1 files changed, 67 insertions, 0 deletions
diff --git a/transition.py b/transition.py
new file mode 100644
index 0000000..cf2acb4
--- /dev/null
+++ b/transition.py
@@ -0,0 +1,67 @@
+from OpenGL.GL import *
+from OpenGL.GLUT import *
+from OpenGL.GLU import *
+
+class Transition:
+    def draw(self, texture_prev, texture_next, window_width, window_height, delta_time, transition_time, transition_duration):
+        # Update alpha value for fade effect
+        alpha = transition_time / transition_duration
+        if alpha > 1.0:
+            alpha = 1.0
+
+        # Draw the first image
+        self._draw_image(texture_prev, 3840, 2160, window_width, window_height, 1 - alpha)  # TODO instead of decreasing alpha, draw transparent letterboxes
+        # Draw the second image (with transparency)
+        self._draw_image(texture_next, 3840, 2160, window_width, window_height, alpha)
+
+        return alpha >= 1.0  # Complete
+
+
+
+    # Draw the image with blending enabled (to allow fade effect)
+    def _draw_image(self, texture_id, img_width, img_height, window_width, window_height, alpha):
+        if (not alpha): return
+
+        glEnable(GL_BLEND)
+        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
+        glBindTexture(GL_TEXTURE_2D, texture_id)
+        glColor4f(1.0, 1.0, 1.0, alpha)  # Set alpha to control transparency
+
+        # Calculate aspect ratio
+        img_aspect = img_width / float(img_height)
+        win_aspect = window_width / float(window_height)
+
+        scaled_width = window_width
+        scaled_height = window_height
+
+        # Scale the image to fit inside the window while maintaining aspect ratio
+        if img_aspect > win_aspect:
+            # Image is wider than window, letterbox vertically
+            scaled_height = window_width / img_aspect
+        else:
+            # Image is taller than window, letterbox horizontally
+            scaled_width = window_height * img_aspect
+
+        # Position the image so it is centered
+        offset_x = (window_width - scaled_width) / 2
+        offset_y = (window_height - scaled_height) / 2
+
+        # Normalize coordinates to range from -1 to 1
+        x1 = (offset_x / window_width ) * 2 - 1
+        y1 = (offset_y / window_height) * 2 - 1
+        x2 = ((offset_x + scaled_width ) / window_width ) * 2 - 1
+        y2 = ((offset_y + scaled_height) / window_height) * 2 - 1
+
+        # Draw the image in the center with scaling
+        glBegin(GL_QUADS)
+        glTexCoord2f(0, 0)
+        glVertex2f(x1, y1)
+        glTexCoord2f(1, 0)
+        glVertex2f(x2, y1)
+        glTexCoord2f(1, 1)
+        glVertex2f(x2, y2)
+        glTexCoord2f(0, 1)
+        glVertex2f(x1, y2)
+        glEnd()
+
+        glDisable(GL_BLEND)