AK: fmod(), sin(), cos(), atan2() for non-x86

[nico]

atan2() is implemented in terms of atan(), so the implementation isn't super useful yet.

[nico]

With this local diff:

local patch to Gradient

diff --git a/Userland/Demos/Gradient/Gradient.cpp b/Userland/Demos/Gradient/Gradient.cpp
index 56168c6057b..b29ec23e38d 100644
--- a/Userland/Demos/Gradient/Gradient.cpp
+++ b/Userland/Demos/Gradient/Gradient.cpp
@@ -12,6 +12,7 @@
 #include <LibGUI/Painter.h>
 #include <LibGUI/Window.h>
 #include <LibGfx/Bitmap.h>
+#include <LibGfx/Path.h>
 #include <LibMain/Main.h>
 #include <stdio.h>
 #include <time.h>
@@ -83,6 +84,35 @@ void Gradient::draw()
         m_bitmap->rect(),
         colors[start_color_index],
         colors[end_color_index]);
+
+    //Gfx::Path p1, p2;
+    int last_x, last_y1, last_y2;
+    for (int x = 0; x < m_bitmap->width(); ++x) {
+        float fx = x / (float)m_bitmap->width();
+        fx = (fx - 0.5f) * 4 * 2 * AK::Pi<float>;
+        float fy1 = sin(fx);
+        float fy2 = cos(fx);
+
+        int y1 = m_bitmap->height() / 2 * (1 - 0.5f * 0.4f * fy1);
+        int y2 = m_bitmap->height() / 2 * (1 - 0.5f * 0.7f * fy2);
+
+        if (x == 0) {
+            //p1.move_to({ x, y1 });
+            //p2.move_to({ x, y2 });
+        } else {
+            //p1.line_to({ x, y1 });
+            //p2.line_to({ x, y2 });
+
+           painter.draw_line({ last_x, last_y1 }, { x, y1 }, Gfx::Color::Red);
+           painter.draw_line({ last_x, last_y2 }, { x, y2 }, Gfx::Color::Green);
+        }
+        last_x = x;
+        last_y1 = y1;
+        last_y2 = y2;
+    }
+
+    //painter.stroke_path(p1, Gfx::Color::Red, 3);
+    //painter.stroke_path(p2, Gfx::Color::Green, 3);
 }
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
@@ -97,7 +127,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto window = TRY(Desktop::Screensaver::create_window("Gradient"sv, "app-gradient"sv));
 
-    auto gradient_widget = window->set_main_widget<Gradient>(64, 48, 10000);
+    auto gradient_widget = window->set_main_widget<Gradient>(640, 480, 10000);
     gradient_widget->set_fill_with_background_color(false);
     gradient_widget->set_override_cursor(Gfx::StandardCursor::Hidden);
     gradient_widget->update();

Before:

After the "Make periodic" commit:

After the "a bit better" commit:

[nico]

More screenshots!

Before:

After "Make periodic":

After "a bit better":

After atan2:

Build/lagom/bin/pdf in lagom still renders it fine (it now uses the new atan2 which calls local libc atan):

[nico]

Huh, looks like you're right! Are the macOS lagom bots running on arm machines? Must be, I suppose?

[ADKaster]

Yeah GitHub has a load of racks of re-housed mac minis they use for the macOS free tier

[nico]

Locally, it seems removing the sin/cos libcall is at fault. I put those back, let's see what CI says.

[nico]

css-gradients.png was different with the atan2 change. (From manually eyeing the diff, in harmless ways, but I didn't expect the atan2 change to change behavior at all, so I want to investigate that a bit.) I put back the libcalls for both atan2 and fmod for now since replacing the non-serenity codepath isn't the main thrust of this PR. I still want to do this in a future PR, but it doesn't have to be in here.