From 98b2b4c64dc3eaa20eabc5a640e9e430d1cc3805 Mon Sep 17 00:00:00 2001
From: John Lorentzson <john_lorentzson@yahoo.com>
Date: Sat, 5 Apr 2025 19:51:34 +0200
Subject: [PATCH] Make compatible with the Sun's pixel format

---
 src/Backends/Platform/X11.cpp                 |  5 ++-
 .../Rendering/Window/Software/X11.cpp         | 42 +++++++------------
 2 files changed, 19 insertions(+), 28 deletions(-)

diff --git a/src/Backends/Platform/X11.cpp b/src/Backends/Platform/X11.cpp
index 8d7ed2b4..1f0cafcf 100644
--- a/src/Backends/Platform/X11.cpp
+++ b/src/Backends/Platform/X11.cpp
@@ -27,8 +27,9 @@ static unsigned long startTime;
 bool Backend_Init(void (*drag_and_drop_callback)(const char *path), void (*window_focus_callback)(bool focus)) {
     // we're ignoring the hell out of focus and drag & drop
     xDisplay = XOpenDisplay(NULL);
-    //XMatchVisualInfo(xDisplay, DefaultScreen(xDisplay), 24, DirectColor, &xvisinfo);
-    //xVisual = xvisinfo.visual;
+    XMatchVisualInfo(xDisplay, DefaultScreen(xDisplay), 24, TrueColor, &xvisinfo);
+    xVisual = xvisinfo.visual;
+    printf("Using X visual with ID 0x%lx\n", xVisual->visualid);
 
     struct timeval time; // time.tv_usec is microseconds
     gettimeofday(&time, NULL);
diff --git a/src/Backends/Rendering/Window/Software/X11.cpp b/src/Backends/Rendering/Window/Software/X11.cpp
index d715710b..468103dd 100644
--- a/src/Backends/Rendering/Window/Software/X11.cpp
+++ b/src/Backends/Rendering/Window/Software/X11.cpp
@@ -12,7 +12,7 @@ static Window window;
 static XImage* framebufferImage;
 static char* framebufferPixels;
 static int framebufferPitch;
-static char* xfriendlyFB;
+static unsigned char* xfriendlyFB;
 static GC gc;
 static int screenWidth;
 static int screenHeight;
@@ -26,8 +26,9 @@ bool WindowBackend_Software_CreateWindow(const char *window_title, size_t screen
 
     int screen = DefaultScreen(xDisplay);
     Window rootWindow = RootWindow(xDisplay, screen);
-    //window = XCreateWindow(display, rootWindow, 0, 0, screen_width, screen_height, 0, 16, InputOutput, CopyFromParent, 0, NULL);
-    window = XCreateSimpleWindow(xDisplay, rootWindow, 0, 0, screen_width, screen_height, 1, 0, 0);
+
+    window = XCreateWindow(xDisplay, rootWindow, 0, 0, screen_width, screen_height, 0, 24, InputOutput, xVisual, 0, NULL);
+    //window = XCreateSimpleWindow(xDisplay, rootWindow, 0, 0, screen_width, screen_height, 1, 0, 0);
     XSelectInput(xDisplay, window, ExposureMask | KeyPressMask | KeyReleaseMask);
     XMapRaised(xDisplay, window);
     XStoreName(xDisplay, window, window_title);
@@ -45,10 +46,10 @@ bool WindowBackend_Software_CreateWindow(const char *window_title, size_t screen
 
     // Setting up the framebuffer
     framebufferPixels = (char*)malloc(screen_width * screen_height * 3);
-    xfriendlyFB = (char*)malloc(screen_width * screen_height * 4);
-    framebufferImage = XCreateImage(xDisplay, DefaultVisual(xDisplay, DefaultScreen(xDisplay)),
+    xfriendlyFB = (unsigned char*)malloc(screen_width * screen_height * 4);
+    framebufferImage = XCreateImage(xDisplay, xVisual,//DefaultVisual(xDisplay, DefaultScreen(xDisplay)),
                                     depth, ZPixmap, 0,
-                                    xfriendlyFB, screen_width, screen_height,
+                                    (char*)xfriendlyFB, screen_width, screen_height,
                                     32, 0);
     if(framebufferImage == 0) {
         return false;
@@ -76,28 +77,17 @@ void WindowBackend_Software_HandleWindowResize(size_t width, size_t height) {
 }
 
 void WindowBackend_Software_Display(void) {
+    // Convert Cave Story's framebuffer format to the Sun's
+    // This is the exact reverse of how it is on modern
+    // computers. Yup, it's endianess.
     int srci = 0;
-    for(int i = 0; i < screenWidth * screenHeight * 4; i++) {
+    for(int i = 0; i < screenWidth * screenHeight * 4; i += 4) {
         int src;
-        switch(i % 4) {
-            case 0:
-                src = srci + 2;
-                break;
-            case 1:
-                src = srci + 1;
-                break;
-            case 2:
-                src = srci + 0;
-                break;
-            case 3:
-                srci += 3;
-        }
-        xfriendlyFB[i] = framebufferPixels[src];
-        // if(i % 4 != 3) {
-        //     xfriendlyFB[i] = framebufferPixels[srci];
-        //     srci++;
-        // }        
+        xfriendlyFB[i + 0] = 0; // UNUSED
+        xfriendlyFB[i + 1] = framebufferPixels[srci + 2]; // BLUE
+        xfriendlyFB[i + 2] = framebufferPixels[srci + 1]; // GREEN
+        xfriendlyFB[i + 3] = framebufferPixels[srci + 0]; // RED
+        srci += 3;
     }
     XPutImage(xDisplay, window, gc, framebufferImage, 0, 0, 0, 0, screenWidth, screenHeight);
-    //XCopyArea(xDisplay, intermediate, window, gc, 0, 0, screenWidth, screenHeight, 0, 0);
 }