Give the GIF dynamic delay memory to base future delays off of, instead of...

Give the GIF dynamic delay memory to base future delays off of, instead of calculating for the current frame and being jank

src/m_anigif.c

@@ -47,7 +47,8 @@ static RGBA_t *gif_framepalette = NULL;
 
 static FILE *gif_out = NULL;
 static INT32 gif_frames = 0;
-static UINT32 gif_prevframems = 0;
+static UINT32 gif_prevframeus = 0; // "us" is microseconds
+static UINT32 gif_delayus = 0;
 static UINT8 gif_writeover = 0;
 
 
@@ -594,16 +595,20 @@ static void GIF_framewrite(void)
 
 	// screen regions are handled in GIF_lzw
 	{
-		UINT16 delay;
+		UINT16 delay = 0;
 		INT32 startline;
 
 		if (gif_dynamicdelay) {
 			// golden's attempt at creating a "dynamic delay"
-			float delayf = ceil(100.0f/NEWTICRATE);
+			UINT16 mingifdelay = 10; // minimum gif delay in milliseconds (keep at 10 because gifs can't get more precise).
+			gif_delayus += (I_GetTimeMicros() - gif_prevframeus); // increase delay by how much time was spent between last measurement
 
-			delay = (UINT16)((I_GetTimeMicros() - gif_prevframems)/10/1000);
-			if (delay < (int)(delayf))
-				delay = (int)(delayf);
+			if (gif_delayus/1000 >= mingifdelay) // delay is big enough to be able to effect gif frame delay?
+			{
+				int frames = (gif_delayus/1000) / mingifdelay; // get amount of frames to delay.
+				delay = frames; // set the delay to delay that amount of frames.
+				gif_delayus -= frames*(mingifdelay*1000); // remove frames by the amount of milliseconds they take. don't reset to 0, the microseconds help consistency.
+			}
 		}
 		else
 		{
@@ -690,7 +695,7 @@ static void GIF_framewrite(void)
 	}
 	fwrite(gifframe_data, 1, (p - gifframe_data), gif_out);
 	++gif_frames;
-	gif_prevframems = I_GetTimeMicros();
+	gif_prevframeus = I_GetTimeMicros();
 }
 
 
@@ -718,7 +723,8 @@ INT32 GIF_open(const char *filename)
 
 	GIF_headwrite();
 	gif_frames = 0;
-	gif_prevframems = I_GetTimeMicros();
+	gif_prevframeus = I_GetTimeMicros();
+	gif_delayus = 0;
 	return 1;
 }