RGB

I have a problem: I need to be able to take two colors and make a 'virtual gradient' out of them. I then need to be able to find the color at any point on this line. My current approach is this: if (fahrenheit < kBottomThreshold) { return [UIColor colorWithRed:kBottomR/255.0f green:kBottomG/255.0f blue:kBottomB/255.0f alpha:1]; } if (fahrenheit > kTopThreshold) { return [UIColor colorWithRed:kTopR/255.0f green:kTopG/255.0f blue:kTopB/255.0f alpha:1]; } double rDiff = kTopR - kBottomR; double gDiff = kTopG - kBottomG; double bDiff = kTopB - kBottomB; double tempDiff = kTopThreshold -