Question

我正在尝试在Android上构建一个小的Open GL2.0演示应用程序，但我收到以下错误

日志cat中的

07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context     (logged once per thread)
07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context         (logged once per thread)
07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context     (logged once per thread)
07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread)
07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread)
07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread)
07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread)
07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread)
07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread)
07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread)

控制台中的

[2012-07-02 20:50:44 - Emulator]     development/tools/emulator/opengl/host/libs/Translator/GLES_V2/GLESv2Imp.cpp:glGetAttribLoc    ation:826 error 0x501
[2012-07-02 20:50:44 - Emulator]     development/tools/emulator/opengl/host/libs/Translator/GLES_V2/GLESv2Imp.cpp:glGetUniformLocation:1383 error 0x501

我的代码

查看

package limitliss.graphics.play;


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.content.Context;
import android.opengl.GLES20;
import android.opengl.GLSurfaceView;
import android.opengl.GLSurfaceView.Renderer;
import android.opengl.GLU;

public class OGLView extends GLSurfaceView implements Renderer {

private int mColorType = 0;

private float rotx = 0.0f;
private float roty = 0.0f;    
Triangle tri = new Triangle();

public OGLView(Context context) {
    super(context);
    setEGLContextClientVersion(2);

    this.setRenderer(this); 
    setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
    // TODO Auto-generated constructor stub
}



public static int loadShader(int type, String shaderCode){

    // create a vertex shader type (GLES20.GL_VERTEX_SHADER)
    // or a fragment shader type (GLES20.GL_FRAGMENT_SHADER)
    int shader = GLES20.glCreateShader(type);

    // add the source code to the shader and compile it
    GLES20.glShaderSource(shader, shaderCode);
    GLES20.glCompileShader(shader);

    return shader;
}





public void onSurfaceCreated(GL10 unused, EGLConfig config) {
    // Set the background frame color
    GLES20.glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
    tri.draw();
}

public void onDrawFrame(GL10 unused) {
    // Redraw background color
    GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
    tri.draw();
}

public void onSurfaceChanged(GL10 unused, int width, int height) {
    GLES20.glViewport(0, 0, width, height);
}
}


Triangle

package limitliss.graphics.play;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;

import javax.microedition.khronos.opengles.GL10;

import android.opengl.GLES20;



public class Triangle {

float color[] = { 0.63671875f, 0.76953125f, 0.22265625f, 1.0f };

private FloatBuffer vertexBuffer;
int mProgram;
int mPositionHandle;
private final String vertexShaderCode =
        "attribute vec4 vPosition;" +
        "void main() {" +
        "  gl_Position = vPosition;" +
        "}";

    private final String fragmentShaderCode =
        "precision mediump float;" +
        "uniform vec4 vColor;" +
        "void main() {" +
        "  gl_FragColor = vColor;" +
        "}";
// number of coordinates per vertex in this array
static final int COORDS_PER_VERTEX = 3;
static float triangleCoords[] = { // in counterclockwise order:
     0.0f,  0.622008459f, 0.0f,   // top
    -0.5f, -0.311004243f, 0.0f,   // bottom left
     0.5f, -0.311004243f, 0.0f};   // bottom right

public Triangle() {
    // initialize vertex byte buffer for shape coordinates
    ByteBuffer bb = ByteBuffer.allocateDirect(
            // (number of coordinate values * 4 bytes per float)
            triangleCoords.length * 4);
    // use the device hardware's native byte order
    bb.order(ByteOrder.nativeOrder());

    // create a floating point buffer from the ByteBuffer
    vertexBuffer = bb.asFloatBuffer();
    // add the coordinates to the FloatBuffer
    vertexBuffer.put(triangleCoords);
    // set the buffer to read the first coordinate
    vertexBuffer.position(0);

    int vertexShader =  OGLView.loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode);
    int fragmentShader =  OGLView.loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode);

    mProgram = GLES20.glCreateProgram();             // create empty OpenGL ES Program
    GLES20.glAttachShader(mProgram, vertexShader);   // add the vertex shader to program
    GLES20.glAttachShader(mProgram, fragmentShader); // add the fragment shader to program
    GLES20.glLinkProgram(mProgram);    
}

public void draw() {

    // Add program to OpenGL ES environment
    GLES20.glUseProgram(mProgram);

    // get handle to vertex shader's vPosition member
    mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");

    // Enable a handle to the triangle vertices
    GLES20.glEnableVertexAttribArray(mPositionHandle);

    // Prepare the triangle coordinate data
    GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX,
                                 GLES20.GL_FLOAT, false,
                                 COORDS_PER_VERTEX, vertexBuffer);

    // get handle to fragment shader's vColor member
    int mColorHandle = GLES20.glGetUniformLocation(mProgram, "vColor");

    // Set color for drawing the triangle
    GLES20.glUniform4fv(mColorHandle, 1, color, 0);

    // Draw the triangle
    GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 3);

    // Disable vertex array
    GLES20.glDisableVertexAttribArray(mPositionHandle);
}

public void render(GL10 gl){

    gl.glPushMatrix();
    gl.glColor4f(this.color[0],this.color[1],this.color[2],this.color[3]); 
    gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer);
    gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
    gl.glDrawArrays(GL10.GL_TRIANGLE_FAN, 0, 3);
    gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
    gl.glPopMatrix();
}
}

Answer 1

您收到call to OpenGL ES API with no current context错误，因为您在OpenGL线程之外创建了三角形Triangle tri = new Triangle();（并且三角形构造函数正在进行opengl调用）。只有OpenGL回调中的代码（onSurfaceCreated，onDrawFrame等）才会在opengl线程上执行。

将tri = new Triangle()放在onSurfaceCreated内，这些错误应该消失。

Answer 2

添加私人最终上下文上下文; 就在下面的“公共类OGLView扩展GLSurfaceView实现Renderer {”

打开GL 2.0 Android错误0x501（GL_INVALID_VALUE）

2 个答案: