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Texture blit shaders

Texture blit shaders are used to define the behavior of blit calls on a DrawableTexture2D.

Texture blit shaders only have one processing function, the blit() function, which runs for every pixel of the source texture inside the rect given to blit_rect().

Render modes

Render mode	Description
blend_mix	Mix blend mode (alpha is transparency), default.
blend_add	Additive blend mode.
blend_sub	Subtractive blend mode.
blend_mul	Multiplicative blend mode.
blend_disabled	Disable blending, values (including alpha) are written as-is.

Note

There is no premultiplied alpha blend mode for Texture blit shaders.

Built-ins

Values marked as in are read-only. Values marked as out can optionally be written to and will not necessarily contain sensible values. Values marked as inout provide a sensible default value, and can optionally be written to. Samplers cannot be written to so they are not marked.

Global built-ins

Global built-ins are available everywhere, including custom functions.

Built-in	Description
in float TIME	Global time since the engine has started, in seconds. It repeats after every `3,600` seconds (which can be changed with the rollover setting). It's affected by time_scale but not by pausing. If you need a `TIME` variable that is not affected by time scale, add your own global shader uniform and update it each frame.
in float PI	A `PI` constant (`3.141592`). The ratio of a circle's circumference to its diameter and the number of radians in a half turn.
in float TAU	A `TAU` constant (`6.283185`). An equivalent of `PI * 2` and amount of radians in full turn.
in float E	An `E` constant (`2.718281`). Euler's number and a base of the natural logarithm.

Blit built-ins

Source textures

Texture blit shaders have up to 4 source textures bound as inputs. These can be accessed with a sampler2D using hint_blit_source0, hint_blit_source1, hint_blit_source2, and hint_blit_source3.

Built-in	Description
in vec4 FRAGCOORD	Coordinate of pixel center. In screen space. `xy` specifies position in viewport. Upper-left of the viewport is the origin, `(0.0, 0.0)`.
in vec2 UV	UV from the `vertex()` function. This is set to sample all of a source texture.
in vec4 MODULATE	`MODULATE` color passed in by RenderingServer API.
out vec4 COLOR0	Output color to blended with the DrawableTexture target. Initialized to `(0.0, 0.0, 0.0, 0.0)`.
out vec4 COLOR1	Output color to blended with an extra DrawableTexture target. Initialized to `(0.0, 0.0, 0.0, 0.0)`.
out vec4 COLOR2	Output color to blended with an extra DrawableTexture target. Initialized to `(0.0, 0.0, 0.0, 0.0)`.
out vec4 COLOR3	Output color to blended with an extra DrawableTexture target. Initialized to `(0.0, 0.0, 0.0, 0.0)`.

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