From feb4bc8cbc66ba928319ddb2cc1bf48010487863 Mon Sep 17 00:00:00 2001
From: fschildt <florian.schildt@protonmail.com>
Date: Mon, 24 Nov 2025 18:18:24 +0100
Subject: renderer: improve resizing

---
 src/renderer/RSoftwareBackend.cpp | 66 +++++++++++++++++++++++++--------------
 1 file changed, 42 insertions(+), 24 deletions(-)

(limited to 'src/renderer/RSoftwareBackend.cpp')

diff --git a/src/renderer/RSoftwareBackend.cpp b/src/renderer/RSoftwareBackend.cpp
index d05cee7..587ac74 100644
--- a/src/renderer/RSoftwareBackend.cpp
+++ b/src/renderer/RSoftwareBackend.cpp
@@ -1,4 +1,3 @@
-#include "imgui.h"
 #include <renderer/RSoftwareBackend.hpp>
 
 #include <SDL3/SDL_video.h>
@@ -25,33 +24,19 @@ RSoftwareBackend::RSoftwareBackend(Renderer& renderer)
     glGenTextures(1, &m_gltexture_id);
     glBindTexture(GL_TEXTURE_2D, m_gltexture_id);
 
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);	
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-}
-
-void
-RSoftwareBackend::ResizeCanvas(int32_t w, int32_t h)
-{
-    size_t realloc_size = (size_t)(w * h) * sizeof(m_canvas.pixels[0]);
-    void *realloc_data = realloc(m_canvas.pixels, realloc_size);
-    if (!realloc_data) {
-        printf("could not resize offscreen buffer\n");
-        return;
-    }
-
-    m_canvas.w = w;
-    m_canvas.h = h;
-    m_canvas.pixels = (uint32_t*)realloc_data;
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 }
 
 void
 RSoftwareBackend::Draw()
 {
-    ResizeCanvas(m_renderer.m_screen_w, m_renderer.m_screen_h);
-    SortRenderEntities();
+    Resize(m_renderer.m_screen_w, m_renderer.m_screen_h);
+    DrawClear();
 
+    SortRenderEntities();
 
     for (RSortEntry sort_entry : m_renderer.m_sort_entries) {
         REntity& entity = m_renderer.m_render_entities[sort_entry.entity_index];
@@ -76,7 +61,6 @@ RSoftwareBackend::Draw()
     }
 
 
-    glActiveTexture(GL_TEXTURE0);
     glBindTexture(GL_TEXTURE_2D, m_gltexture_id);
     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_canvas.w, m_canvas.h, 0, GL_RGBA, GL_UNSIGNED_BYTE, m_canvas.pixels);
 
@@ -86,8 +70,23 @@ RSoftwareBackend::Draw()
     glTexCoord2f(1.0f, 1.0f); glVertex2f( 1.0f,  1.0f);
     glTexCoord2f(0.0f, 1.0f); glVertex2f(-1.0f,  1.0f);
     glEnd();
+}
+
+void
+RSoftwareBackend::Resize(int32_t w, int32_t h)
+{
+    size_t realloc_size = (size_t)(w * h) * sizeof(m_canvas.pixels[0]);
+    void *realloc_data = realloc(m_canvas.pixels, realloc_size);
+    if (!realloc_data) {
+        printf("could not resize offscreen buffer\n");
+        return;
+    }
 
-    glBindTexture(GL_TEXTURE_2D, 0);
+    m_canvas.w = w;
+    m_canvas.h = h;
+    m_canvas.pixels = (uint32_t*)realloc_data;
+
+    glViewport(0, 0, w, h);
 }
 
 void
@@ -100,6 +99,25 @@ RSoftwareBackend::SortRenderEntities()
               });
 }
 
+void
+RSoftwareBackend::DrawClear()
+{
+    Color color = m_renderer.m_clear_color;
+    uint32_t rshift = m_canvas.rshift;
+    uint32_t gshift = m_canvas.gshift;
+    uint32_t bshift = m_canvas.bshift;
+
+    for (int32_t y = 0; y < m_canvas.h; y++) {
+        for (int32_t x = 0; x < m_canvas.w; x++) {
+            uint32_t r = (uint32_t)(color.r * 255.0f);
+            uint32_t g = (uint32_t)(color.g * 255.0f);
+            uint32_t b = (uint32_t)(color.b * 255.0f);
+            uint32_t val = r << rshift | g << gshift | b << bshift;
+            m_canvas.pixels[y*m_canvas.w + x] = val;
+        }
+    }
+}
+
 void
 RSoftwareBackend::DrawRectangle(REntity_Rectangle& entity)
 {
-- 
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