glLogicOp

NAME

glLogicOp -- specify a logical pixel operation for rendering

C SPECIFICATION

void glLogicOp(GLenum opcode)

PARAMETERS

opcode: Specifies a symbolic constant that selects a logical operation. The following symbols are accepted: GL_CLEAR, GL_SET, GL_COPY, GL_COPY_INVERTED, GL_NOOP, GL_INVERT, GL_AND, GL_NAND, GL_OR, GL_NOR, GL_XOR, GL_EQUIV, GL_AND_REVERSE, GL_AND_INVERTED, GL_OR_REVERSE, and GL_OR_INVERTED.

DESCRIPTION

glLogicOp specifies a logical operation that, when enabled, combines the incoming color index and the color index at the corresponding location in the frame buffer. The logical operation is enabled or disabled with glEnable and glDisable using the symbolic constant GL_LOGIC_OP.

opcode is a symbolic constant chosen from the list below. In the explanation of the logical operations, s represents the incoming color index and d represents the index in the frame buffer. Standard C-language operators are used. As these bitwise operators suggest, the logical operation is applied independently to each bit pair of the source and destination indices.

NOTES

Logical pixel operations are not applied to RGBA color buffers.

When more than one color index buffer is enabled for drawing, logical operations are done separately for each enabled buffer, using for the destination index the contents of that buffer (see glDrawBuffer).

opcode mst be one of the sixteen accepted values. Other values result in an error.

ERRORS

GL_INVALID_ENUM is generated if opcode is not an accepted value.

GL_INVALID_OPERATION is generated if glLogicOp is called between a call to glBegin and the corresponding call to glEnd.

ASSOCIATED GETS

glGet with argument GL_LOGIC_OP_MODE
glIsEnabled with argument GL_LOGIC_OP