启动时出现无法理解的错误

Question

对不起，我的英语。我是OpenglES的初学者。我写了这段代码来画出曲棍球的简单表格。该代码摘自Android版《 OpenglES2》，我有点对其进行了修改。当我启动我的应用程序时，它崩溃了。其中没有出现错误。ShaderHandler.java中的代码

public class ShaderHandler {
    private static int program;
    private static final String TAG = "TAG";

    public static int loadShader(int type, String shaderCode){
        final int shader = GLES20.glCreateShader(type);

        if(shader == 0){
            if(LoggerConfig.ON) {
                Log.w(TAG, "Could not create new shader");
            }
        }
        GLES20.glShaderSource(shader, shaderCode);
        GLES20.glCompileShader(shader);

        //----------------------------------------------------------------------------------------
        //check compile status. This is pattern
        final int[] compileStatus = new int[1];
        GLES20.glGetShaderiv(shader, GLES20.GL_COMPILE_STATUS, compileStatus, 0);

        if (LoggerConfig.ON) {
            Log.v(TAG, "Results of compiling source: " + "\n" + shaderCode + "\n:"
                    + GLES20.glGetShaderInfoLog(shader));
        }
        if (compileStatus[0] == 0){
            //if it failed, delete the shader object
            GLES20.glDeleteShader(shader);
            if (LoggerConfig.ON) Log.w(TAG, "Compilation of shader failed");
        }
        //----------------------------------------------------------------------------------------

        return shader;
    }

    public static int makeProgram(int vertexShader, int fragmentShader) {
        program = GLES20.glCreateProgram();
        if (program == 0){
            if (LoggerConfig.ON){
                Log.w(TAG, "Could not create a program");
            }
        }
        GLES20.glAttachShader(program, vertexShader);
        GLES20.glAttachShader(program, fragmentShader);
        GLES20.glLinkProgram(program);

        if(LoggerConfig.ON) validateProgram(program);
        GLES20.glUseProgram(program);

        return program;
    }
}

以及来自myRenderer.java的代码

public class MyRenderer implements GLSurfaceView.Renderer {

    private static final int POSITION_COMPONENT_COUNT = 2;
    private static final int BYTES_PER_FLOAT = 4;
    private FloatBuffer vertexData;
    private Context context;
    private ShaderHandler shaderHandler;
    private static final String A_POSITION = "a_Position";
    private int aPositionLocation;
    private static final String U_COLOR = "u_Color";
    private int uColorLocation;

    private final String vertexShaderCode =
            "attribute vec4 a_Position;" +
                    "void main() {" +
                    "  gl_Position = a_Position;" +
                    "}";

    private final String fragmentShaderCode =
            "precision mediump float;" +
                    "uniform vec4 u_Color;" +
                    "void main() {" +
                    "  gl_FragColor = u_Color;" +
                    "}";

    float[] tableVertices = {
            0f, 0f,
            0f, 14f,
            9f, 14f,
            9f, 0f
    };
    float[] tableVerticesTriangles = {
            //Triangle1
            0f, 0f,
            9f, 14f,
            0f, 14f,

            //Triangle2
            0f, 0f,
            9f, 0f,
            9f, 14f,

            //Line1
            0f, 7f,
            9f, 7f,

            //Mallets
            4.5f, 2f,
            4.5f, 12f
    };
    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
        GLES20.glClearColor(1.0f, 0.0f, 0.0f, 0.0f);

        vertexData = ByteBuffer
                .allocateDirect(tableVerticesTriangles.length * BYTES_PER_FLOAT)
                .order(ByteOrder.nativeOrder())
                .asFloatBuffer();
        vertexData.put(tableVertices);

        int compiledVertShader = shaderHandler.loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode);
        int compiledFragShader = shaderHandler.loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode);

        int program = shaderHandler.makeProgram(compiledVertShader, compiledFragShader);

        aPositionLocation = GLES20.glGetAttribLocation(program, "a_Position");
        uColorLocation = GLES20.glGetUniformLocation(program, "u_Color");

        vertexData.position(0);
        GLES20.glVertexAttribPointer(aPositionLocation, POSITION_COMPONENT_COUNT, GLES20.GL_FLOAT,
                false, 0, vertexData);
        GLES20.glEnableVertexAttribArray(aPositionLocation);

    }

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

    @Override
    public void onDrawFrame(GL10 gl) {
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);

        GLES20.glUniform4f(uColorLocation, 1.0f, 1.0f, 1.0f, 1.0f);
        GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 6);

        GLES20.glUniform4f(uColorLocation, 1.0f, 0.0f, 0.0f, 1.0f);
        GLES20.glDrawArrays(GLES20.GL_LINES, 6, 2);

        GLES20.glUniform4f(uColorLocation, 0.0f, 0.0f, 1.0f, 1.0f);
        GLES20.glDrawArrays(GLES20.GL_POINTS, 8, 1);

        GLES20.glUniform4f(uColorLocation, 1.0f, 0.0f, 0.0f, 1.0f);
        GLES20.glDrawArrays(GLES20.GL_POINTS, 9, 1);
    }
}

在应用崩溃后，我在logcat中看到此消息

A/libc: Fatal signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x0 in tid 17311 (GLThread 891), pid 17264 (ockey.airhockey)

请帮助。我整天都在努力解决这个问题，但我不知道该怎么办。

Answer 1

创建缓冲区并填充缓冲区后，您错过了vertexData.flip()。

vertexData.put(tableVertices);

vertexData.put(tableVertices).flip();

vertexData.put(tableVertices)将数据从当前位置（在此情况下为缓冲区的开始）开始传输到缓冲区。缓冲区位置增加数据大小。因此，新的缓冲区位置在新数据的末尾。

[flip()将缓冲区的限制（长度）设置为当前位置，然后将该位置设置为零。