grid.yaml

import:
    - ../space/tile.yaml

styles:
    patterns-grid:
        doc:
            author: 
                name: Patricio Gonzalez Vivo
                twitter: patriciogv
            version: 0.0.1
            tangram-version: 0.0.7
            licence: MIT
            description: |  
                Collection of functions to draw grids. To learn more about patterns check [this chapter from the Book of Shaders](https://thebookofshaders.com/09/)    
            examples:
                blueprint:
                    url: https://tangrams.github.io/tangram-sandbox/styles/blueprint.yaml
                    img: https://tangrams.github.io/tangram-sandbox/styles/blueprint.png
                    lines: 75-76
                grain:
                    url: https://tangrams.github.io/tangram-sandbox/styles/grain.yaml
                    img: https://tangrams.github.io/tangram-sandbox/styles/grain.png
                    lines: 15
        mix: [space-tile]
        shaders:
            blocks:
                global: |
                    // Draw a grid in the space a specific resolution and pressition
                    bool grid (vec2 st, float res, float press) {
                        vec2 grid = fract(st*res);
                        return grid.x < res*press || grid.y < res*press;
                    }
                    //
                    // Draw a grid in the space a specific resolution
                    bool grid (vec2 st, float res) {
                        return grid(st, res, 1.0);
                    }

                    //
                    // Draw a grid in 45 degress with a specific width
                    float diagonalGrid(vec2 st, float width){
                        return step(.5,max( smoothstep(st.x-width,st.x,st.y)*(1.-smoothstep(st.x,st.x+width,st.y)),
                                            smoothstep(st.x-width,st.x,1.0-st.y)*(1.-smoothstep(st.x,st.x+width,1.0-st.y))));
                    }

                    // Draw a grid using tile coordenates in a specific resolution
                    float tileGrid (float res) {
                        vec2 st = getTileCoords()*100.*res;
                        float pct = 0.0;
                        float press = 0.4+(1.0-fract(u_map_position.z))*0.1;
                        if (grid(st,0.01,press)) pct += 0.5;
                        if (grid(st,0.1,press)) pct += 0.1;
                        return pct;
                    }

                    // Draw two grid that smoothly interpolates acording to zooms
                    float tileGrid() { 
                        return mix(tileGrid(1.),tileGrid(2.),fract(u_map_position.z)); 
                    }