Mercator - create uniformly distributed dots over map

Question

I have a map in Mercator projection. I know coordinates of corners. I want to render uniformly distributed dots to map.

for (float latDeg = startLatDeg; latDeg <= endLatDeg; latDeg += stepLatDeg){
        for (float lonDeg = startLonDeg; lonDeg <= endLonDeg; lonDeg += stepLonDeg){
            Pixel px = mercator->GetPixels(lonDeg, latDeg);
            map[px.x][px.y] = dot;
        }
    }

where start and end values are corners of map.

This code works for longitude, obviously, since it is uniform and non-distorted. How can I achieve uniformity in latitude? I know, that I cannot use fixed step, but somekind recalculate it based on last latitude. But I dont know how.

Answer 1

It seems to me that, if you want a pattern of evenly spaced points in any map projection, the easiest way is to build your regular grid directly in that projection. This will also be faster, because you only need to transform the coordinates of two points.

Pixel start = mercator->GetPixels(startLonDeg, startLatDeg);
Pixel end = mercator->GetPixels(endLonDeg, endLatDeg);
for (float laty = start.y; laty <= end.y; laty += stepLat){
        for (float lonx = start.x ; lonx <= end.x; lonx += stepLon){

            map[lonx][laty] = dot;
        }
    }