ı尝试绘制一个正方形..但是当ı运行代码时,ı看到一个tringle,而不是一个正方形... :))这里有什么问题?
public class MyGL20Renderer implements GLSurfaceView.Renderer {
private FloatBuffer square1;
private void initShapes(){
float square1Coords[]={
-0.5f, -0.5f, 0.0f, // 0. left-bottom
0.5f, -0.5f, 0.0f, // 1. right-bottom
0.0f, 0.0f, 0.0f, // 2. left-top
0.5f, 0.5f, 0.0f // 3. right-top
};
// initialize vertex Buffer for square
ByteBuffer vbb4 = ByteBuffer.allocateDirect(
// (# of coordinate values * 4 bytes per float)
square1Coords.length * 4);
vbb4.order(ByteOrder.nativeOrder());
square1 = vbb4.asFloatBuffer();
square1.put(square1Coords);
square1.position(0);
}
。 。 。
public void onDrawFrame(GL10 gl) {
// Redraw background color
gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
// Draw the square
gl.glColor4f(0.0f, 0.0f, 1.0f, 0.0f); //blue
gl.glVertexPointer(3, GL10.GL_FLOAT, 0, square1);
gl.glDrawArrays(GL10.GL_TRIANGLES, 0, 4);
}
答案 0 :(得分:2)
您指定GL_TRIANGLES
,但只有四个顶点。试试六。
或使用GL_TRIANGLE_STRIP
。
答案 1 :(得分:1)
左上角似乎是错误的,应该是-0.5, 0.5, 0.0
我同意genpfault认为你应该使用GL_TRIANGLE_STRIP
答案 2 :(得分:0)
好..我找到了解决问题的方法,ı想..
//this is our Square class
public class Square {
private FloatBuffer vertexBuffer; // buffer holding the vertices
private float vertices[] = {
-0.3f, -0.3f, 0.0f, // 0. left-bottom
0.3f, -0.3f, 0.0f, // 1. right-bottom
-0.3f, 0.3f, 0.0f, // 2. left-top
0.3f, 0.3f, 0.0f // 3. right-top
};
public Square() {
// a float has 4 bytes so we allocate for each coordinate 4 bytes
ByteBuffer vertexByteBuffer = ByteBuffer.allocateDirect(vertices.length * 4);
vertexByteBuffer.order(ByteOrder.nativeOrder());
// allocates the memory from the byte buffer
vertexBuffer = vertexByteBuffer.asFloatBuffer();
// fill the vertexBuffer with the vertices
vertexBuffer.put(vertices);
// set the cursor position to the beginning of the buffer
vertexBuffer.position(0);
}
/** The draw method for the square with the GL context */
public void draw(javax.microedition.khronos.opengles.GL10 gl) {
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
// set the colour for the square
gl.glColor4f(1.0f, 0.0f, 0.0f, 0.0f); //red
// Point to our vertex buffer
gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer);
// Draw the vertices as triangle strip
gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, vertices.length / 3);
//Disable the client state before leaving
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
}
}
// and this is our renderer class
public class MyRenderer implements GLSurfaceView.Renderer {
// the square to be drawn
private Square square;
public MyRenderer() {
this.square = new Square();
@Override
public void onDrawFrame(GL10 gl) {
// clear Screen and Depth Buffer
gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
// Reset the Modelview Matrix
gl.glLoadIdentity();
// Drawing
gl.glTranslatef(0.0f, 0.0f, -5.0f);
// Draw the square
square.draw(gl);
}
@Override
public void onSurfaceChanged(GL10 gl, int width, int height) {
if(height == 0) { //Prevent A Divide By Zero By
height = 1; //Making Height Equal One
}
gl.glViewport(0, 0, width, height); //Reset The Current Viewport
gl.glMatrixMode(GL10.GL_PROJECTION); //Select The Projection Matrix
gl.glLoadIdentity(); //Reset The Projection Matrix
//Calculate The Aspect Ratio Of The Window
GLU.gluPerspective(gl, 45.0f, (float)width / (float)height, 0.1f, 100.0f);
gl.glMatrixMode(GL10.GL_MODELVIEW); //Select The Modelview Matrix
gl.glLoadIdentity(); //Reset The Modelview Matrix
}
@Override
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
}
}