Vector2 vpos = new Vector2(rand.Next(960-size),rand.Next(544-size));
Vector2 vsize = new Vector2(size,size);
Vector2 tcoord = new Vector2(0.0f,0.0f);
Vector2 tsize = new Vector2(32.0f,32.0f);
Vector4 vrgba = new Vector4(1.0f,1.0f,1.0f,1.0f);
shader_.SetUniformValue(4+1, ref vpos);
shader_.SetUniformValue(4+2, ref vsize);
shader_.SetUniformValue(4+3, ref vrgba);
shader_.SetUniformValue(4+4, ref tcoord);
shader_.SetUniformValue(4+5, ref tsize);
graphics_.DrawArrays(DrawMode.TriangleStrip,0,4,N);

uniformでパラメータを指定する方法だと
8x8のスプライトが300個で処理落ちが始まって遅いっす