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docs.GL

glCreateShader

Name

glCreateShader — create a shader object

C Specification

GLuint glCreateShader(GLenum shaderType);

Parameters

shaderType

Specifies the type of shader to be created. Must be either GL_VERTEX_SHADER or GL_FRAGMENT_SHADER.

Description

glCreateShader creates an empty shader object and returns a non-zero value by which it can be referenced. A shader object is used to maintain the source code strings that define a shader. shaderType indicates the type of shader to be created. Two types of shaders are supported. A shader of type GL_VERTEX_SHADER is a shader that is intended to run on the programmable vertex processor. A shader of type GL_FRAGMENT_SHADER is a shader that is intended to run on the programmable fragment processor.

When created, a shader object's GL_SHADER_TYPE parameter is set to either GL_VERTEX_SHADER or GL_FRAGMENT_SHADER, depending on the value of shaderType.

Notes

Like texture objects, the name space for shader objects may be shared across a set of contexts, as long as the server sides of the contexts share the same address space. If the name space is shared across contexts, any attached objects and the data associated with those attached objects are shared as well.

Applications are responsible for providing the synchronization across API calls when objects are accessed from different execution threads.

Errors

This function returns 0 if an error occurs creating the shader object.

GL_INVALID_ENUM is generated if shaderType is not an accepted value.

Associated Gets

glGetShaderiv with a valid shader object and the parameter to be queried

glGetShaderInfoLog with a valid shader object

glGetShaderSource with a valid shader object

glIsShader

Examples

Compile a program from a vertex shader and a fragment shader.
GLuint vshader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vshader, 1, &vertex_shader_source, NULL); // vertex_shader_source is a GLchar* containing glsl shader source code
glCompileShader(vshader);

GLint vertex_compiled;
glGetShaderiv(vshader, GL_COMPILE_STATUS, &vertex_compiled);
if (vertex_compiled != GL_TRUE)
{
    GLsizei log_length = 0;
    GLchar message[1024];
    glGetShaderInfoLog(vshader, 1024, &log_length, message);
    // Write the error to a log
}

GLuint fshader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fshader, 1, &fragment_shader_source, NULL); // fragment_shader_source is a GLchar* containing glsl shader source code
glCompileShader(fshader);

GLint fragment_compiled;
glGetShaderiv(fshader, GL_COMPILE_STATUS, &fragment_compiled);
if (fragment_compiled != GL_TRUE)
{
    GLsizei log_length = 0;
    GLchar message[1024];
    glGetShaderInfoLog(fshader, 1024, &log_length, message);
    // Write the error to a log
}

GLuint program = glCreateProgram();

// This step is unnecessary if you use the location specifier in your shader
// e.g. layout (location = 0) in vec3 position;
glBindAttribLocation(program, 0, "position"); // The index passed into glBindAttribLocation is
glBindAttribLocation(program, 1, "texcoord"); // used by glEnableVertexAttribArray. "position"
glBindAttribLocation(program, 2, "normal");   // "texcoord" "normal" and "color" are the names of the
glBindAttribLocation(program, 3, "color");    // respective inputs in your fragment shader.

glAttachShader(program, vshader);
glAttachShader(program, fshader);
glLinkProgram(program);

GLint program_linked;
glGetProgramiv(program, GL_LINK_STATUS, &program_linked);
if (program_linked != GL_TRUE)
{
    GLsizei log_length = 0;
    GLchar message[1024];
    glGetProgramInfoLog(program, 1024, &log_length, message);
    // Write the error to a log
}

See Also

glAttachShader, glCompileShader, glDeleteShader, glDetachShader, glShaderSource, glShaderBinary

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