android - 为什么我们不能画一个像三角形的正方形？

我在android文档中找到了代码。

public class Square {

private FloatBuffer vertexBuffer;
private ShortBuffer drawListBuffer;

// number of coordinates per vertex in this array
static final int COORDS_PER_VERTEX = 3;
static float squareCoords[] = {
        -0.5f,  0.5f, 0.0f,   // top left
        -0.5f, -0.5f, 0.0f,   // bottom left
         0.5f, -0.5f, 0.0f,   // bottom right
         0.5f,  0.5f, 0.0f }; // top right

private short drawOrder[] = { 0, 1, 2, 0, 2, 3 }; // order to draw vertices

public Square() {
    // initialize vertex byte buffer for shape coordinates
    ByteBuffer bb = ByteBuffer.allocateDirect(
    // (# of coordinate values * 4 bytes per float)
            squareCoords.length * 4);
    bb.order(ByteOrder.nativeOrder());
    vertexBuffer = bb.asFloatBuffer();
    vertexBuffer.put(squareCoords);
    vertexBuffer.position(0);

    // initialize byte buffer for the draw list
    ByteBuffer dlb = ByteBuffer.allocateDirect(
    // (# of coordinate values * 2 bytes per short)
            drawOrder.length * 2);
    dlb.order(ByteOrder.nativeOrder());
    drawListBuffer = dlb.asShortBuffer();
    drawListBuffer.put(drawOrder);
    drawListBuffer.position(0);
}

}
为什么我们不能简单地编写以下代码来完成任务？

private short drawOrder[] = {0,1,2,3};

写这篇文章仅仅是为了表现还是唯一的方法？

最佳答案

opengl es不支持将四边形作为原生基元类型；只支持点、线和三角形。