synced from DRGTK 1.27

2 files changed, 76 insertions, 0 deletions

diff --git a/samples/12_c_extensions/03_native_pixel_arrays/app/ext.c b/samples/12_c_extensions/03_native_pixel_arrays/app/ext.c
new file mode 100644
index 0000000..49d0e40
--- /dev/null
+++ b/samples/12_c_extensions/03_native_pixel_arrays/app/ext.c
@@ -0,0 +1,54 @@
+#ifndef NULL
+#define NULL 0
+#endif
+typedef unsigned int Uint32;
+
+extern void *(*drb_symbol_lookup)(const char *sym);
+typedef void (*drb_upload_pixel_array_fn)(const char *name, const int w, const int h, const Uint32 *pixels);
+
+void update_scanner_texture(void)
+{
+    #define dimension 10
+
+    static drb_upload_pixel_array_fn drb_upload_pixel_array = NULL;
+    static int pos = 0;
+    static int posinc = 1;
+
+    if (!drb_upload_pixel_array) {
+        drb_upload_pixel_array = drb_symbol_lookup("drb_upload_pixel_array");
+        if (!drb_upload_pixel_array) {
+            return;  // oh well.
+        }
+    }
+
+
+    // Set up our "scanner" pixel array and fill it with black pixels.
+
+    // You could make this faster by making this array static (which will
+    //  initialize it all to zero at startup), and then blanking the previous
+    //  line and drawing the next, and not touching the rest.
+    Uint32 pixels[dimension * dimension];
+    for (int i = 0; i < (dimension * dimension); i++) {
+        pixels[i] = 0xFF000000;  // full alpha, full black
+    }
+
+    // Draw a green line that bounces up and down the sprite.
+    Uint32 *line = pixels + (pos * dimension);
+    for (int i = 0; i < dimension; i++) {
+        line[i] = 0xFF00FF00;   // full alpha, full green
+    }
+
+    // Adjust position for next frame.
+    pos += posinc;
+    if ((posinc > 0) && (pos >= dimension)) {
+        posinc = -1;
+        pos = dimension - 1;
+    } else if ((posinc < 0) && (pos < 0)) {
+        posinc = 1;
+        pos = 1;
+    }
+
+    // Send it to the renderer to create/update a sprite.
+    drb_upload_pixel_array("scanner", dimension, dimension, pixels);
+}
+
diff --git a/samples/12_c_extensions/03_native_pixel_arrays/app/main.rb b/samples/12_c_extensions/03_native_pixel_arrays/app/main.rb
new file mode 100644
index 0000000..1dbc716
--- /dev/null
+++ b/samples/12_c_extensions/03_native_pixel_arrays/app/main.rb
@@ -0,0 +1,22 @@
+$gtk.ffi_misc.gtk_dlopen("ext")
+include FFI::CExt
+
+def tick args
+  args.state.rotation ||= 0
+
+  update_scanner_texture   # this calls into a C extension!
+
+  # New/changed pixel arrays get uploaded to the GPU before we render
+  #  anything. At that point, they can be scaled, rotated, and otherwise
+  #  used like any other sprite.
+  w = 100
+  h = 100
+  x = (1280 - w) / 2
+  y = (720 - h) / 2
+  args.outputs.background_color = [64, 0, 128]
+  args.outputs.primitives << [x, y, w, h, :scanner, args.state.rotation].sprite
+  args.state.rotation += 1
+
+  args.outputs.primitives << args.gtk.current_framerate_primitives
+end
+