alphablending

问题 What Direct3D render states should be used to implement Java's Porter-Duff compositing rules (CLEAR, SRC, SRCOVER, etc.)? 回答1: I'm haven't used Java too much, but based on the white paper from 1984, it should be a fairly straightforward mapping of render state blend modes. There are of course more that you can do than just these, like normal alpha blending (SourceAlpha, InvSourceAlpha) or additive (One, One) to name a few. (I assume that you are asking about these specifically because you are

问题 Alpha blending in same size two images is explained here. How do we implement this for two different size images. Ex: 600x400 pixels PNG for foreground and a 700x380 pixels JPG for background. In the mentioned link, Both the images are same size. 回答1: First of, resizing is a bad idea. Unless both images are resized together (which won't solve the problem), resizing will change the final result in undesired ways (e.g. the foreground object will appear larger than intended). Alpha blending is

问题 Alpha blending in same size two images is explained here. How do we implement this for two different size images. Ex: 600x400 pixels PNG for foreground and a 700x380 pixels JPG for background. In the mentioned link, Both the images are same size. 回答1: First of, resizing is a bad idea. Unless both images are resized together (which won't solve the problem), resizing will change the final result in undesired ways (e.g. the foreground object will appear larger than intended). Alpha blending is

问题 I'm trying to write a fast transparency class in c#. How do I get PNG with transparency into GDI32 to use it with alphaBlend? I tried to put it directly via getHbitmap/selectObject, tried to paint it with setPixel on temporary DC, but all to no avail. 回答1: In the result I found (afer a sleepless night), that simplest of getting transparency into GDI32 is to set Color.Black in GetHbitmap(). Like this: using (Bitmap tBMP = new Bitmap(@"myBitmap.png")) { BMPObject = tBMP.GetHbitmap(Color.Black);

问题 I'm trying to apply a simple alpha mask on a QML item using ShaderEffectItem . Here is a minimal (non-)working example: I have a red-to-white gradient as the background and want to draw a green 200x200 square on top of it. The alpha mask for this square should be 0.0 at the left and 1.0 at the right border, so it should be transparent at the left border. import QtQuick 1.1 import Qt.labs.shaders 1.0 Rectangle { width: 300 height: 300 id: wrapper gradient: Gradient { GradientStop { position: 0

问题 I have an OpenGL RGBA texture and I blit another RGBA texture onto it using a framebuffer object. The problem is that if I use the usual blend functions with glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA), the resulting blit causes the destination texture alpha to change, making it slightly transparent for places where alpha previously was 1. I would like the destination surface alpha never to change, but otherwise the effect on RGB values should be exactly like with GL_SRC_ALPHA and GL

问题 i'm trying to apply a box blur to an transparent image, and i'm getting a "dark halo" around the edges. Jerry Huxtable has a short mention of the problem, and a very good demonstration showing the problem happen: But i, for the life of me, cannot understand how " pre-multiplied alpha " can fix the problem. Now for a very simple example. i have a 3x3 image, containing one red and one green pixel: In reality the remaining pixels are transparent: Now we will apply a 3x3 Box Blur to the image.

问题 I have to present images on a picture control that are a composition of two PNG files, where the top image has transparent pixels on certain positions. The result should of plotter.png with bar.png overlapped on its top appears as (Notice the strange white contours on the bar): but it should be: The code I made for it is simple as CImage image; if (FAILED(image.Load(L"plotter.png"))) return false; CImage imageBar; if (FAILED(imageBar.Load(L"bar.png"))) return false; imageBar.AlphaBlend(image

问题 Is there a way to combine multiple draw operations to a 2d canvas rendering context in such a way that they their combined result is composed onto the previous content of the canvas, as opposed to each drawing operation being composed by itself? One application: I'd like to draw a translucent line with an arrow head, and I'd like to avoid increased opacity in those areas where the line and the arrow head overlap. Many other rendering models support such features. SVG has a group opacity

问题 I have a webcam feed being displayed on my form and would like to draw on top of it. I was going to do this using a picture box, I have found the PictureBox doesn't support true transparency instead just the colour of the form it's on. It also doesn't support alphablending which is how I would want it to display, similar to how forms can be made to appear. Does anyone know how to do this? Or have a control implemented that can do this? 回答1: Transparency in Windows Forms is kind of broken. As