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docs.GL

glBlitFramebuffer

Name

glBlitFramebuffer, glBlitNamedFramebuffer — copy a block of pixels from one framebuffer object to another

C Specification

void glBlitFramebuffer( GLint srcX0,
GLint srcY0,
GLint srcX1,
GLint srcY1,
GLint dstX0,
GLint dstY0,
GLint dstX1,
GLint dstY1,
GLbitfield mask,
GLenum filter);
void glBlitNamedFramebuffer( GLuint readFramebuffer,
GLuint drawFramebuffer,
GLint srcX0,
GLint srcY0,
GLint srcX1,
GLint srcY1,
GLint dstX0,
GLint dstY0,
GLint dstX1,
GLint dstY1,
GLbitfield mask,
GLenum filter);

Parameters

readFramebuffer

Specifies the name of the source framebuffer object for glBlitNamedFramebuffer.

drawFramebuffer

Specifies the name of the destination framebuffer object for glBlitNamedFramebuffer.

srcX0, srcY0, srcX1, srcY1

Specify the bounds of the source rectangle within the read buffer of the read framebuffer.

dstX0, dstY0, dstX1, dstY1

Specify the bounds of the destination rectangle within the write buffer of the write framebuffer.

mask

The bitwise OR of the flags indicating which buffers are to be copied. The allowed flags are GL_COLOR_BUFFER_BIT, GL_DEPTH_BUFFER_BIT and GL_STENCIL_BUFFER_BIT.

filter

Specifies the interpolation to be applied if the image is stretched. Must be GL_NEAREST or GL_LINEAR.

Description

glBlitFramebuffer and glBlitNamedFramebuffer transfer a rectangle of pixel values from one region of a read framebuffer to another region of a draw framebuffer.

For glBlitFramebuffer, the read and draw framebuffers are those bound to the GL_READ_FRAMEBUFFER and GL_DRAW_FRAMEBUFFER targets respectively.

For glBlitNamedFramebuffer, readFramebuffer and drawFramebuffer are the names of the read read and draw framebuffer objects respectively. If readFramebuffer or drawFramebuffer is zero, then the default read or draw framebuffer respectively is used.

mask is the bitwise OR of a number of values indicating which buffers are to be copied. The values are GL_COLOR_BUFFER_BIT, GL_DEPTH_BUFFER_BIT, and GL_STENCIL_BUFFER_BIT. The pixels corresponding to these buffers are copied from the source rectangle bounded by the locations (srcX0, srcY0) and (srcX1, srcY1) to the destination rectangle bounded by the locations (dstX0, dstY0) and (dstX1, dstY1). The lower bounds of the rectangle are inclusive, while the upper bounds are exclusive.

The actual region taken from the read framebuffer is limited to the intersection of the source buffers being transferred, which may include the color buffer selected by the read buffer, the depth buffer, and/or the stencil buffer depending on mask. The actual region written to the draw framebuffer is limited to the intersection of the destination buffers being written, which may include multiple draw buffers, the depth buffer, and/or the stencil buffer depending on mask. Whether or not the source or destination regions are altered due to these limits, the scaling and offset applied to pixels being transferred is performed as though no such limits were present.

If the sizes of the source and destination rectangles are not equal, filter specifies the interpolation method that will be applied to resize the source image , and must be GL_NEAREST or GL_LINEAR. GL_LINEAR is only a valid interpolation method for the color buffer. If filter is not GL_NEAREST and mask includes GL_DEPTH_BUFFER_BIT or GL_STENCIL_BUFFER_BIT, no data is transferred and a GL_INVALID_OPERATION error is generated.

If filter is GL_LINEAR and the source rectangle would require sampling outside the bounds of the source framebuffer, values are read as if the GL_CLAMP_TO_EDGE texture wrapping mode were applied.

When the color buffer is transferred, values are taken from the read buffer of the specified read framebuffer and written to each of the draw buffers of the specified draw framebuffer.

If the source and destination rectangles overlap or are the same, and the read and draw buffers are the same, the result of the operation is undefined.

Errors

GL_INVALID_OPERATION is generated by BlitNamedFramebuffer if readFramebuffer or drawFramebuffer is not zero or the name of an existing framebuffer object.

GL_INVALID_OPERATION is generated if mask contains any of the GL_DEPTH_BUFFER_BIT or GL_STENCIL_BUFFER_BIT and filter is not GL_NEAREST.

GL_INVALID_OPERATION is generated if mask contains GL_COLOR_BUFFER_BIT and any of the following conditions hold:

  • The read buffer contains fixed-point or floating-point values and any draw buffer contains neither fixed-point nor floating-point values.

  • The read buffer contains unsigned integer values and any draw buffer does not contain unsigned integer values.

  • The read buffer contains signed integer values and any draw buffer does not contain signed integer values.

GL_INVALID_OPERATION is generated if mask contains GL_DEPTH_BUFFER_BIT or GL_STENCIL_BUFFER_BIT and the source and destination depth and stencil formats do not match.

GL_INVALID_OPERATION is generated if filter is GL_LINEAR and the read buffer contains integer data.

GL_INVALID_OPERATION is generated if the effective value of GL_SAMPLES for the read and draw framebuffers is not identical.

GL_INVALID_OPERATION is generated if the value of GL_SAMPLE_BUFFERS for both read and draw buffers is greater than zero and the dimensions of the source and destination rectangles is not identical.

GL_INVALID_FRAMEBUFFER_OPERATION is generated if the specified read and draw framebuffers are not framebuffer complete.

Examples

Copy the contents of one framebuffer object to another by blitting.
glBindFramebuffer(GL_READ_FRAMEBUFFER, source_fbo);
glBindFramebuffer(GL_DRAW_FRAMEBUFFER, destination_fbo);

glBlitFramebuffer(0, 0, source_fbo_width, source_fbo_height, 0, 0, destination_fbo_width, destination_fbo_height, GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT, GL_NEAREST);

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
glBlitFramebuffer - - ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔
glBlitNamedFramebuffer - - - - - - - - - - - ✔
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