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glEnableVertexAttribArray

Name

glEnableVertexAttribArray — Enable or disable a generic vertex attribute array

C Specification

void glEnableVertexAttribArray( GLuint index);
void glDisableVertexAttribArray( GLuint index);
void glEnableVertexArrayAttrib( GLuint vaobj,
GLuint index);
void glDisableVertexArrayAttrib( GLuint vaobj,
GLuint index);

Parameters

vaobj

Specifies the name of the vertex array object for glDisableVertexArrayAttrib and glEnableVertexArrayAttrib functions.

index

Specifies the index of the generic vertex attribute to be enabled or disabled.

Description

glEnableVertexAttribArray and glEnableVertexArrayAttrib enable the generic vertex attribute array specified by index. glEnableVertexAttribArray uses currently bound vertex array object for the operation, whereas glEnableVertexArrayAttrib updates state of the vertex array object with ID vaobj.

glDisableVertexAttribArray and glDisableVertexArrayAttrib disable the generic vertex attribute array specified by index. glDisableVertexAttribArray uses currently bound vertex array object for the operation, whereas glDisableVertexArrayAttrib updates state of the vertex array object with ID vaobj.

By default, all client-side capabilities are disabled, including all generic vertex attribute arrays. If enabled, the values in the generic vertex attribute array will be accessed and used for rendering when calls are made to vertex array commands such as glDrawArrays, glDrawElements, glDrawRangeElements, glMultiDrawElements, or glMultiDrawArrays.

Errors

GL_INVALID_OPERATION is generated by glEnableVertexAttribArray and glDisableVertexAttribArray if no vertex array object is bound.

GL_INVALID_OPERATION is generated by glEnableVertexArrayAttrib and glDisableVertexArrayAttrib if vaobj is not the name of an existing vertex array object.

GL_INVALID_VALUE is generated if index is greater than or equal to GL_MAX_VERTEX_ATTRIBS.

Associated Gets

glGet with argument GL_MAX_VERTEX_ATTRIBS

glGetVertexAttrib with arguments index and GL_VERTEX_ATTRIB_ARRAY_ENABLED

glGetVertexAttribPointerv with arguments index and GL_VERTEX_ATTRIB_ARRAY_POINTER

Examples

Render an indexed buffer object using texture UV and normal vertex attributes.
glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer); // vertex_buffer is retrieved from glGenBuffers
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_buffer); // index_buffer is retrieved from glGenBuffers

glEnableVertexAttribArray(texcoord_attrib_index); // Attribute indexes were received from calls to glGetAttribLocation, or passed into glBindAttribLocation.
glEnableVertexAttribArray(normal_attrib_index);
glEnableVertexAttribArray(position_attrib_index);

// vertex_stride is the size of bytes of each vertex in the buffer object
// vertex_position_offset and kin are the offset in bytes of the position data
// in each vertex. For example if your vertex structure is
// [ position, texcoord, normal ] then position vertex_position_offset will
// have offset 0, vertex_texcoord_offset is 12 (position is 3 * sizeof(float)
// bytes large, and texcoord comes just after) and vertex_normal_offset is
// 20 = 5 * sizeof(float).
GLintptr vertex_texcoord_offset = 3 * sizeof(float);
GLintptr vertex_normal_offset = 5 * sizeof(float);
GLintptr vertex_position_offset = 0 * sizeof(float);

glVertexAttribPointer(texcoord_attrib_index, 2, GL_FLOAT, false, vertex_stride, (GLvoid*)vertex_texcoord_offset);
glVertexAttribPointer(normal_attrib_index, 3, GL_FLOAT, false, vertex_stride, (GLvoid*)vertex_normal_offset);
glVertexAttribPointer(position_attrib_index, 3, GL_FLOAT, false, vertex_stride, (GLvoid*)vertex_position_offset);

// num_vertices is the number of verts in your vertex_data.
// index_data is an array of unsigned int offsets into vertex_data.
glDrawElements(GL_TRIANGLES, num_vertices, GL_UNSIGNED_INT, NULL);

glDisableVertexAttribArray(position_attrib_index);
glDisableVertexAttribArray(texcoord_attrib_index);
glDisableVertexAttribArray(normal_attrib_index);

Version Support

OpenGL Version
Function / Feature Name 2.0 2.1 3.0 3.1 3.2 3.3 4.0 4.1 4.2 4.3 4.4 4.5
glDisableVertexArrayAttrib - - - - - - - - - - - ✔
glDisableVertexAttribArray ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔
glEnableVertexArrayAttrib - - - - - - - - - - - ✔
glEnableVertexAttribArray ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔
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