From 4b0f729d528061d34bbd8bbdcd7c383b8489101a Mon Sep 17 00:00:00 2001
From: Roman Fomin <rfomin@gmail.com>
Date: Wed, 21 Feb 2024 17:43:35 +0700
Subject: [PATCH] bring back clipping to v_video functions (#1518)

* add clipping to V_FillRect

* add clipping to V_CopyRect
---
 src/v_video.c | 83 +++++++++++++++++++++++++++++++--------------------
 1 file changed, 51 insertions(+), 32 deletions(-)

diff --git a/src/v_video.c b/src/v_video.c
index d09fc122a..6bfc3df92 100644
--- a/src/v_video.c
+++ b/src/v_video.c
@@ -632,6 +632,35 @@ int V_ScaleY(int y)
     return y1lookup[y];
 }
 
+static void V_ClipRect(vrect_t *rect)
+{
+    // clip to left and top edges
+    rect->cx1 = rect->x >= 0 ? rect->x : 0;
+    rect->cy1 = rect->y >= 0 ? rect->y : 0;
+
+    // determine right and bottom edges
+    rect->cx2 = rect->x + rect->w - 1;
+    rect->cy2 = rect->y + rect->h - 1;
+
+    // clip right and bottom edges
+    if (rect->cx2 >= video.unscaledw)
+        rect->cx2 =  video.unscaledw - 1;
+    if (rect->cy2 >= SCREENHEIGHT)
+        rect->cy2 =  SCREENHEIGHT - 1;
+
+    // determine clipped width and height
+    rect->cw = rect->cx2 - rect->cx1 + 1;
+    rect->ch = rect->cy2 - rect->cy1 + 1;
+}
+
+static void V_ScaleClippedRect(vrect_t *rect)
+{
+    rect->sx = x1lookup[rect->cx1];
+    rect->sy = y1lookup[rect->cy1];
+    rect->sw = x2lookup[rect->cx2] - rect->sx + 1;
+    rect->sh = y2lookup[rect->cy2] - rect->sy + 1;
+}
+
 void V_FillRect(int x, int y, int width, int height, byte color)
 {
     vrect_t dstrect;
@@ -641,7 +670,13 @@ void V_FillRect(int x, int y, int width, int height, byte color)
     dstrect.w = width;
     dstrect.h = height;
 
-    V_ScaleRect(&dstrect);
+    V_ClipRect(&dstrect);
+
+    // clipped away completely?
+    if (dstrect.cw <= 0 || dstrect.ch <= 0)
+        return;
+
+    V_ScaleClippedRect(&dstrect);
 
     byte* dest = V_ADDRESS(dest_screen, dstrect.sx, dstrect.sy);
 
@@ -683,13 +718,26 @@ void V_CopyRect(int srcx, int srcy, pixel_t *source,
     srcrect.w = width;
     srcrect.h = height;
 
+    V_ClipRect(&srcrect);
+
+    // clipped away completely?
+    if (srcrect.cw <= 0 || srcrect.ch <= 0)
+        return;
+
+    V_ScaleClippedRect(&srcrect);
+
     dstrect.x = destx;
     dstrect.y = desty;
     dstrect.w = width;
     dstrect.h = height;
 
-    V_ScaleRect(&srcrect);
-    V_ScaleRect(&dstrect);
+    V_ClipRect(&dstrect);
+
+    // clipped away completely?
+    if (dstrect.cw <= 0 || dstrect.ch <= 0)
+        return;
+
+    V_ScaleClippedRect(&dstrect);
 
     // use the smaller of the two scaled rect widths / heights
     usew = (srcrect.sw < dstrect.sw ? srcrect.sw : dstrect.sw);
@@ -706,35 +754,6 @@ void V_CopyRect(int srcx, int srcy, pixel_t *source,
     }
 }
 
-static void V_ClipRect(vrect_t *rect)
-{
-    // clip to left and top edges
-    rect->cx1 = rect->x >= 0 ? rect->x : 0;
-    rect->cy1 = rect->y >= 0 ? rect->y : 0;
-
-    // determine right and bottom edges
-    rect->cx2 = rect->x + rect->w - 1;
-    rect->cy2 = rect->y + rect->h - 1;
-
-    // clip right and bottom edges
-    if (rect->cx2 >= video.unscaledw)
-        rect->cx2 =  video.unscaledw - 1;
-    if (rect->cy2 >= SCREENHEIGHT)
-        rect->cy2 =  SCREENHEIGHT - 1;
-
-    // determine clipped width and height
-    rect->cw = rect->cx2 - rect->cx1 + 1;
-    rect->ch = rect->cy2 - rect->cy1 + 1;
-}
-
-static void V_ScaleClippedRect(vrect_t *rect)
-{
-    rect->sx = x1lookup[rect->cx1];
-    rect->sy = y1lookup[rect->cy1];
-    rect->sw = x2lookup[rect->cx2] - rect->sx + 1;
-    rect->sh = y2lookup[rect->cy2] - rect->sy + 1;
-}
-
 //
 // V_DrawBlock
 //