From d8789b76898f65ecdef4f2b0febfa7ab5b147720 Mon Sep 17 00:00:00 2001
From: Fierelier <fier@airmail.cc>
Date: Wed, 25 Sep 2024 21:12:28 +0200
Subject: [PATCH] Speed up and fix unigi_ext_texture_draw

---
 main.c | 84 ++++++++++++++++++++++++++--------------------------------
 main.h |  4 +--
 2 files changed, 40 insertions(+), 48 deletions(-)

diff --git a/main.c b/main.c
index 7f8f35b..a0287ae 100644
--- a/main.c
+++ b/main.c
@@ -1,51 +1,43 @@
 #include "unigi.ext/main.h"
 
-void unigi_ext_texture_draw(
-	unigi_ext_type_texture tex,
-	unigi_ext_type_texture buffer,
-	unigi_ext_type_rect texbounds,
-	unigi_ext_type_rect bufbounds
-) {
-   unigi_ext_type_2d_coord texwidth;
-   unigi_ext_type_2d_coord texheight;
-   unigi_ext_type_2d_coord outwidth;
-   unigi_ext_type_2d_coord outheight;
-   unigi_ext_type_2d_coord x;
-   unigi_ext_type_2d_coord y;
-   unigi_type_resolution_1d_coord texi;
-   unigi_type_resolution_1d_coord bufi;
-   unigi_ext_type_2d_coord stepx;
-   unigi_ext_type_2d_coord stepy;
-   unigi_ext_type_2d_coord texx;
-   unigi_ext_type_2d_coord texy;
-   
-   unigi_ext_rect_dimensions(texbounds, &texwidth, &texheight);
-   unigi_ext_rect_dimensions(bufbounds, &outwidth, &outheight);
-   // We precalculate the step through the texture to avoid division and
-   // 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. 
-   stepx = (1 << unigi_ext_texture_fixedpointdepth) * (float)texwidth / outwidth;
-   stepy = (1 << unigi_ext_texture_fixedpointdepth) * (float)texheight / outheight;
-   texx = (1 << unigi_ext_texture_fixedpointdepth) * texbounds.x1;
-   texy = (1 << unigi_ext_texture_fixedpointdepth) * texbounds.y1;
-   //log("%f,%f step %f,%f", texx, texy, stepx, stepy);
-   // Buffer is R G B for each pixel, then across then down. If you want X, Y,
-   // it's: 3 * (x + y * width)
-   for(y = bufbounds.y1; y < bufbounds.y2; y++) {
-      texx = texbounds.x1;
-      for(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
-         texi = (texx >> unigi_ext_texture_fixedpointdepth) + tex.width * (texy >> unigi_ext_texture_fixedpointdepth); // 'texy >> FIXEDPOINTDEPTH' could be calculated per y-iteration
-         bufi = x + y * buffer.width; // 'y * buffer.width' could be calculated per y-iteration
-         buffer.pixels[bufi] = tex.pixels[texi];
-         texx += stepx;
-         bufi += 1;
-      }
-      texy += stepy;
-   }
+void unigi_ext_texture_draw(unigi_ext_type_texture *sprite, unigi_ext_type_texture *fb, unigi_ext_type_rect texrect, unigi_ext_type_rect outrect) {
+	// Precalc the step, as it's always the same even if we clip the rect
+	unigi_ext_type_2d_coord tex_width, tex_height, out_width, out_height;
+	unigi_ext_rect_dimensions(texrect,&tex_width,&tex_height);
+	unigi_ext_rect_dimensions(outrect,&out_width,&out_height);
+	int32_t stepx = (1 << unigi_ext_texture_fixedpointdepth) * (float)tex_width / out_width;
+	int32_t stepy = (1 << unigi_ext_texture_fixedpointdepth) * (float)tex_height / out_height;
+	int32_t texx_init = (1 << unigi_ext_texture_fixedpointdepth) * texrect.x1;
+	int32_t texy = (1 << unigi_ext_texture_fixedpointdepth) * texrect.y1;
+	// Clip the rect
+	if (outrect.x1 < 0) {
+		texx_init += stepx * -outrect.x1;
+		outrect.x1 = 0;
+	}
+	if (outrect.y1 < 0) {
+		texy += stepy * -outrect.y1;
+		outrect.y1 = 0;
+	}
+	if (outrect.x2 >= fb->width) {
+		outrect.x2 = fb->width - 1;
+	}
+	if (outrect.y2 >= fb->height) {
+		outrect.y2 = fb->height - 1;
+	}
+	
+	for (int y = outrect.y1; y < outrect.y2; y++) {
+		int32_t texx = texx_init;
+		int yiter = y * fb->width;
+		for (int x = outrect.x1; x < outrect.x2; x++) {
+			uint16_t pix = sprite->pixels[((texy >> unigi_ext_texture_fixedpointdepth) * sprite->width) + (texx >> unigi_ext_texture_fixedpointdepth)];
+			
+			if (pix & 0xF000) {
+		fb->pixels[yiter + x] = pix;
+			}
+			texx += stepx;
+		}
+		texy += stepy;
+	}
 }
 
 unigi_ext_type_texture * unigi_ext_texture_create(unigi_ext_type_2d_coord width, unigi_ext_type_2d_coord height) {
diff --git a/main.h b/main.h
index 97f99f3..bfbfea4 100644
--- a/main.h
+++ b/main.h
@@ -5,8 +5,8 @@
 #include "structs.h"
 
 void unigi_ext_texture_draw(
-	unigi_ext_type_texture tex,
-	unigi_ext_type_texture buffer,
+	unigi_ext_type_texture * tex,
+	unigi_ext_type_texture * buffer,
 	unigi_ext_type_rect texbounds,
 	unigi_ext_type_rect bufbounds
 );