OpenGLESv2 Shader glGetAttribLocation returns -1

Hey, I try to code a OpenGL ES 2 engine but at shader creation the function glGetAttribLocation returns开发者_如何学运维 -1 which means

The named attribute variable is not an active attribute in the specified program object or the name starts with the reserved prefix "gl_".

But it IS defined in the shader and doesnt start with gl_. Whats wrong with my code?

C++ Code:

glprogram = glCreateProgram();

glvertshader = glCreateShader(GL_VERTEX_SHADER);
glfragshader = glCreateShader(GL_FRAGMENT_SHADER);

glShaderSource(glvertshader, 1, vertsrc, NULL);
glShaderSource(glfragshader, 1, fragsrc, NULL);

GLint ret;

glCompileShader(glvertshader);
glGetShaderiv(glvertshader, GL_COMPILE_STATUS, &ret);
if(!ret)
{
    ///error handling - stripped for the internet
}

glCompileShader(glfragshader);
glGetShaderiv(glfragshader, GL_COMPILE_STATUS, &ret);
if(!ret)
{
    ///error handling - stripped for the internet
}

glAttachShader(glprogram, glvertshader);
glAttachShader(glprogram, glfragshader);

glLinkProgram(glprogram);

glGetProgramiv(glprogram, GL_LINK_STATUS, &ret);
if(!ret)
{
    ///error handling - stripped for the internet
}

glattributes[0] = glGetAttribLocation(glprogram, "vertex");
glattributes[1] = glGetAttribLocation(glprogram, "texcoord_vs");



std::cout << "texcoord " << glGetAttribLocation(glprogram, "texcoord_vs";

Vert shader:

// Vertex Shader for OpenGL ES
uniform mat4 projmat;
uniform mat4 modviewmat;

attribute vec2 vertex;
attribute vec2 texcoord_vs;

varying vec2 texcoord_fs;

void main()
{
    texcoord_fs = texcoord_vs;
    gl_Position = projmat*modviewmat*vec4(vertex, 0.0, 1.0);
}

edit: correct shader code and the error is with texcoord_vs.

You didn't specify which attribute is not used, but I assume it's "texcoord_vs", simply because you're not using it, and as such it's being stripped by the shader compiler.

I suppose you meant to say texcoord_fs = texcoord_vs?