geometry.yaml

styles:
    terrain-geometry:
        doc:
            author: 
                name: Patricio Gonzalez Vivo
                twitter: patriciogv
            version: 0.0.1
            tangram-version: 0.0.7
            licence: MIT
        raster: custom
        shaders:
            defines:
                TERRAIN_TEXTURE_INDEX: 0
                TERRAIN_ZOFFSET: 0.
            blocks:
                global: |
                    #ifdef TANGRAM_VERTEX_SHADER
                    uniform sampler2D u_rasters[TANGRAM_NUM_RASTER_SOURCES];
                    uniform vec2 u_raster_sizes[TANGRAM_NUM_RASTER_SOURCES];
                    uniform vec3 u_raster_offsets[TANGRAM_NUM_RASTER_SOURCES];
                    #define adjustRasterUV(raster_index, uv) ((uv) * u_raster_offsets[raster_index].z + u_raster_offsets[raster_index].xy)
                    #define currentRasterUV(raster_index) (adjustRasterUV(raster_index, v_modelpos_base_zoom.xy))
                    #define currentRasterPixel(raster_index) (currentRasterUV(raster_index) * rasterPixelSize(raster_index))
                    #define sampleRaster(raster_index) (texture2D(u_rasters[raster_index], currentRasterUV(raster_index)))
                    #define sampleRasterAtPixel(raster_index, pixel) (texture2D(u_rasters[raster_index], adjustRasterUV(raster_index, (pixel) / rasterPixelSize(raster_index))))
                    #define rasterPixelSize(raster_index) (u_raster_sizes[raster_index])
                    #endif

                    float getHeight() {
                        float h = sampleRaster(int(TERRAIN_TEXTURE_INDEX)).a;
                        if (h != 0.0) {
                            return (1.-h)*10000.;
                        } else {
                            return 0.0;
                        }
                    }
                position: |
                    position.z += TERRAIN_ZOFFSET*u_meters_per_pixel;
                    position.z += getHeight();