From 1f5b1ad1ab038bfef67448a3242546a012041498 Mon Sep 17 00:00:00 2001
From: Sergio Valor <jaildesigner@gmail.com>
Date: Sat, 18 Apr 2026 11:55:12 +0200
Subject: [PATCH] =?UTF-8?q?surface:=20hallazgo=202=20=E2=80=94=20drawLine?=
 =?UTF-8?q?=20con=20Bresenham=20en=20enteros?=
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El bucle usaba floats con comparación de igualdad exacta (x1==x2 &&
y1==y2) como condición de parada, con incrementos ±1.0f acumulados:
bug latente. Convertidos los endpoints de entrada con std::lround y
reescrito el algoritmo con ints. Firma pública float preservada para
no tocar callers.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 source/core/rendering/surface.cpp | 43 ++++++++++++++++---------------
 1 file changed, 22 insertions(+), 21 deletions(-)

diff --git a/source/core/rendering/surface.cpp b/source/core/rendering/surface.cpp
index de32ec2..ae85e1c 100644
--- a/source/core/rendering/surface.cpp
+++ b/source/core/rendering/surface.cpp
@@ -211,37 +211,38 @@ void Surface::drawRectBorder(const SDL_FRect* rect, Uint8 color) {  // NOLINT(re
     }
 }
 
-// Dibuja una linea
+// Dibuja una linea (Bresenham en enteros)
 void Surface::drawLine(float x1, float y1, float x2, float y2, Uint8 color) {  // NOLINT(readability-convert-member-functions-to-static)
-    // Calcula las diferencias
-    float dx = std::abs(x2 - x1);
-    float dy = std::abs(y2 - y1);
+    int ix1 = static_cast<int>(std::lround(x1));
+    int iy1 = static_cast<int>(std::lround(y1));
+    const int IX2 = static_cast<int>(std::lround(x2));
+    const int IY2 = static_cast<int>(std::lround(y2));
 
-    // Determina la dirección del incremento
-    float sx = (x1 < x2) ? 1 : -1;
-    float sy = (y1 < y2) ? 1 : -1;
+    const int DX = std::abs(IX2 - ix1);
+    const int DY = std::abs(IY2 - iy1);
+    const int SX = (ix1 < IX2) ? 1 : -1;
+    const int SY = (iy1 < IY2) ? 1 : -1;
 
-    float err = dx - dy;
+    const int SURF_W = static_cast<int>(surface_data_->width);
+    const int SURF_H = static_cast<int>(surface_data_->height);
+    Uint8* data_ptr = surface_data_->data.get();
 
+    int err = DX - DY;
     while (true) {
-        // Asegúrate de no dibujar fuera de los límites de la superficie
-        if (x1 >= 0 && x1 < surface_data_->width && y1 >= 0 && y1 < surface_data_->height) {
-            surface_data_->data.get()[static_cast<size_t>(x1 + (y1 * surface_data_->width))] = color;
+        if (ix1 >= 0 && ix1 < SURF_W && iy1 >= 0 && iy1 < SURF_H) {
+            data_ptr[ix1 + (iy1 * SURF_W)] = color;
         }
-
-        // Si alcanzamos el punto final, salimos
-        if (x1 == x2 && y1 == y2) {
+        if (ix1 == IX2 && iy1 == IY2) {
             break;
         }
-
         int e2 = 2 * err;
-        if (e2 > -dy) {
-            err -= dy;
-            x1 += sx;
+        if (e2 > -DY) {
+            err -= DY;
+            ix1 += SX;
         }
-        if (e2 < dx) {
-            err += dx;
-            y1 += sy;
+        if (e2 < DX) {
+            err += DX;
+            iy1 += SY;
         }
     }
 }