point-state
GPU-accelerated rendering » GPU state

Prev:	triangle-state
Next:	line-state

Vocabulary
gpu.state

Class description
The point-state controls how points are drawn.

•	The size slot contains either a float value specifying a constant pixel radius for all points drawn, or f, in which case the vertex shader determines the size of each point independently.
•	The sprite-origin slot contains either origin-lower-left or origin-upper-left, and determines whether the vertical point sprite coordinates fed to the fragment shader start at zero in the bottom corner and increase upward or start at zero in the upper corner and increase downward.
•	If multisampling is enabled in the multisample-state, the fade-threshold slot specifies a pixel width at which the multisampling implementation may fade the alpha component of point fragments.

See also
<point-state>, get-point-state

Definition

USING: math ;

IN: gpu.state

TUPLE: point-state
    { size maybe{ float } read-only initial: 1.0 } {
        sprite-origin point-sprite-origin read-only initial:
        origin-upper-left
    } { fade-threshold float read-only initial: 1.0 } ;

Methods

USING: accessors combinators gpu.state gpu.state.private kernel
opengl.gl ;

M: point-state set-gpu-state*
    {
        [
            GL_VERTEX_PROGRAM_POINT_SIZE swap size>>
            [ glPointSize glDisable ] [ glEnable ] if*
        ]
        [
            GL_POINT_SPRITE_COORD_ORIGIN swap sprite-origin>>
            gl-point-sprite-origin glPointParameteri
        ]
        [
            GL_POINT_FADE_THRESHOLD_SIZE swap fade-threshold>>
            glPointParameterf
        ]
    } cleave ;