Problem with beginShape(QUADS)

randomdude

In one of my previous question it was suggested that I use beginShape(QUADS) to display an image. I was unsure what the third and fourth arguments in the vertex(); were after that, so I decided to experiment. This is my code, but it does not display an image at all.

PImage blob;
void setup() {
  size(800,800,P2D);
  blob = loadImage("ASD.jpg");
}
void draw() {
  background(255);
  beginShape(QUADS);
  texture(blob);
  noStroke();
  vertex(100,100,0,0);
  vertex(100,200,0,1);
  vertex(200,200,1,1);
  vertex(200,100,1,0);
  endShape();
}

If someone can explain to me what the 0s and 1s mean as the 3rd and 4th arguments in the vertexes of a beginShape(QUADS) function, that would be awesome!

Chrisir

https://www.processing.org/reference/vertex_.html

u: float: horizontal coordinate for the texture mapping

v: float: vertical coordinate for the texture mapping

koogs

You need to set the texture mode to normalized.

That is probably displaying a quad but you're texturing it with the top left pixel of the image

randomdude

According to the example, the u and v stand for pixel numbers. But the example that koogs gave in my previous question used 1s and 0s. What do the 0s and 1s stand for?

Chrisir

the coordinates used for u and v are specified in relation to the image's size in pixels

relation here could mean 1 = 100 % and 0 = automatic.

reference for vertex

This function is also used to map a texture onto geometry. The texture() function declares the texture to apply to the geometry and the u and v coordinates set define the mapping of this texture to the form. By default, the coordinates used for u and v are specified in relation to the image's size in pixels, but this relation can be changed with textureMode().

https://www.processing.org/reference/vertex_.html

Also see reference textureMode

Sets the coordinate space for texture mapping. The default mode is IMAGE, which refers to the actual coordinates of the image. NORMAL refers to a normalized space of values ranging from 0 to 1. This function only works with the P2D and P3D renderers.

With IMAGE, if an image is 100 x 200 pixels, mapping the image onto the entire size of a quad would require the points (0,0) (100, 0) (100,200) (0,200). The same mapping in NORMAL is (0,0) (1,0) (1,1) (0,1).

https://www.processing.org/reference/textureMode_.html