From 22ad42b6202f72034afae46031f79dae23d65a5f Mon Sep 17 00:00:00 2001
From: Carlos Sanchez <randomouscrap98@aol.com>
Date: Mon, 22 Jul 2024 21:11:03 -0400
Subject: [PATCH] More comments on float to fixed point

---
 main.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/main.c b/main.c
index 5992f50..a225a08 100644
--- a/main.c
+++ b/main.c
@@ -53,7 +53,10 @@ void drawTexInto(struct texture tex, struct texture buffer, struct rect texbound
    rect_dims(texbounds, &texwidth, &texheight);
    rect_dims(bufbounds, &outwidth, &outheight);
    // We precalculate the step through the texture to avoid division and
-   // multiplication per pixel
+   // multiplication per pixel. We also expand the range so we can use
+   // integers. By using 256, we are essentially adding 8 bits of "decimal
+   // point". If you need more bits (or less), just change this to some other
+   // power of 2. 
    i32 stepx = 256 * (float)texwidth / outwidth;
    i32 stepy = 256 * (float)texheight / outheight;
    i32 texx = 256 * texbounds.x1;
@@ -64,6 +67,8 @@ void drawTexInto(struct texture tex, struct texture buffer, struct rect texbound
    for(int y = bufbounds.y1; y < bufbounds.y2; y++) {
       texx = texbounds.x1;
       for(int x = bufbounds.x1; x < bufbounds.x2; x++) {
+         // And then with the shift, it is log2(256), or whatever you shifted
+         // by up there. So 512 would be 9, because 2^9 = 512
          i32 texi = 3 * ((texx >> 8) + tex.width * (texy >> 8));
          i32 bufi = 3 * (x + y * buffer.width);
          memcpy(buffer.data + bufi, tex.data + texi, 3);
@@ -94,7 +99,7 @@ int main() {
    };
 
    // We actually stretch a texture here
-   struct rect texrect = { 0, 0, 16, 16 };
+   struct rect texrect = { 0, 0, 8, 12 };
    struct rect bufrect = { 10, 10, 509, 499 };
 
    clock_t start = clock();