我试图得到一个简单的三角显示在一个android opengl es 2.0的例子。但什么也没出现，我就是不明白为什么：），我没有错误或什么，只有一个蓝色的屏幕（那是我清晰的颜色）。也许投影矩阵把我的模型放在外面有什么问题？
package dk.madslee.modelviewer;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;
import android.app.Activity;
import android.app.ActivityManager;
import android.content.Context;
import android.content.pm.ConfigurationInfo;
import android.content.res.Resources;
import android.opengl.GLES20;
import android.opengl.GLSurfaceView;
import android.opengl.Matrix;
import android.os.Bundle;
import android.util.Log;
// http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/graphics/GLES20TriangleRenderer.html
public class MainActivity extends Activity
{
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
final Resources resources = getResources();
GLSurfaceView surfaceView = new GLSurfaceView(this);
surfaceView.setEGLContextClientVersion(2); // enable OpenGL 2.0
Log.e("opengl", Boolean.toString(detectOpenGLES20()));
surfaceView.setRenderer(new GLSurfaceView.Renderer()
{
public static final int FLOAT_BYTE_LENGTH = 4;
private int mProgram;
private int mVertexPositionAttributeLocation;
private int mMVMatrixUniformLocation;
private int mPMatrixUniformLocation;
private float[] mMVMatrix = new float[16];
private float[] mPMatrix = new float[16];
private float[] mVertices = {
1.0f, 1.0f, 0.0f,
-1.0f, 1.0f, 0.0f,
1.0f, -1.0f, 0.0f,
};
private FloatBuffer mVertexBuffer;
@Override
public void onSurfaceCreated(GL10 gl, EGLConfig config)
{
mVertexBuffer = ByteBuffer.allocateDirect(mVertices.length * FLOAT_BYTE_LENGTH).order(ByteOrder.nativeOrder()).asFloatBuffer();
mVertexBuffer.put(mVertices);
mVertexBuffer.position(0);
mProgram = createProgram();
mVertexPositionAttributeLocation = GLES20.glGetAttribLocation(mProgram, "aVertexPosition");
mMVMatrixUniformLocation = GLES20.glGetUniformLocation(mProgram, "uMVMatrix");
mPMatrixUniformLocation = GLES20.glGetUniformLocation(mProgram, "mPMatrix");
checkGlError("glGetUniformLocation");
Matrix.setLookAtM(mMVMatrix, 0, 0, 0, -5, 0f, 0f, 0f, 0f, 1.0f, 0.0f);
}
@Override
public void onSurfaceChanged(GL10 gl, int width, int height)
{
GLES20.glViewport(0, 0, width, height);
Matrix.frustumM(mPMatrix, 0, -1, 1, -1, 1, 3, 7); // [UPDATED but didnt solve the problem]
}
@Override
public void onDrawFrame(GL10 gl)
{
GLES20.glClearColor(0, 0, 1.0f, 1.0f);
GLES20.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
GLES20.glUseProgram(mProgram);
checkGlError("glUseProgram");
mVertexBuffer.position(0);
GLES20.glVertexAttribPointer(mVertexPositionAttributeLocation, 3, GLES20.GL_FLOAT, false, 3 * FLOAT_BYTE_LENGTH, mVertexBuffer);
checkGlError("glVertexAttribPointer");
GLES20.glEnableVertexAttribArray(mVertexPositionAttributeLocation);
checkGlError("glEnableVertexAttribArray");
GLES20.glUniformMatrix4fv(mMVMatrixUniformLocation, 1, false, mMVMatrix, 0);
GLES20.glUniformMatrix4fv(mPMatrixUniformLocation, 1, false, mPMatrix, 0);
checkGlError("glUniform4fv");
GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 3);
checkGlError("glDrawArrays");
}
private int createProgram()
{
int program = GLES20.glCreateProgram();
int vertexShader = getShader(GLES20.GL_VERTEX_SHADER, R.string.vertex_shader);
int fragmentShader = getShader(GLES20.GL_FRAGMENT_SHADER, R.string.fragment_shader);
GLES20.glAttachShader(program, vertexShader);
GLES20.glAttachShader(program, fragmentShader);
GLES20.glLinkProgram(program);
GLES20.glUseProgram(program);
return program;
}
private int getShader(int type, int source)
{
int shader = GLES20.glCreateShader(type);
String shaderSource = resources.getString(source);
GLES20.glShaderSource(shader, shaderSource);
GLES20.glCompileShader(shader);
int[] compiled = new int[1];
GLES20.glGetShaderiv(shader, GLES20.GL_COMPILE_STATUS, compiled, 0);
if (compiled[0] == 0)
{
Log.e("opengl", "Could not compile shader");
Log.e("opengl", GLES20.glGetShaderInfoLog(shader));
Log.e("opengl", shaderSource);
}
return shader;
}
private void checkGlError(String op) {
int error;
while ((error = GLES20.glGetError()) != GLES20.GL_NO_ERROR) {
Log.e("opengl", op + ": glError " + error);
throw new RuntimeException(op + ": glError " + error);
}
}
});
setContentView(surfaceView);
}
private boolean detectOpenGLES20() {
ActivityManager am = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
ConfigurationInfo info = am.getDeviceConfigurationInfo();
return (info.reqGlEsVersion >= 0x20000);
}
}
我的阴影是这样的
顶点
attribute vec3 aVertexPosition;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
void main() {
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
}
破片
precision highp float;
void main() {
gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0);
}
最佳答案
请确保禁用背面消隐（按glDisable(GL_CULL_FACE)），因为此时您正在查看几何体的背面，或者尝试在“查看”中使用5而不是-5。实际上默认情况下应该禁用它，但我不确定。
否则它可能是你的投影矩阵。请记住，截头台的参数是通用（3d world）单位，不一定是像素，因此如果不希望世界单位表示像素，则不应采用放入glViewport中的相同值。所以现在你的图像平面是（2*width）x（2*height），你的三角形只占一个像素（实际上，由于透视失真，甚至更少）。尝试类似于Matrix.frustumM(mPMatrix, 0, -1, 1, -1, 1, 3, 7)的方法，或者使用等效于gluPerspective的方法，只需输入所需的视角和窗口的纵横比，这比直接的平截头体参数要自然得多。
编辑：刚发现问题。在glGetUniformLocation中，您编写了mPMatrix而不是uPMatrix，因此您永远无法获得投影矩阵的有效统一位置。奇怪的是，德国劳埃德船级社没有在这个问题上犯错误。