trying to graph a mathematical function using a sf::vertexArray that contains sf::Quads, but my quads do not display correctly

user_17566963 0
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In my constructor I have:

function.setPrimitiveType(sf::Quads);
numOfPoints = ((XUpperLimit - XLowerLimit) / .001) * 4;
function.resize(numOfPoints);

and my graph function:

void Window::graphFunction() {
    double YVal;

    for (double XVal = XLowerLimit, index = 0.0; XVal < XUpperLimit; XVal += 0.001, index += 4) {
        YVal = tan(XVal);
        if (YVal > YUpperLimit || YVal < YLowerLimit) {
            continue;
        }

        function[index].position = sf::Vector2f((XOrigin + XVal * 20) - 3.f, (YOrigin - YVal * 20) - 3.f);
        function[index + 1].position = sf::Vector2f((XOrigin + XVal * 20) + 3.f, (YOrigin - YVal * 20) - 3.f);
        function[index + 2].position = sf::Vector2f((XOrigin + XVal * 20) - 3.f, (YOrigin - YVal * 20) + 3.f);
        function[index + 3].position = sf::Vector2f((XOrigin + XVal * 20) + 3.f, (YOrigin - YVal * 20) + 3.f);
    }
}

And it looks like this: Output

You can see each Quad has a triangle cut out of it on the right side instead of it looking like a regular square.

sfml c++
1 Answers

From the documentation:

The 4 points of each quad must be defined consistently, either in clockwise or counter-clockwise order.

The ordering of your points do not satisfy this requirement.

Swapping your first two coordinates would fix this.

Alternately, swapping the last two coordinates would also fix this.

user_162870
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