The final image (which contains the data we need) is formed after the fragment shader execution, so we can’t access it directly from the Cg program. At the same time, the logic of the rendering pipeline won’t allow us to do this directly. In order to get that “ a” layer we need to access the frame buffer, and we need to do this inside the fragment shader to be able to perform the blending algorithm per pixel. However, this step proved to be the most problematic. Having all the blending algorithms implemented it may seem that only the trivial part of the work is left: to get the “ a” - color of the pixels located “behind” our object.

Thus, in general terms, the problem can be summarized as follows: for each pixel of the object ( b) find the pixel that is drawn “behind” it ( a) and blend their colors using selected algorithm. Other modes are implemented in a similar ways and writing about all of them will be boring, so (in case you are interested) I’ve put implementations of the 18 remaining blend modes in Cg here: /Elringus/d21c8b0f87616ede9014. In Darken mode RGB components of the layers are compared and only the “darkest” left in the resulting color. Overlay algorithm is conditional: for the “dark” areas we are multiplying the colors, for “light” - using the expression similar to Screen.įixed4 r = a <. Note we are passing the alpha value of the upper layer ( b.a) to the alpha of the resulting layer ( r.a), to be able to control the opacity of the material. Let’s implement this algorithm using Cg programming language: While in Screen blend mode, colors of both layers are inverted, multiplied, and then inverted again. The most trivial case possible - most of the objects “blends” like this. This is the example of Normal blend mode: each pixel of the lower layer ( a) is completely overridden by the pixels of the layer that covers it ( b). Consider two graphic elements, where one overlaps the other.

In case you are looking for a complete solution to use the blend mode effect in Unity, try this package on the Asset Store: Blending algorithmsįor starters, let’s define what exactly we need to do. In this article I will describe the mechanics behind popular blend modes and try to simulate their effect inside Unity game engine.

Or your UI-artist made a beautiful assets in Photoshop, but some of them are using Soft Light blend mode? Or maybe you’ve wanted to create some weird Lynch-esque effect with Divide blending and apply it to a 3D mesh? Say you need to use Color Dodge blending for a particle system. It is an important technique for content creation and has long since become an integral part of them. You’ve probably heard about blend modes available in image and video editing tools like Photoshop or After Effects.

Opengl es 2.0 merge framebuffer object