cesium/Source/Shaders/PolylineCommon.js

CesiumJS is a JavaScript library for creating 3D globes and 2D maps in a web browser without a plugin.

//This file is automatically rebuilt by the Cesium build process.
export default "void clipLineSegmentToNearPlane(\n\
    vec3 p0,\n\
    vec3 p1,\n\
    out vec4 positionWC,\n\
    out bool clipped,\n\
    out bool culledByNearPlane)\n\
{\n\
    culledByNearPlane = false;\n\
    clipped = false;\n\
\n\
    vec3 p1ToP0 = p1 - p0;\n\
    float magnitude = length(p1ToP0);\n\
    vec3 direction = normalize(p1ToP0);\n\
    float endPoint0Distance =  -(czm_currentFrustum.x + p0.z);\n\
    float denominator = -direction.z;\n\
\n\
    if (endPoint0Distance < 0.0 && abs(denominator) < czm_epsilon7)\n\
    {\n\
        culledByNearPlane = true;\n\
    }\n\
    else if (endPoint0Distance < 0.0 && abs(denominator) > czm_epsilon7)\n\
    {\n\
        // t = (-plane distance - dot(plane normal, ray origin)) / dot(plane normal, ray direction)\n\
        float t = (czm_currentFrustum.x + p0.z) / denominator;\n\
        if (t < 0.0 || t > magnitude)\n\
        {\n\
            culledByNearPlane = true;\n\
        }\n\
        else\n\
        {\n\
            p0 = p0 + t * direction;\n\
            clipped = true;\n\
        }\n\
    }\n\
\n\
    positionWC = czm_eyeToWindowCoordinates(vec4(p0, 1.0));\n\
}\n\
\n\
vec4 getPolylineWindowCoordinatesEC(vec4 positionEC, vec4 prevEC, vec4 nextEC, float expandDirection, float width, bool usePrevious, out float angle)\n\
{\n\
    vec4 endPointWC, p0, p1;\n\
    bool culledByNearPlane, clipped;\n\
\n\
#ifdef POLYLINE_DASH\n\
    // Compute the window coordinates of the points.\n\
    vec4 positionWindow = czm_eyeToWindowCoordinates(positionEC);\n\
    vec4 previousWindow = czm_eyeToWindowCoordinates(prevEC);\n\
    vec4 nextWindow = czm_eyeToWindowCoordinates(nextEC);\n\
\n\
    // Determine the relative screen space direction of the line.\n\
    vec2 lineDir;\n\
    if (usePrevious) {\n\
        lineDir = normalize(positionWindow.xy - previousWindow.xy);\n\
    }\n\
    else {\n\
        lineDir = normalize(nextWindow.xy - positionWindow.xy);\n\
    }\n\
    angle = atan(lineDir.x, lineDir.y) - 1.570796327; // precomputed atan(1,0)\n\
\n\
    // Quantize the angle so it doesn't change rapidly between segments.\n\
    angle = floor(angle / czm_piOverFour + 0.5) * czm_piOverFour;\n\
#endif\n\
\n\
    clipLineSegmentToNearPlane(prevEC.xyz, positionEC.xyz, p0, clipped, culledByNearPlane);\n\
    clipLineSegmentToNearPlane(nextEC.xyz, positionEC.xyz, p1, clipped, culledByNearPlane);\n\
    clipLineSegmentToNearPlane(positionEC.xyz, usePrevious ? prevEC.xyz : nextEC.xyz, endPointWC, clipped, culledByNearPlane);\n\
\n\
    if (culledByNearPlane)\n\
    {\n\
        return vec4(0.0, 0.0, 0.0, 1.0);\n\
    }\n\
\n\
    vec2 prevWC = normalize(p0.xy - endPointWC.xy);\n\
    vec2 nextWC = normalize(p1.xy - endPointWC.xy);\n\
\n\
    float expandWidth = width * 0.5;\n\
    vec2 direction;\n\
\n\
#ifdef CLIP_POLYLINE\n\
    if (clipped)\n\
    {\n\
        if (prevEC.z - positionEC.z < 0.0)\n\
        {\n\
            direction = vec2(prevWC.y, -prevWC.x);\n\
        }\n\
        else\n\
        {\n\
            direction = vec2(-prevWC.y, prevWC.x);\n\
        }\n\
    }\n\
    else\n\
#endif\n\
    if (czm_equalsEpsilon(prevEC.xyz - positionEC.xyz, vec3(0.0), czm_epsilon1) || czm_equalsEpsilon(prevWC, -nextWC, czm_epsilon1))\n\
    {\n\
        direction = vec2(-nextWC.y, nextWC.x);\n\
    }\n\
    else if (czm_equalsEpsilon(nextEC.xyz - positionEC.xyz, vec3(0.0), czm_epsilon1))\n\
    {\n\
        direction = vec2(prevWC.y, -prevWC.x);\n\
    }\n\
    else\n\
    {\n\
        vec2 normal = vec2(-nextWC.y, nextWC.x);\n\
        direction = normalize((nextWC + prevWC) * 0.5);\n\
        if (dot(direction, normal) < 0.0)\n\
        {\n\
            direction = -direction;\n\
        }\n\
\n\
        // The sine of the angle between the two vectors is given by the formula\n\
        //         |a x b| = |a||b|sin(theta)\n\
        // which is\n\
        //     float sinAngle = length(cross(vec3(direction, 0.0), vec3(nextWC, 0.0)));\n\
        // Because the z components of both vectors are zero, the x and y coordinate will be zero.\n\
        // Therefore, the sine of the angle is just the z component of the cross product.\n\
        float sinAngle = abs(direction.x * nextWC.y - direction.y * nextWC.x);\n\
        expandWidth = clamp(expandWidth / sinAngle, 0.0, width * 2.0);\n\
    }\n\
\n\
    vec2 offset = direction * expandDirection * expandWidth * czm_pixelRatio;\n\
    return vec4(endPointWC.xy + offset, -endPointWC.z, 1.0);\n\
}\n\
\n\
vec4 getPolylineWindowCoordinates(vec4 position, vec4 previous, vec4 next, float expandDirection, float width, bool usePrevious, out float angle)\n\
{\n\
    vec4 positionEC = czm_modelViewRelativeToEye * position;\n\
    vec4 prevEC = czm_modelViewRelativeToEye * previous;\n\
    vec4 nextEC = czm_modelViewRelativeToEye * next;\n\
    return getPolylineWindowCoordinatesEC(positionEC, prevEC, nextEC, expandDirection, width, usePrevious, angle);\n\
}\n\
";