xiaozhuai · December 18, 2024 08:46 · Dec 18, 2024 · Dec 18, 2024 · Dec 18, 2024
diff --git a/x11_art.c b/x11_art.c
@@ -10,7 +10,6 @@
 
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
-
 #include <stdlib.h>
 #include <time.h>
 #include <math.h>

diff --git a/x11_art.c b/x11_art.c
@@ -0,0 +1,127 @@
+/**
+ * 
+ * Compile on Linux with:
+ * gcc x11_art.c -o x11_art -O3 -lX11
+ *
+ * Compile on MacOS with:
+ * gcc x11_art.c -o x11_art -O3 -lX11 -I/opt/X11/include -L/opt/X11/lib
+ *
+ */
+
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+
+#include <stdlib.h>
+#include <time.h>
+#include <math.h>
+#include <stdio.h>
+
+float length(const float *v) {
+    return sqrt(v[0] * v[0] + v[1] * v[1]);
+}
+
+int clamp(int x, int min, int max) {
+    return x < min ? min : x > max ? max : x;
+}
+
+float fract(float x) {
+    return x - floor(x);
+}
+
+void palette(float t, float *color) {
+    float a[3] = {0.5, 0.5, 0.5};
+    float b[3] = {0.5, 0.5, 0.5};
+    float c[3] = {1.0, 1.0, 1.0};
+    float d[3] = {0.263, 0.416, 0.557};
+    for (int i = 0; i < 3; ++i) {
+        color[i] = a[i] + b[i] * cos(6.28318 * (c[i] * t + d[i]));
+    }
+}
+
+unsigned long fragment(int x, int y, int width, int height, float time) {
+    float uv[2];
+    float uv0[2];
+    uv[0] = uv0[0] = (2.0 * x - width) / height;
+    uv[1] = uv0[1] = (2.0 * y - height) / height;
+    float color[3] = {0.0, 0.0, 0.0};
+    for (int i = 0; i < 4; ++i) {
+        uv[0] = fract(uv[0] * 1.5) - 0.5;
+        uv[1] = fract(uv[1] * 1.5) - 0.5;
+        float d = length(uv) * exp(-length(uv0));
+        float col[3];
+        palette(length(uv0) + i * 0.4 + time * 0.4, col);
+        d = sin(d * 8.0 + time) / 8.0;
+        d = fabs(d);
+        d = pow(0.01 / d, 1.2);
+        for (int j = 0; j < 3; ++j) {
+            color[j] += col[j] * d;
+        }   
+    }
+    unsigned char color_u8c4[4] = {
+        clamp(color[2] * 255, 0, 255),
+        clamp(color[1] * 255, 0, 255),
+        clamp(color[0] * 255, 0, 255),
+        255
+    };
+    return *(unsigned long *)color_u8c4;
+}
+
+float now() {
+    struct timespec ts;
+    clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts);
+    return ts.tv_sec + ts.tv_nsec / 1000000000.0;
+}
+
+int main() {
+    const int width = 800;
+    const int height = 600;
+    Display *d = XOpenDisplay(NULL);
+    Window w = XCreateSimpleWindow(
+        d, RootWindow(d, 0), 
+        10, 10, width, height, 1, 0, 0
+    );
+    XSizeHints hints;
+    hints.flags = PMinSize | PMaxSize;
+    hints.min_width = hints.max_width = width;
+    hints.min_height = hints.max_height = height;
+    XSetWMNormalHints(d, w, &hints);
+    Atom wmDeleteWindow = XInternAtom(d, "WM_DELETE_WINDOW", False);
+    XSetWMProtocols(d, w, &wmDeleteWindow, 1);
+    XImage *img = XCreateImage(
+        d, DefaultVisual(d, 0), DefaultDepth(d, 0), 
+        ZPixmap, 0, 
+        malloc(width * height * 4), 
+        width, height, 32, 0
+    );
+    XMapWindow(d, w);
+    XFlush(d);
+    XEvent e;
+    int running = 1;
+    const float start = now();
+    while(running) {
+        while(XPending(d)) {
+            XNextEvent(d, &e);
+            if (e.type == ClientMessage) {
+                if ((Atom)e.xclient.data.l[0] == wmDeleteWindow) {
+                    running = 0;
+                    break;
+                }
+            }
+        }
+        if (!running) break;
+        const float time = now() - start;
+        // printf("time: %f\n", time);
+        for (int y = 0; y < height; y++) {
+            for (int x = 0; x < width; x++) {
+                unsigned long color = fragment(x, y, width, height, time);
+                XPutPixel(img, x, y, color);
+            }
+        }
+        XPutImage(d, w, DefaultGC(d, 0), img, 0, 0, 0, 0, width, height);
+        XFlush(d);
+    }
+    XDestroyImage(img);
+    XDestroyWindow(d, w);
+    XCloseDisplay(d);
+    return 0;
+}
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