Hello! How can you detect if a player is looking at the sun/moon?

The short answer is you probably can't in general because it will depend on if/how mods modify the sky rendering.

 

Assuming vanilla rendering, try this which (I think?) shows the player's view vector and a calculation of the vector to the sun at the top of the screen.

@Mod.EventBusSubscriber(modid = MODID, bus = Bus.MOD, value = Dist.CLIENT)
public class ModClientEvents {

    @SubscribeEvent
    public static void registerOverlay(RegisterGuiOverlaysEvent event) {

        event.registerAboveAll("view_sun", (gui, poseStack, partialTick, screenWidth, screenHeight) -> {

            Minecraft minecraft = Minecraft.getInstance();
            Entity entity = minecraft.cameraEntity;
            Level level = minecraft.level;
            float sunAngle = level.getSunAngle(partialTick) + (float) Math.PI / 2; // use -pi/2 for the moon
            Vec3 view = entity.getViewVector(1.0f);
            Vec3 sun = new Vec3(Math.cos(sunAngle), Math.sin(sunAngle), 0f);
            String msg = String.format(Locale.ROOT, "%.3f / %.3f / %.3f / %.3f / %.3f / %.3f / %.3f", sunAngle, view.x, view.y, view.z, sun.x, sun.y, sun.z);

            gui.setupOverlayRenderState(true, false, null);
            Font font = minecraft.font;
            GuiComponent.fill(poseStack, 1, 1, 3 + font.width(msg), 1 + font.lineHeight, 0x6FAFAFB0);
            font.draw(poseStack, msg, 2, 2, 0xE0E0E0);
        });
    }
}

 

You can probably use this as a starting point of your calculation to see if the 2 vector's components are close in value, or maybe something more complicated (e.g. taking into account moon phases).

I would guess you also want to do some kind of ray trace - entity.pick() - to see if there is a block/fluid or entity blocking the sun, and also check the weather. 🙂
 

Edited August 30, 20223 yr by warjort