learn-wgpu/assets/js/43.ac6fc643.js

(window.webpackJsonp=window.webpackJsonp||[]).push([[43],{343:function(t,s,a){t.exports=a.p+"assets/img/depth_problems.fde54cff.png"},344:function(t,s,a){t.exports=a.p+"assets/img/forest_fixed.a77f70f6.png"},439:function(t,s,a){"use strict";a.r(s);var e=a(7),n=Object(e.a)({},(function(){var t=this,s=t._self._c;return s("ContentSlotsDistributor",{attrs:{"slot-key":t.$parent.slotKey}},[s("h1",{attrs:{id:"the-depth-buffer"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#the-depth-buffer"}},[t._v("#")]),t._v(" The Depth Buffer")]),t._v(" "),s("p",[t._v("Let's take a closer look at the last example at an angle.")]),t._v(" "),s("p",[s("img",{attrs:{src:a(343),alt:"depth_problems.png"}})]),t._v(" "),s("p",[t._v("Models that should be in the back are getting rendered ahead of ones that should be in the front. This is caused by the draw order. By default, pixel data from a new object will replace old pixel data.")]),t._v(" "),s("p",[t._v("There are two ways to solve this: sort the data from back to front, or use what's known as a depth buffer.")]),t._v(" "),s("h2",{attrs:{id:"sorting-from-back-to-front"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#sorting-from-back-to-front"}},[t._v("#")]),t._v(" Sorting from back to front")]),t._v(" "),s("p",[t._v("This is the go-to method for 2d rendering as it's pretty easy to know what's supposed to go in front of what. You can just use the z order. In 3d rendering, it gets a little trickier because the order of the objects changes based on the camera angle.")]),t._v(" "),s("p",[t._v("A simple way of doing this is to sort all the objects by their distance to the camera's position. There are flaws with this method though as when a large object is behind a small object, parts of the large object that should be in front of the small object will be rendered behind it. We'll also run into issues with objects that overlap "),s("em",[t._v("themselves")]),t._v(".")]),t._v(" "),s("p",[t._v("If we want to do this properly we need to have pixel-level precision. That's where a "),s("em",[t._v("depth buffer")]),t._v(" comes in.")]),t._v(" "),s("h2",{attrs:{id:"a-pixels-depth"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#a-pixels-depth"}},[t._v("#")]),t._v(" A pixels depth")]),t._v(" "),s("p",[t._v("A depth buffer is a black and white texture that stores the z-coordinate of rendered pixels. Wgpu can use this when drawing new pixels to determine whether to replace the data or keep it. This technique is called depth testing. 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