[nostalgia/core] Specify a maximum for priority level

src/nostalgia/modules/core/include/nostalgia/core/gfx.hpp

@@ -23,6 +23,9 @@ struct Sprite {
 	unsigned spriteShape = 0;
 	unsigned spriteSize = 0;
 	unsigned flipX = 0;
+	/**
+	 * Valid priorities: 0-3
+	 */
 	unsigned priority = 0;
 };
 

src/nostalgia/modules/core/src/opengl/gfx.cpp

@@ -113,7 +113,7 @@ static void setSpriteBufferObject(
 	y *= -ymod;
 	x -= 1.f;
 	y += 1.f - ymod;
-	auto const prif = static_cast<float>(priority) * 0.1f;
+	auto const prif = static_cast<float>(priority) * 0.01f;
 	auto const textureRowf = static_cast<float>(textureRow);
 	float const L = flipX ? 1 : 0;
 	float const R = flipX ? 0 : 1;
@@ -416,7 +416,7 @@ static void setSprite(
 				fY,
 				s.tileIdx + i,
 				s.flipX,
-				s.priority,
+				s.priority & 0b11,
 				vbo,
 				ebo);
 		++i;