glMapBufferRange在Android GLES应用程序上崩溃

Question

I am trying to morph some vertices on a GLES application on android and glMapBufferRange keeps crashing with the following error:

SIGSEGV (signal SIGSEGV: address access protected (fault address: 0xef13d664))

I more or less followed the example of this web-site:

http://www.songho.ca/opengl/gl_vbo.html#update

but not sure if I am missing something.

I created my VBOs at initialization time and I can draw the object with no issues. The code of creation goes:

void SubObject3D::CreateVBO(VBOInfo &vboInfoIn) {
    // m_vboIds[0] - used to store vertex attribute data
    // m_vboIds[l] - used to store element indices
    glGenBuffers(2, vboInfoIn.vboIds);

    // Let the buffer all dynamic for morphing
    glBindBuffer(GL_ARRAY_BUFFER, vboInfoIn.vboIds[0]);
    glBufferData(GL_ARRAY_BUFFER,
                 (GLsizeiptr) (vboInfoIn.vertexStride * vboInfoIn.verticesCount),
                 vboInfoIn.pVertices, GL_DYNAMIC_DRAW);

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vboInfoIn.vboIds[1]);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER,
                 (GLsizeiptr) (sizeof(GLushort) * vboInfoIn.indicesCount),
                 vboInfoIn.pIndices, GL_STATIC_DRAW);
}

struct VBOInfo {
    VBOInfo() {
        memset(this, 0x00, sizeof(VBOInfo));
        vboIds[0] = 0xdeadbeef;
        vboIds[1] = 0xdeadbeef;
    }

    // VertexBufferObject Ids
    GLuint vboIds[2];

    // Points to the source data
    GLfloat *pVertices;         // Pointer of original data
    GLuint verticesCount;
    GLushort *pIndices;         // Pointer of original data
    GLuint indicesCount;

    GLint vertexStride;
};

then later in the Rendering loop I tried to get the hold of my vertex pointer as such:

// I stored the information at creation time here:
VBOInfo mVBOGeometryInfo;
//later I call here to get the pointer
GLfloat *SubObject3D::MapVBO() {
    GLfloat *pVertices = nullptr;

    glBindBuffer(GL_ARRAY_BUFFER, mVBOGeometryInfo.vboIds[0]);

    GLsizeiptr length = (GLsizeiptr) (mVBOGeometryInfo.vertexStride *
                                      mVBOGeometryInfo.verticesCount);
    pVertices = (GLfloat *) glMapBufferRange(
            GL_ARRAY_BUFFER, 0,
            length,
            GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT
    );

    if (pVertices == nullptr) {
        LOGE ("Could not map VBO");
    }
    return pVertices;
}

but it crashed right at glMapBufferRange.

This is an android application that uses NDK. The hardware is a Samsung S6 phone.

thx!

Answer 1

This was quite painful to resolve this issue, but there is no problem with the code above per se. It was basically the include. My code was based off the google sample "more teapots" located here:

https://github.com/googlesamples/android-ndk/tree/master/teapots

I had to follow their pattern and change my include to GLES from:

#include <GLES3/gl3.h>

to use their stubs:

#include "gl3stub.h"

why? I don't know, but likely causing the linker to link incorrect code.