Effect

public static class GridAnime {
        private static final WeightedRandomPicker<Float> DEGREE_PICKER = new WeightedRandomPicker<>();
        static {
            DEGREE_PICKER.add(0f);
            DEGREE_PICKER.add(90f);
            DEGREE_PICKER.add(180f);
            DEGREE_PICKER.add(270f);
        }
        float maxRadius;
        float duration;
        float elapsed;
        float alphaMult;
        Color color;
        Vector2f loc;
        int index;
        float degree;


        public GridAnime(float maxRadius, float duration, float alphaMult, Color color, Vector2f loc) {
            this.maxRadius = maxRadius;
            this.duration = duration;
            this.alphaMult = alphaMult;
            this.color = color;
            this.loc = new Vector2f(loc);
            this.index = OriMisc.RANDOM.nextInt(2);
            this.degree = DEGREE_PICKER.pick();
        }

        public static void AddNewGridAnime(float maxRadius, float duration, float alphaMult, Color color, Vector2f loc) {
            final RenderMapData data = (RenderMapData) Global.getCombatEngine().getCustomData().get(RENDER_DATA_KEY);
            final List<GridAnime> grids = data.grids;
            grids.add(new GridAnime(maxRadius, duration, alphaMult, color, loc));
        }

        public boolean advance(float amount) {
            elapsed += amount;
            if (elapsed >= duration) {
                elapsed = duration;
                return false;
            }
            return true;
        }

        public void render() {
            float level = Math.min(1f, elapsed / duration);
            float boardRange = maxRadius * 0.1f;
            float size = maxRadius;
            SpriteAPI gridSprite = Global.getSettings().getSprite("fx", "AL_bossgrid_" + index);
            gridSprite.setWidth(size * 2f);
            gridSprite.setHeight(size * 2f);
            gridSprite.setAngle(degree);

            GL11.glColorMask(false, false, false, true);

            GL11.glPushMatrix();
            GL11.glTranslatef(loc.x, loc.y, 0);
            Misc.renderQuadAlpha(0 - size - 1f, 0 - size - 1f, size * 2f + 2f, size * 2f + 2f, Misc.zeroColor, 0f);


            GL11.glDisable(GL11.GL_TEXTURE_2D);
            GL11.glEnable(GL11.GL_BLEND);
            float verts = 60f;

            float radius = level * maxRadius * 0.9f;

            GL11.glBegin(GL11.GL_TRIANGLE_FAN);
            {
                GL11.glColor4f(0, 0, 0f, 0f);
                GL11.glVertex2f(0f, 0f);
                GL11.glColor4f(0f, 0, 0, 1f);
                for (int i = 0; i <= verts; i++) {
                    float rad = (float) (360f / verts * i / 180f * Math.PI);
                    GL11.glVertex2f((float) (radius * FastTrig.cos(rad)), (float) (radius * FastTrig.sin(rad)));
                }
            }
            GL11.glEnd();
            GL11.glBegin(GL11.GL_QUAD_STRIP);
            {
                for (int i = 0; i <= verts; i++) {
                    float rad = (float) (360f / verts * i / 180f * Math.PI);
                    float inRadius = radius - 1f;
                    float outRadius = radius + boardRange;
                    GL11.glColor4f(0f, 0, 0, 1f);
                    GL11.glVertex2f((float) (inRadius * FastTrig.cos(rad)), (float) (inRadius * FastTrig.sin(rad)));
                    GL11.glColor4f(0f, 0, 0, 0f);
                    GL11.glVertex2f((float) (outRadius * FastTrig.cos(rad)), (float) (outRadius * FastTrig.sin(rad)));

                }
            }
            GL11.glEnd();
            gridSprite.setAlphaMult((float) FastTrig.cos(level * 0.5f * Math.PI) * alphaMult);
            gridSprite.setBlendFunc(GL11.GL_DST_ALPHA, GL11.GL_ZERO);
            gridSprite.renderAtCenter(0, 0);

            GL11.glPopMatrix();

            GL11.glColorMask(true, true, true, false);
            gridSprite.setAlphaMult(1f);
            gridSprite.setColor(color);
            gridSprite.setBlendFunc(GL11.GL_DST_ALPHA, GL11.GL_ONE_MINUS_DST_ALPHA);
            gridSprite.renderAtCenter(loc.x, loc.y);
        }
    }