glUniformMatrix4fv失败,错误代码为GL_INVALID_OPERATION

Question

我试图绑定一个统一的4x4矩阵运气不好.我用这个程序瞄准OpenGL 3.3,但我的环境是OpenGL 4.2.我有一个函数,它简单地将一个单位矩阵绑定到我的顶点着色器中的一个统一体,但是对glUniformMatrix4fv的调用因GL_INVALID_OPERATION而失败.

这是我的顶点着色器:

#version 330
in vec4 in_vertex;
uniform mat4 mvMatrix;
void main(void) {
    gl_Position = mvMatrix * in_vertex;
}

我知道矩阵换位和左/右乘法的缺陷,但我认为这是一场战斗,因为我可以实际传递均匀矩阵.

这是一个简单的函数,在我遇到问题的函数中引用.我现在只使用它来尝试确定发生错误的地方.由于glUniformMatrix4fv的评估全部在服务器端,我没有办法使用断点等.

inline void die_on_gl_error(const char* location) {
    GLenum error = GL_NO_ERROR;
    error = glGetError();
    if (GL_NO_ERROR != error) {
        printf("GL Error %x encountered in %s.\n", error, location);
        exit(1);
    }
}

该SDK文档说,有几个原因glMatrixUniform4fv可以设置GL_INVALID_OPERATION:

1. 如果没有当前程序对象,则生成GL_INVALID_OPERATION.
2. 如果着色器中声明的统一变量的大小与glUniform命令指示的大小不匹配,则生成GL_INVALID_OPERATION.
3. 如果此函数的一个整数变量用于加载float,vec2,vec3,vec4或其数组的统一变量,或者如果使用此函数的某个浮点变体,则生成GL_INVALID_OPERATION加载int,ivec2,ivec3或ivec4类型的统一变量,或者这些变量的数组.
4. 如果location是当前程序对象的无效统一位置且位置不等于-1,则生成GL_INVALID_OPERATION.
5. 如果count大于1且指示的统一变量不是数组变量,则生成GL_INVALID_OPERATION.
6. 如果使用glUniform1i和glUniform1iv以外的命令加载采样器,则会生成GL_INVALID_OPERATION.
7. 如果在执行glBegin和glEnd的相应执行之间执行glUniform,则生成GL_INVALID_OPERATION.

对于上下文,调用此函数的对象具有一个名为active_program的参数,用于存储当前激活的GLSL程序的编号.identity_matrix声明为:

float identity_matrix[16];

并定义为:

identity_matrix = {
            1.0f, 0.0f, 0.0f, 0.0f,
            0.0f, 1.0f, 0.0f, 0.0f,
            0.0f, 0.0f, 1.0f, 0.0f,
            0.0f, 0.0f, 0.0f, 1.0f
};

不用多说,这就是给我带来麻烦的:

void VSGL::load_identity_matrix() {
// GL_INVALID_OPERATION is generated if there is no current program object.
if (!glIsProgram(active_program)) {
    printf("Active program is not valid.\n");
    exit(1);
}

// ... active_program is a program, but is it valid?
GLint program_valid = 0;
glValidateProgram(active_program);
glGetProgramiv(active_program, GL_VALIDATE_STATUS, &program_valid);
if (GL_TRUE != program_valid) {
    printf("Program validation failed.\n");
    exit(1);
}
die_on_gl_error("GetProgram (Validate Status)");

// ... makes sure there is a program active, and the current program matches
// the value stored in active_program.
GLint current_program = 0;
glGetIntegerv(GL_CURRENT_PROGRAM, &current_program);
if (0 == current_program) {
    printf("Error, no current program is set.\n");
    exit(1);
} else if (current_program != active_program) {
    printf("Error, current program doesn't match active_program!\n");
}
die_on_gl_error("GetInteger");

// ... ensures the program actually has an active uniform, as the docs
// say that uniforms can be optimized out if they don't contribute to
// out results.
GLint num_active_uniforms = 0;
glGetProgramiv(active_program, GL_ACTIVE_UNIFORMS, &num_active_uniforms);
if (0 == num_active_uniforms) {
    printf("There are 0 uniforms active in program %d.\n", active_program);
    exit(1);
} else {
    printf("There are %d uniform(s) active in program %d.\n", num_active_uniforms, active_program);
}
die_on_gl_error("GetProgram (Active Uniforms)");

// GL_INVALID_OPERATION is generated if the size of the uniform variable
// declared in the shader does not match the size indicated by the glUniform
// command.

// GL_INVALID_OPERATION is generated if location is an invalid uniform location
// for the current program object and location is not equal to -1.

// ... gets some basic information about the active uniforms, of which there
// should be only one, a FLOAT_MAT4 of size 1.
const GLchar *uniform_name = "mvMatrix";
GLint location = glGetUniformLocation(active_program, uniform_name);
die_on_gl_error("GetUniformLocation");

GLchar *message;
GLint max_uniform_length;
glGetProgramiv(active_program, GL_ACTIVE_UNIFORM_MAX_LENGTH, &max_uniform_length);
message = new GLchar[max_uniform_length];
GLint size;
GLenum type;
glGetActiveUniform(active_program, location, max_uniform_length, NULL, &size, &type, message);
printf("Uniform %s:\tType:%x\tSize:%d\n", message, type, size);
if (GL_FLOAT_MAT4 != type) {
    printf("Active uniform at location is not a 4x4 float matrix.\n");
}
die_on_gl_error("GetActiveUniform");

// GL_INVALID_OPERATION is generated if count is greater than 1 and the indicated
// uniform variable is not an array variable.

// GL_INVALID_OPERATION is generated if a sampler is loaded using a command other than
// glUniform1i and glUniform1iv.

// GL_INVALID_OPERATION is generated if glUniform is executed between the execution
// of glBegin and the corresponding execution of glEnd.

// None of the above are true, and yet the following dies with GL_INVALID_OPERATION?
glUniformMatrix4fv(location, 1, false, identity_matrix);
die_on_gl_error("UniformMatrix4f");
}

毕竟,这是输出:

There are 1 uniform(s) active in program 3.
Uniform mvMatrix:   Type:8b5c   Size:1
GL Error 502 encountered in UniformMatrix4f.

类型8b5c当然是GL_FLOAT_MAT4,当然大小是1,所以我看不出哪个无效的操作条件正在咬我!

编辑:

这是main中的循环,其中调用了UseProgram和this函数:

    while (wm->update()) {
        wm->poll_input();
        handle_input(viewingmatrix);
        if (!gl->use_program(program))
            exit(-1);
        gl->load_identity_matrix();
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glDrawArrays(GL_TRIANGLES, 0, bananaNumVerts);
        glFlush();
        usleep(16667);
    }

gl->use_program(program) 只是一个包装器,它检查传入的int的有效性并更新对象的active_program参数.

编辑2:感谢 luke指向我的gDEBugger,它也检测到GL错误.在gDEBugger的调用信息中,我注意到只列出了三个参数.虽然我认为这可能是因为第四个是指向数组的指针(它是驻留在客户端,还是每次调用glUniform时都传递给服务器端？),它让我想到了其他可能是什么原因.

如果它是证明,glUniformMatrix4fv当然实际上是一个函数指针,它获取它的地址,如下所示:

宣言:

PFNGLUNIFORMMATRIX4FV glUniformMatrix4fv;

分配:

glUniformMatrix4fv = (PFNGLUNIFORMMATRIX4FVPROC)glXGetProcAddress((const GLubyte*)"glUniform4fv");

这是我出于学术原因避免使用GLEW的原因.然而,当我翻阅glext.h,我注意到,有也是一个PFNGLUNIFORMMATRIX4FVARBPROC,这我相信只是有书面的代码库之前,此功能是通过与核心.如果不是这样,请告诉我.

Answer 1

看看你的glXGetProcAddress电话:

glUniformMatrix4fv = (PFNGLUNIFORMMATRIX4FVPROC)glXGetProcAddress((const GLubyte*)"glUniform4fv");

你请求glUniform4fv而不是glUniformMatrix4fv!

我知道你说你出于学术原因没有使用扩展包装库,但我仍然强烈推荐它们.