Having trouble with go-sdl2

<p>I&#39;m very new to SDL and I&#39;m trying to write a function that allows me to do pixel art game or pure pixel drawing in SDL. I tried piecing together a working program that would atleast allow me to draw pixel at every iteration and make a simple animation.</p> <p><a href="https://gist.github.com/boarpig/d09e419b427c8c2da440">Here&#39;s what I did so far</a> </p> <p>But I ran into trouble because I couldn&#39;t make heads or tail from go&#39;s pointer and int conversions. What I understand is that texture.Lock() is supposed to give me a pointer to pixel data that I can draw into and then save it with texture.Update and then Unlock it.</p> <p>Thank you very much!</p> <hr/>**评论：**<br/><br/>calebdoxsey: <pre><p>I don&#39;t think you&#39;re far off:</p> <pre><code>var pixels unsafe.Pointer var pitch int err = texture.Lock(nil, &amp;pixels, &amp;pitch) if err != nil { panic(err) } for x := 0; x &lt; w; x++ { for y := 0; y &lt; h; y++ { (*[w * h]uint32)(pixels)[y*(pitch/4)+x] = 100 // whatever color you want } } texture.Update(nil, pixels, pitch) texture.Unlock() </code></pre> <p>The main differences:</p> <ol> <li>divide the pitch by 4 since its in bytes but you are using uint32s</li> <li>lock / unlock outside of the loop</li> <li>use two loops for x &amp; y so the break condition is obvious</li> </ol> <p><code>w</code> and <code>h</code> have to be constant in this example, but it really just needs to be a large number. This is a general trick when using unsafe pointers which you can also use to do zero-cost conversions: <a href="https://github.com/calebdoxsey/tutorials/blob/master/integration/shm/main.go#L86" rel="nofollow">https://github.com/calebdoxsey/tutorials/blob/master/integration/shm/main.go#L86</a>.</p> <p>I&#39;d recommend making something like a Pixels or Bitmap struct which you can use for your drawing code, then passing that into the SDL methods. It could be as simple as:</p> <pre><code>type Pixels struct { unsafe.Pointer } </code></pre> <p>And just add methods like:</p> <pre><code>func (px Pixels) Get(x, y int) uint32 func (px Pixels) Set(x, y int, color uint32) </code></pre> <p>So you can hide the type conversions.</p></pre>boarhog: <pre><p>Thanks, it seems to work now. Thanks a lot for you help!</p> <p>Here&#39;s a updated copy</p> <p><a href="https://gist.github.com/boarpig/d09e419b427c8c2da440" rel="nofollow">https://gist.github.com/boarpig/d09e419b427c8c2da440</a></p> <p>I&#39;ll look into abstracting those pixels later :)</p></pre>