@cesium/engine
Version:
CesiumJS is a JavaScript library for creating 3D globes and 2D maps in a web browser without a plugin.
102 lines (101 loc) • 4.23 kB
JavaScript
//This file is automatically rebuilt by the Cesium build process.
export default "in vec2 v_textureCoordinates;\n\
\n\
uniform int u_polygonsLength;\n\
uniform int u_extentsLength;\n\
uniform highp sampler2D u_polygonTexture;\n\
uniform highp sampler2D u_extentsTexture;\n\
\n\
int getPolygonIndex(float dimension, vec2 coord) {\n\
vec2 uv = coord.xy * dimension;\n\
return int(floor(uv.y) * dimension + floor(uv.x));\n\
}\n\
\n\
vec2 getLookupUv(ivec2 dimensions, int i) {\n\
int pixY = i / dimensions.x;\n\
int pixX = i - (pixY * dimensions.x);\n\
float pixelWidth = 1.0 / float(dimensions.x);\n\
float pixelHeight = 1.0 / float(dimensions.y);\n\
float u = (float(pixX) + 0.5) * pixelWidth; // sample from center of pixel\n\
float v = (float(pixY) + 0.5) * pixelHeight;\n\
return vec2(u, v);\n\
}\n\
\n\
vec4 getExtents(int i) {\n\
return texture(u_extentsTexture, getLookupUv(textureSize(u_extentsTexture, 0), i));\n\
}\n\
\n\
ivec2 getPositionsLengthAndExtentsIndex(int i) {\n\
vec2 uv = getLookupUv(textureSize(u_polygonTexture, 0), i);\n\
vec4 value = texture(u_polygonTexture, uv);\n\
return ivec2(int(value.x), int(value.y));\n\
}\n\
\n\
vec2 getPolygonPosition(int i) {\n\
vec2 uv = getLookupUv(textureSize(u_polygonTexture, 0), i);\n\
return texture(u_polygonTexture, uv).xy;\n\
}\n\
\n\
vec2 getCoordinates(vec2 textureCoordinates, vec4 extents) {\n\
float latitude = mix(extents.x, extents.x + 1.0 / extents.z, textureCoordinates.y);\n\
float longitude = mix(extents.y, extents.y + 1.0 / extents.w, textureCoordinates.x);\n\
return vec2(latitude, longitude);\n\
}\n\
\n\
void main() {\n\
int lastPolygonIndex = 0;\n\
out_FragColor = vec4(1.0);\n\
\n\
// Get the relevant region of the texture\n\
float dimension = float(u_extentsLength);\n\
if (u_extentsLength > 2) {\n\
dimension = ceil(log2(float(u_extentsLength)));\n\
}\n\
int regionIndex = getPolygonIndex(dimension, v_textureCoordinates);\n\
\n\
for (int polygonIndex = 0; polygonIndex < u_polygonsLength; polygonIndex++) {\n\
ivec2 positionsLengthAndExtents = getPositionsLengthAndExtentsIndex(lastPolygonIndex);\n\
int positionsLength = positionsLengthAndExtents.x;\n\
int polygonExtentsIndex = positionsLengthAndExtents.y;\n\
lastPolygonIndex += 1;\n\
\n\
// Only compute signed distance for the relevant part of the atlas\n\
if (polygonExtentsIndex == regionIndex) {\n\
float clipAmount = czm_infinity;\n\
vec4 extents = getExtents(polygonExtentsIndex);\n\
vec2 textureOffset = vec2(mod(float(polygonExtentsIndex), dimension), floor(float(polygonExtentsIndex) / dimension)) / dimension;\n\
vec2 p = getCoordinates((v_textureCoordinates - textureOffset) * dimension, extents);\n\
float s = 1.0;\n\
\n\
// Check each edge for absolute distance\n\
for (int i = 0, j = positionsLength - 1; i < positionsLength; j = i, i++) {\n\
vec2 a = getPolygonPosition(lastPolygonIndex + i);\n\
vec2 b = getPolygonPosition(lastPolygonIndex + j);\n\
\n\
vec2 ab = b - a;\n\
vec2 pa = p - a;\n\
float t = dot(pa, ab) / dot(ab, ab);\n\
t = clamp(t, 0.0, 1.0);\n\
\n\
vec2 pq = pa - t * ab;\n\
float d = length(pq);\n\
\n\
// Inside / outside computation to determine sign\n\
bvec3 cond = bvec3(p.y >= a.y, \n\
p.y < b.y, \n\
ab.x * pa.y > ab.y * pa.x);\n\
if (all(cond) || all(not(cond))) s = -s;\n\
if (abs(d) < abs(clipAmount)) {\n\
clipAmount = d;\n\
}\n\
}\n\
\n\
// Normalize the range to [0,1]\n\
vec4 result = (s * vec4(clipAmount * length(extents.zw))) / 2.0 + 0.5;\n\
// In the case where we've iterated through multiple polygons, take the minimum\n\
out_FragColor = min(out_FragColor, result);\n\
}\n\
\n\
lastPolygonIndex += positionsLength;\n\
}\n\
}";