Specifies the window x coordinate of the first pixel that is read from the frame buffer. This location is the lower left corner of a rectangular block of pixels.
Specifies the window y coordinate of the first pixel that is read from the frame buffer. This location is the lower left corner of a rectangular block of pixels.
Specifies the width of the pixel rectangle. width of one correspond to a single pixel.
Specifies the height of the pixel rectangle. height of one corresponds to a single pixel.
Specifies the format of the pixel data. The following symbolic values are accepted: GL_STENCIL_INDEX, GL_DEPTH_COMPONENT, GL_DEPTH_STENCIL, GL_RED, GL_GREEN, GL_BLUE, GL_RGB, GL_BGR, GL_RGBA, and GL_BGRA.
Specifies the data type of the pixel data. Must be one of GL_UNSIGNED_BYTE, GL_BYTE, GL_UNSIGNED_SHORT, GL_SHORT, GL_UNSIGNED_INT, GL_INT, GL_HALF_FLOAT, GL_FLOAT, GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV, GL_UNSIGNED_SHORT_5_6_5, GL_UNSIGNED_SHORT_5_6_5_REV, GL_UNSIGNED_SHORT_4_4_4_4, GL_UNSIGNED_SHORT_4_4_4_4_REV, GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV, GL_UNSIGNED_INT_8_8_8_8, GL_UNSIGNED_INT_8_8_8_8_REV, GL_UNSIGNED_INT_10_10_10_2, GL_UNSIGNED_INT_2_10_10_10_REV, GL_UNSIGNED_INT_24_8, GL_UNSIGNED_INT_10F_11F_11F_REV, GL_UNSIGNED_INT_5_9_9_9_REV, or GL_FLOAT_32_UNSIGNED_INT_24_8_REV.
Returns the pixel data.
Generated using TypeDoc
glReadPixelsreturns pixel data from the frame buffer, starting with the pixel whose lower left corner is at location (x, y), into client memory starting at location data. Several parameters control the processing of the pixel data before it is placed into client memory. These parameters are set with glPixelStore. This reference page describes the effects onglReadPixelsof most, but not all of the parameters specified by these three commands.If a non-zero named buffer object is bound to the GL_PIXEL_PACK_BUFFER target (see glBindBuffer) while a block of pixels is requested, data is treated as a byte offset into the buffer object's data store rather than a pointer to client memory.
glReadPixelsreturns values from each pixel with lower left corner at (𝐱 + 𝐢, 𝐲 + 𝐣) for 0 <= 𝐢 < width and 0 <= 𝐣 < height. This pixel is said to be the 𝐢ᵗʰ pixel in the 𝐣ᵗʰ row. Pixels are returned in row order from the lowest to the highest row, left to right in each row.format specifies the format for the returned pixel values; accepted values are:
GL_STENCIL_INDEX Stencil values are read from the stencil buffer. Each index is converted to fixed point.
GL_DEPTH_COMPONENT Depth values are read from the depth buffer. Each component is converted to floating point such that the minimum depth value maps to 0 and the maximum value maps to 1. Each component is clamped to the range [0,1].
GL_DEPTH_STENCIL Values are taken from both the depth and stencil buffers. The type parameter must be GL_UNSIGNED_INT_24_8 or GL_FLOAT_32_UNSIGNED_INT_24_8_REV.
GL_RED
GL_GREEN
GL_BLUE
GL_RGB
GL_BGR
GL_RGBA
GL_BGRA
Finally, the indices or components are converted to the proper format, as specified by type. If format is GL_STENCIL_INDEX and type is not GL_FLOAT, each index is masked with the mask value given in the following table. If type is GL_FLOAT, then each integer index is converted to single-precision floating-point format.
If format is GL_RED, GL_GREEN, GL_BLUE, GL_RGB, GL_BGR, GL_RGBA, or GL_BGRA and type is not GL_FLOAT, each component is multiplied by the multiplier shown in the following table. If type is GL_FLOAT, then each component is passed as is (or converted to the client's single-precision floating-point format if it is different from the one used by the GL).
Return values are placed in memory as follows. If format is GL_STENCIL_INDEX, GL_DEPTH_COMPONENT, GL_RED, GL_GREEN, or GL_BLUE, a single value is returned and the data for the 𝐢ᵗʰ pixel in the 𝐣ᵗʰ row is placed in location (𝐣)width + 𝐢. GL_RGB and GL_BGR return three values, GL_RGBA and GL_BGRA return four values for each pixel, with all values corresponding to a single pixel occupying contiguous space in data. Storage parameters set by glPixelStore, such as GL_PACK_LSB_FIRST and GL_PACK_SWAP_BYTES, affect the way that data is written into memory. See glPixelStore for a description.