Add attrib() method to PGraphics #2963
Description
The shader API is currently limited to handle only the following vertex attributes:
- position
- color (fill, stroke)
- texture coordinates
- normal vector
- material properties (ambient, specular, and emissive colors, shininess)
After the Denver retreat, it has been decided to add the "attrib" function to the PGraphics API to let users specify generic per-vertex attributes. This function tentatively has the following signature:
void attrib(String name, float... values);
void attrib(String name, int... values);
void attrib(String name, boolean... values);Usage example:
float angle;
void setup() {
size(400, 400, P3D);
noStroke();
}
void draw() {
background(0);
pointLight(200, 200, 200, width/2, height/2, -200);
translate(width/2, height/2);
rotateY(angle);
beginShape(QUADS);
normal(0, 0, 1);
fill(50, 50, 200);
// A scalar attribute named brightness, affecting the next two vertices
attrib("brightness", 0.1);
// A vector attribute named tangent, affecting the first vertex
attrib("tangent", 0.1, 0.8, 0.1);
vertex(-100, +100);
// Another tangent vector, affecting the second vertex
attrib("tangent", -0.3, 1, 0);
vertex(+100, +100);
fill(200, 50, 50);
// A new brightness value, affecting the last two vertices
attrib("brightness", 0.5);
attrib("tangent", 0.5, 0.5, 0.1);
vertex(+100, -100);
attrib("tangent", 0.1, -0.9, 0);
vertex(-100, -100);
endShape();
angle += 0.01;
} The first time attrib() is called with a new attribute name, the renderer needs to automatically initialize all the corresponding internal variables (VBO's and backing arrays) needed to handle this attribute. The tessellator also needs to interpolate the values for the attributes, in the same way it now does for the built-in attributes.
Reactions are currently unavailable