我正在尝试学习OpenGL ES，这是我进军Android开发的一部分。
到目前为止，我已经通过剪切和粘贴我发现的各种教程创建了以下Android应用程序。
该应用程序应该创建2个彩色方块（1个红色方块和1个蓝色方块）并围绕中心点旋转它们。 因此，在旋转的一部分中，红色方块应位于前方，而在旋转的另一部分中，蓝色方块应位于前方。
但是，当我在Android模拟器中运行我的应用程序时，它只显示前面的蓝色方块。
有谁知道我错过了什么？
package hello.world;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.util.ArrayList;
import java.util.List;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;
import android.app.Activity;
import android.content.Context;
import android.opengl.GLSurfaceView;
import android.os.Bundle;
public class HelloActivity extends Activity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new HelloView(this));
}
private class HelloView extends GLSurfaceView {
private HelloRenderer renderer;
public HelloView(Context context) {
super(context);
renderer = new HelloRenderer(context);
setRenderer(renderer);
}
}
private class HelloRenderer implements GLSurfaceView.Renderer {
public float xrot; //X Rotation ( NEW )
public float yrot; //Y Rotation ( NEW )
public float zrot; //Z Rotation ( NEW )
private List<ColoredQuad> quads;
public HelloRenderer(Context context) {
quads = new ArrayList<ColoredQuad>();
quads.add(new ColoredQuad(
new Vertex3D(-1.0f, -1.0f, 1.0f),
new Vertex3D(1.0f, -1.0f, 1.0f),
new Vertex3D(-1.0f, 1.0f, 1.0f),
new Vertex3D(1.0f, 1.0f, 1.0f),
new RGBA(1.0f, 0.0f, 0.0f)));
quads.add(new ColoredQuad(
new Vertex3D(-1.0f, -1.0f, -1.0f),
new Vertex3D(1.0f, -1.0f, -1.0f),
new Vertex3D(-1.0f, 1.0f, -1.0f),
new Vertex3D(1.0f, 1.0f, -1.0f),
new RGBA(0.0f, 0.0f, 1.0f)));
}
/**
* Called whenever drawing is needed.
*/
public void onDrawFrame(GL10 gl) {
// clear screen and depth buffer
gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
gl.glLoadIdentity();
//Drawing
gl.glTranslatef(0.0f, 0.0f, -5.0f); //move 5 units into the screen
gl.glScalef(0.5f, 0.5f, 0.5f); //scale the objects to 50 percent of original size
//Rotate around the axis based on the rotation matrix (rotation, x, y, z)
gl.glRotatef(xrot, 1.0f, 0.0f, 0.0f); //X
gl.glRotatef(yrot, 0.0f, 1.0f, 0.0f); //Y
gl.glRotatef(zrot, 0.0f, 0.0f, 1.0f); //Z
for (ColoredQuad quad : quads) {
quad.draw(gl);
}
//Change rotation factors (nice rotation)
xrot += 3.0f;
yrot += 2.0f;
zrot += 1.0f;
}
/**
* Called when the surface has changed.
* For example, when switching from portrait to landscape view.
*/
public void onSurfaceChanged(GL10 gl, int width, int height) {
gl.glViewport(0, 0, width, height);
}
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
gl.glEnable(GL10.GL_SMOOTH); // enable smooth shading
gl.glClearColor(0.0f, 0.0f, 0.0f, 0.5f); // black background
gl.glClearDepthf(GL10.GL_DEPTH_TEST); // enable depth testing
gl.glDepthFunc(GL10.GL_LEQUAL); // type of depth testing to do
//Really Nice Perspective Calculations
gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST);
}
}
private class Vertex3D {
public float x;
public float y;
public float z;
public Vertex3D(float x, float y, float z) {
this.x = x;
this.y = y;
this.z = z;
}
}
public class RGBA {
public float red;
public float blue;
public float green;
public float alpha;
public RGBA(float red, float green, float blue) {
this.red = red;
this.blue = blue;
this.green = green;
this.alpha = 1.0f;
}
}
private ByteBuffer makeByteBuffer(byte[] array)
{
ByteBuffer bb = ByteBuffer.allocateDirect(array.length);
bb.put(array);
bb.position(0);
return bb;
}
private FloatBuffer makeFloatBuffer(float[] array)
{
ByteBuffer bb = ByteBuffer.allocateDirect(array.length * 4);
bb.order(ByteOrder.nativeOrder());
FloatBuffer fb = bb.asFloatBuffer();
fb.put(array);
fb.position(0);
return fb;
}
private class ColoredQuad {
private FloatBuffer vertexBuffer;
private FloatBuffer colorBuffer;
private ByteBuffer indexBuffer;
private float[] vertices = new float[12]; // 4 vertices * XYZ (12)
private float[] colors = new float[16]; // 4 vertices * RGBA (16)
private byte[] indices = {
0, 1, 2, 1, 2, 3
};
public ColoredQuad(Vertex3D bottomLeft, Vertex3D bottomRight, Vertex3D topLeft, Vertex3D topRight, RGBA color) {
vertices[0] = bottomLeft.x; vertices[1] = bottomLeft.y; vertices[2] = bottomLeft.z;
vertices[3] = bottomRight.x; vertices[4] = bottomRight.y; vertices[5] = bottomRight.z;
vertices[6] = topLeft.x; vertices[7] = topLeft.y; vertices[8] = topLeft.z;
vertices[9] = topRight.x; vertices[10]= topRight.y; vertices[11]= topRight.z;
colors[0] = color.red; colors[1] = color.green; colors[2] = color.blue; colors[3] = color.alpha;
colors[4] = color.red; colors[5] = color.green; colors[6] = color.blue; colors[7] = color.alpha;
colors[8] = color.red; colors[9] = color.green; colors[10]= color.blue; colors[11]= color.alpha;
colors[12]= color.red; colors[13]= color.green; colors[14]= color.blue; colors[15]= color.alpha;
vertexBuffer = makeFloatBuffer(vertices);
colorBuffer = makeFloatBuffer(colors);
indexBuffer = makeByteBuffer(indices);
}
public void draw(GL10 gl) {
//Point to our buffers
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
gl.glEnableClientState(GL10.GL_COLOR_ARRAY);
//Set the face rotation
gl.glFrontFace(GL10.GL_CCW);
//Enable the vertex and texture state
gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer);
gl.glColorPointer(4, GL10.GL_FLOAT, 0, colorBuffer);
//Draw the vertices as triangles, based on the Index Buffer information
gl.glDrawElements(GL10.GL_TRIANGLES, indices.length, GL10.GL_UNSIGNED_BYTE, indexBuffer);
//Disable the client state before leaving
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
}
}
}
答案 0 :(得分：1)
你只看到前面的蓝色的原因是因为深度测试出了问题，而蓝色的那个只是最后绘制（超过其他所有）。
你说的地方
gl.glClearDepthf(GL10.GL_DEPTH_TEST); // enable depth testing
gl.glEnable(GL10.GL_DEPTH_TEST);
可能
gl.glClearDepthf(1.0f);
但无论如何这都是默认值。
干杯，阿尔特。