#fill_keep

1fn fill_keep(inout self, color: vec4) -> vec4

The fill_keep function blends an RGBA color with the current result color of the Sdf2d drawing context, converting the color to pre-multiplied alpha format before blending. It preserves the existing shapes and clipping settings, allowing you to apply additional fills without resetting the drawing state.

#Parameters

• self (inout): A reference to the Sdf2d instance where the blending operation is performed. The function modifies the result field of self in place.
• color (vec4): An RGBA color to be blended with the existing content.

#Returns

• vec4: The updated result color after the blending operation, reflecting the blending of the input color (converted to pre-multiplied alpha) with the existing content.

#Example

1fn pixel(self) -> vec4 {
2    // Create an Sdf2d drawing context for the current viewport.
3    let sdf = Sdf2d::viewport(self.pos * self.rect_size);
4
5    // Draw a rectangle with rounded corners.
6    sdf.box(10.0, 10.0, 80.0, 80.0, 5.0);
7
8    // Apply a semi-transparent red fill, converting to pre-multiplied alpha.
9    sdf.fill_keep(vec4(1.0, 0.0, 0.0, 0.5));
10
11    // Draw another shape without resetting the state.
12    // For example, draw a circle inside the rectangle.
13    sdf.circle(50.0, 50.0, 30.0);
14
15    // Apply a semi-transparent green fill, blending with the previous fills.
16    sdf.fill_keep(vec4(0.0, 1.0, 0.0, 0.5));
17
18    // Return the final color result.
19    return sdf.result;
20}

#Explanation

In this example:

• Create Drawing Context: We initialize an Sdf2d drawing context using the current position (self.pos) and size (self.rect_size) of the viewport.
• Draw Rectangle: We draw a box starting at position (10.0, 10.0) with a width and height of 80.0 units and rounded corners with a radius of 5.0.
• First Fill: Use fill_keep to apply a semi-transparent red color (vec4(1.0, 0.0, 0.0, 0.5)) to the rectangle. The fill_keep function converts the color to pre-multiplied alpha and blends it with the existing content, preserving the current shape and clipping settings.