我正在尝试深入学习Android中的OpenGLES 2.0。我试图在屏幕的中心绘制一个简单点，但不知何故，这一点没有显示出来。
public class MyRenderer implements GLSurfaceView.Renderer {
Context context;
private int mProgram;
private final float[] mViewMatrix=new float[16];
private float[] mProjectionMatrix=new float[16];
private final float[] mPointModelMatrix=new float[16];
private final float[] mMVPMatrix=new float[16];
private final float[] mPointPosInModelSpace = new float[] {0.0f, 0.0f, 0.0f, 1.0f};
private final float[] mPointPosInWorldSpace = new float[4];
private final float[] mPointPosInEyeSpace = new float[4];
private int pointMVPMatrixHandle;
private int pointPositionHandle;
public MyRenderer(Context context){
this.context=context;
}
public void onDrawFrame(GL10 arg0) {
// TODO Auto-generated method stub
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
Matrix.setIdentityM(mPointModelMatrix, 0);
Matrix.translateM(mPointModelMatrix, 0, 0.0f, 0.0f, -3.0f);
Matrix.multiplyMV(mPointPosInWorldSpace, 0, mPointModelMatrix, 0, mPointPosInModelSpace, 0);
Matrix.multiplyMV(mPointPosInEyeSpace, 0, mViewMatrix, 0, mPointPosInWorldSpace, 0);
GLES20.glUseProgram(mProgram);
drawPoint();
}
private void drawPoint(){
pointMVPMatrixHandle=GLES20.glGetUniformLocation(mProgram, "u_MVPMatrix");
pointPositionHandle=GLES20.glGetAttribLocation(mProgram, "a_position");
GLES20.glVertexAttrib3f(pointPositionHandle, mPointPosInEyeSpace[0], mPointPosInEyeSpace[1], mPointPosInEyeSpace[2]);
GLES20.glDisableVertexAttribArray(pointPositionHandle);
Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, mPointModelMatrix, 0);
Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0);
GLES20.glUniformMatrix4fv(pointMVPMatrixHandle, 1, false, mMVPMatrix, 0);
// Draw the point.
GLES20.glDrawArrays(GLES20.GL_POINTS, 0, 1);
}
public void onSurfaceChanged(GL10 gl, int width, int height) {
// TODO Auto-generated method stub
GLES20.glViewport(0, 0, width, height);
final float ratio=(float)width/height;
Log.d("Ratio is", " "+ratio);
Log.d("Width is"," "+width+" and "+height);
final float left = -ratio;
final float right = ratio;
final float bottom= -1.0f;
final float top = 1.0f;
final float near = 1.0f;
final float far = 10.0f;
Matrix.frustumM(mProjectionMatrix, 0, left, right, bottom, top, near, far);
}
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
// TODO Auto-generated method stub
GLES20.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
GLES20.glEnable(GLES20.GL_CULL_FACE);
GLES20.glEnable(GLES20.GL_DEPTH_TEST);
float eyeX=0.0f;
float eyeY=0.0f;
float eyeZ=-0.5f;
float centerX=0.0f;
float centerY=0.0f;
float centerZ=-5.0f;
float upX=0.0f;
float upY=1.0f;
float upZ=0.0f;
Matrix.setLookAtM(mViewMatrix, 0, eyeX, eyeY, eyeZ, centerX, centerY, centerZ, upX, upY, upZ);
final String vertexShader=this.getVertexShader();
final String fragmentShader=this.getFragmentShader();
final int vertexShaderHandle=ShaderHelper.compileShader(GLES20.GL_VERTEX_SHADER, vertexShader);
final int fragmentShaderHandle=ShaderHelper.compileShader(GLES20.GL_FRAGMENT_SHADER, fragmentShader);
mProgram=ShaderHelper.createAndLinkProgram(vertexShaderHandle, fragmentShaderHandle, new String[]{"a_position"});
}
private String getVertexShader(){
final String vertexShader="uniform mat4 u_MVPMatrix; \n"
+ "attribute vec4 a_Position; \n"
+ "void main() \n"
+ "{ \n"
+ " gl_Position = u_MVPMatrix \n"
+ " * a_Position; \n"
+ " gl_PointSize = 10.0; \n"
+ "} \n";
return vertexShader;
}
private String getFragmentShader(){
final String fragmentShader="precision mediump float; \n"
+ "void main() \n"
+ "{ \n"
+ " gl_FragColor = vec4(1.0, \n"
+ " 1.0, 1.0, 1.0); \n"
+ "} \n";
return fragmentShader;
}
}
我非常确定我指向双眼并指向负Z方向（远离观察者）。该点应显示为顶点着色器，点大小为10.0但不知何故，没有运气。
注意：ShaderHelper是一个带有静态方法compileShader和createAndLinkProgram的类，其中用于编译着色器，检查错误的代码被写入。 （程序中没有错误）
答案 0 :(得分：3)
这是我根据您的代码构建的用于显示点的类。由于最终可能会使用多个点，因此最好将点推入顶点数组中，如图所示。
package point.example.point;
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.opengl.GLES20;
import android.opengl.GLSurfaceView;
import android.opengl.Matrix;
public class PointRenderer implements GLSurfaceView.Renderer
{
private float[] mModelMatrix = new float[16];
private float[] mViewMatrix = new float[16];
private float[] mProjectionMatrix = new float[16];
private float[] mMVPMatrix = new float[16];
private int mMVPMatrixHandle;
private int mPositionHandle;
float[] vertices = {
0.0f,0.0f,0.0f
};
FloatBuffer vertexBuf;
@Override
public void onSurfaceCreated(GL10 glUnused, EGLConfig config)
{
vertexBuf = ByteBuffer.allocateDirect(vertices.length * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
vertexBuf.put(vertices).position(0);
// Set the background clear color to gray.
GLES20.glClearColor(0.5f, 0.5f, 0.5f, 0.5f);
float eyeX=0.0f;
float eyeY=0.0f;
float eyeZ=0.0f;
float centerX=0.0f;
float centerY=0.0f;
float centerZ=-5.0f;
float upX=0.0f;
float upY=1.0f;
float upZ=0.0f;
// Set the view matrix. This matrix can be said to represent the camera position.
// NOTE: In OpenGL 1, a ModelView matrix is used, which is a combination of a model and
// view matrix. In OpenGL 2, we can keep track of these matrices separately if we choose.
Matrix.setLookAtM(mViewMatrix, 0, eyeX, eyeY, eyeZ, centerX, centerY, centerZ, upX, upY, upZ);
final String vertexShader =
"uniform mat4 u_MVPMatrix; \n"
+ "attribute vec4 a_Position; \n"
+ "void main() \n"
+ "{ \n"
+ " gl_Position = u_MVPMatrix \n"
+ " * a_Position; \n"
+ " gl_PointSize = 10.0; \n"
+ "} \n";
final String fragmentShader =
"precision mediump float; \n"
+ "void main() \n"
+ "{ \n"
+ " gl_FragColor = vec4(1.0, \n"
+ " 1.0, 1.0, 1.0); \n"
+ "} \n";
// Load in the vertex shader.
int vertexShaderHandle = GLES20.glCreateShader(GLES20.GL_VERTEX_SHADER);
if (vertexShaderHandle != 0)
{
// Pass in the shader source.
GLES20.glShaderSource(vertexShaderHandle, vertexShader);
// Compile the shader.
GLES20.glCompileShader(vertexShaderHandle);
// Get the compilation status.
final int[] compileStatus = new int[1];
GLES20.glGetShaderiv(vertexShaderHandle, GLES20.GL_COMPILE_STATUS, compileStatus, 0);
// If the compilation failed, delete the shader.
if (compileStatus[0] == 0)
{
GLES20.glDeleteShader(vertexShaderHandle);
vertexShaderHandle = 0;
}
}
if (vertexShaderHandle == 0)
{
throw new RuntimeException("Error creating vertex shader.");
}
// Load in the fragment shader shader.
int fragmentShaderHandle = GLES20.glCreateShader(GLES20.GL_FRAGMENT_SHADER);
if (fragmentShaderHandle != 0)
{
// Pass in the shader source.
GLES20.glShaderSource(fragmentShaderHandle, fragmentShader);
// Compile the shader.
GLES20.glCompileShader(fragmentShaderHandle);
// Get the compilation status.
final int[] compileStatus = new int[1];
GLES20.glGetShaderiv(fragmentShaderHandle, GLES20.GL_COMPILE_STATUS, compileStatus, 0);
// If the compilation failed, delete the shader.
if (compileStatus[0] == 0)
{
GLES20.glDeleteShader(fragmentShaderHandle);
fragmentShaderHandle = 0;
}
}
if (fragmentShaderHandle == 0)
{
throw new RuntimeException("Error creating fragment shader.");
}
// Create a program object and store the handle to it.
int programHandle = GLES20.glCreateProgram();
if (programHandle != 0)
{
// Bind the vertex shader to the program.
GLES20.glAttachShader(programHandle, vertexShaderHandle);
// Bind the fragment shader to the program.
GLES20.glAttachShader(programHandle, fragmentShaderHandle);
// Bind attributes
GLES20.glBindAttribLocation(programHandle, 0, "a_Position");
// Link the two shaders together into a program.
GLES20.glLinkProgram(programHandle);
// Get the link status.
final int[] linkStatus = new int[1];
GLES20.glGetProgramiv(programHandle, GLES20.GL_LINK_STATUS, linkStatus, 0);
// If the link failed, delete the program.
if (linkStatus[0] == 0)
{
GLES20.glDeleteProgram(programHandle);
programHandle = 0;
}
}
if (programHandle == 0)
{
throw new RuntimeException("Error creating program.");
}
// Set program handles. These will later be used to pass in values to the program.
mMVPMatrixHandle = GLES20.glGetUniformLocation(programHandle, "u_MVPMatrix");
mPositionHandle = GLES20.glGetAttribLocation(programHandle, "a_Position");
// Tell OpenGL to use this program when rendering.
GLES20.glUseProgram(programHandle);
}
@Override
public void onSurfaceChanged(GL10 glUnused, int width, int height)
{
// Set the OpenGL viewport to the same size as the surface.
GLES20.glViewport(0, 0, width, height);
// Create a new perspective projection matrix. The height will stay the same
// while the width will vary as per aspect ratio.
final float ratio = (float) width / height;
final float left = -ratio;
final float right = ratio;
final float bottom = -1.0f;
final float top = 1.0f;
final float near = 1.0f;
final float far = 100.0f;
Matrix.frustumM(mProjectionMatrix, 0, left, right, bottom, top, near, far);
}
@Override
public void onDrawFrame(GL10 glUnused)
{
GLES20.glClear(GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);
Matrix.setIdentityM(mModelMatrix, 0);
//Push to the distance - note this will have no effect on a point size
Matrix.translateM(mModelMatrix, 0, 0.0f, 0.0f, -5.0f);
Matrix.multiplyMV(mMVPMatrix, 0, mViewMatrix, 0, mModelMatrix, 0);
Matrix.multiplyMV(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0);
GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mMVPMatrix, 0);
//Send the vertex
GLES20.glVertexAttribPointer(mPositionHandle, 3, GLES20.GL_FLOAT, false, 0, vertexBuf);
GLES20.glEnableVertexAttribArray(mPositionHandle);
//Draw the point
GLES20.glDrawArrays(GLES20.GL_POINTS, 0, 1);
}
}