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2 posts
Day 004: Memory Allignment in Bitmap Memory
Edited by chelges1 on Reason: Initial post
Hello, I am a novice programmer with some experience in Java and C. A few months ago, I discovered Handmade Hero and I recently decided I would work my way through it.

I am currently on Day 4: Animating a Backbuffer, and I've found myself mentally stuck at the point where Casey makes two for loops to animate the pixels within the back buffer (aka the BitmapMemory).

Though I understand that the program is iterating through each row and each pixel, I do not understand why the Rows are unsigned 8 bit integers while the pixels are unsigned 32 bit integers.

I supposed Casey wanted to format the allocated memory into sections of eight bits, then format it into sections of 32 bits, but why not start by casting Row to a uint32 over a unit8?

If anyone has an explanation, or if there is greater detail in a later episode, let me know.
18 posts
Day 004: Memory Allignment in Bitmap Memory
Edited by William on
Row always points to the start of the row, which is done by advancing it by the Pitch each time.

Pitch is the size of each row in bytes - not pixels.

If instead Row was a uint32, then advancing it by Pitch would actually move it by Pitch*sizeof(uint32) bytes instead of Pitch bytes, because pointers move in multiples of the size of the type they point to.