Question

我正在将C ++ Point和Polygons绘制到Android.Initially它直接将代码移植到java风格。我可以使用下面的代码绘制点。

//POINT
public class MyPoint
{

 public float x,y,z;

}
//Points in x,y,z format are parsed and stored here
public static ArrayList<MyPoint> m_vPoints;


public static  float [] fPointVertices ={};//Float array
public static FloatBuffer mPointVerticesFloatBuffer;//Buffer for rendering

int m_drawCount=0;

//Converting to float array
//AND
//Converting to FloatBuffer
public  static void FormatPointDataAsGLBuffer()
{
        fPointVertices=new float[m_vPoints.size()*3];
        int count=0;

        for(int i=0;i<m_vPoints.size();i++)
        {
            fPointVertices[count]=m_vPoints.get(i).x;
            fPointVertices[count+1]=0.0f;
            fPointVertices[count+2]=m_vPoints.get(i).y;
            count=count+3;
        }

        m_drawCount=count;
        //Convert vertices to OpenGL ES compatible format
        mPointVerticesFloatBuffer= ByteBuffer.allocateDirect(fPointVertices.length * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
        mPointVerticesFloatBuffer.put(fPointVertices).position(0);
}

public void DrawPoints()
{
    GLES20.glEnableVertexAttribArray(mPositionHandle);
    GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, 0, mPointVerticesFloatBuffer);
    GLES20.glDrawArrays(GLES20.GL_POINTS, 0, m_drawCount);
    GLES20.glDisableVertexAttribArray(mPositionHandle);

}

我还不确定如何使用单个float数组绘制多边形。但是在C ++版本中，使用glBufferSubData创建VBO并使用单个调用glMultiDrawArrays，如下面的SE查询中所述。 Using VBO to draw line string

多边形相关脚本如下所示

//POLYGON

public static ArrayList<MyPolygon> m_vPolygons;
public static class MyPolygon
    {
        public ArrayList<MyPoint> vPointList;
    }


public  static void FormatPolygonDataAsGLBuffer()
    {
        for(int i=0;i<vPolygons.size();i++)
        {

            for(int j=0;j<vPolygons.get(i).vPointList.size();j++)
            {
                fPointVertices[count]=vPolygons.get(i).vPointList.get(i).x;
                fPointVertices[count+1]=0.0f;
                fPointVertices[count+2]=-vPolygons.get(i).vPointList.get(i).y;//Negating since y is outwards from the screen and z is upwards
                count=count+3;
            }

        }   
    }


    public void DrawPolygons()
    {
        //WHAT IS THE RIGHT WAY HERE???
        //glBufferSubData
        //Draw the lines
        //glMultiDrawArrays(GLES20.GL_LINE_LOOP, startIndices,endIndices,nPolygonCount); 
    }

Answer 1

glBufferSubData功能仍然存在，因此应该仍然像以前一样工作。 GLES中不存在glMultiDrawArrays函数，因此您只需要对glDrawArrays()进行多次单独调用，每个对象都要渲染一次。

在OpenGL ES Android中使用glBufferSubData和glMultiDrawArrays

1 个答案: