/**
 * Copyright (c) 2017-2021 mol* contributors, licensed under MIT, See LICENSE file for more info.
 *
 * @author Alexander Rose <alexander.rose@weirdbyte.de>
 * @author Michael Krone <michael.krone@uni-tuebingen.de>
 */
export declare const directVolume_frag = "\nprecision highp float;\nprecision highp int;\n\n#include common\n#include light_frag_params\n\n#if dClipObjectCount != 0\n    uniform int uClipObjectType[dClipObjectCount];\n    uniform bool uClipObjectInvert[dClipObjectCount];\n    uniform vec3 uClipObjectPosition[dClipObjectCount];\n    uniform vec4 uClipObjectRotation[dClipObjectCount];\n    uniform vec3 uClipObjectScale[dClipObjectCount];\n#endif\n#include common_clip\n\n#include read_from_texture\n#include texture3d_from_1d_trilinear\n#include texture3d_from_2d_nearest\n#include texture3d_from_2d_linear\n\nuniform mat4 uProjection, uTransform, uModelView, uModel, uView;\nuniform vec3 uCameraDir;\n\nuniform sampler2D tDepth;\nuniform vec2 uDrawingBufferSize;\n\nvarying vec3 vOrigPos;\nvarying float vInstance;\nvarying vec4 vBoundingSphere;\nvarying mat4 vTransform;\n\nuniform mat4 uInvView;\nuniform vec2 uIsoValue;\nuniform vec3 uGridDim;\nuniform vec3 uBboxSize;\nuniform sampler2D tTransferTex;\nuniform float uTransferScale;\nuniform float uStepScale;\nuniform float uJumpLength;\n\nuniform int uObjectId;\nuniform int uVertexCount;\nuniform int uInstanceCount;\nuniform int uGroupCount;\n\nuniform vec3 uHighlightColor;\nuniform vec3 uSelectColor;\nuniform float uHighlightStrength;\nuniform float uSelectStrength;\nuniform int uMarkerPriority;\n\n#if defined(dMarkerType_uniform)\n    uniform float uMarker;\n#elif defined(dMarkerType_groupInstance)\n    uniform vec2 uMarkerTexDim;\n    uniform sampler2D tMarker;\n#endif\n\nuniform float uFogNear;\nuniform float uFogFar;\nuniform vec3 uFogColor;\n\nuniform float uAlpha;\nuniform float uPickingAlphaThreshold;\nuniform bool uTransparentBackground;\n\nuniform float uInteriorDarkening;\nuniform bool uInteriorColorFlag;\nuniform vec3 uInteriorColor;\nbool interior;\n\nuniform bool uRenderWboit;\n\nuniform float uNear;\nuniform float uFar;\nuniform float uIsOrtho;\n\nuniform vec3 uCellDim;\nuniform vec3 uCameraPosition;\nuniform mat4 uCartnToUnit;\n\n#if __VERSION__ != 100\n    // for webgl1 this is given as a 'define'\n    uniform int uMaxSteps;\n#endif\n\n#if defined(dGridTexType_2d)\n    precision highp sampler2D;\n    uniform sampler2D tGridTex;\n    uniform vec3 uGridTexDim;\n#elif defined(dGridTexType_3d)\n    precision highp sampler3D;\n    uniform sampler3D tGridTex;\n#endif\n\n#if defined(dRenderVariant_color)\n    #if defined(dColorType_uniform)\n        uniform vec3 uColor;\n    #elif defined(dColorType_texture)\n        uniform vec2 uColorTexDim;\n        uniform sampler2D tColor;\n    #endif\n\n    #ifdef dOverpaint\n        varying vec4 vOverpaint;\n        uniform vec2 uOverpaintTexDim;\n        uniform sampler2D tOverpaint;\n    #endif\n#endif\n\n#if defined(dGridTexType_2d)\n    vec4 textureVal(vec3 pos) {\n        return texture3dFrom2dLinear(tGridTex, pos + (vec3(0.5, 0.5, 0.0) / uGridDim), uGridDim, uGridTexDim.xy);\n    }\n    vec4 textureGroup(vec3 pos) {\n        return texture3dFrom2dNearest(tGridTex, pos + (vec3(0.5, 0.5, 0.0) / uGridDim), uGridDim, uGridTexDim.xy);\n    }\n#elif defined(dGridTexType_3d)\n    vec4 textureVal(vec3 pos) {\n        return texture(tGridTex, pos + (vec3(0.5) / uGridDim));\n    }\n    vec4 textureGroup(vec3 pos) {\n        return texelFetch(tGridTex, ivec3(pos * uGridDim), 0);\n    }\n#endif\n\nfloat calcDepth(const in vec3 pos) {\n    vec2 clipZW = pos.z * uProjection[2].zw + uProjection[3].zw;\n    return 0.5 + 0.5 * clipZW.x / clipZW.y;\n}\n\nvec4 transferFunction(float value) {\n    return texture2D(tTransferTex, vec2(value, 0.0));\n}\n\nfloat getDepth(const in vec2 coords) {\n    #ifdef depthTextureSupport\n        if (!uRenderWboit) {\n            // in case of opaque volumes (and depth texture support)\n            return texture2D(tDepth, coords).r;\n        } else {\n            return unpackRGBAToDepth(texture2D(tDepth, coords));\n        }\n    #else\n        return unpackRGBAToDepth(texture2D(tDepth, coords));\n    #endif\n}\n\nconst float gradOffset = 0.5;\n\nvec3 v3m4(vec3 p, mat4 m) {\n    return (m * vec4(p, 1.0)).xyz;\n}\n\nfloat preFogAlphaBlended = 0.0;\n\nvec4 raymarch(vec3 startLoc, vec3 step, vec3 rayDir) {\n    #if defined(dRenderVariant_color) && !defined(dIgnoreLight)\n        mat3 normalMatrix = transpose3(inverse3(mat3(uModelView * vTransform)));\n    #endif\n    mat4 cartnToUnit = uCartnToUnit * inverse4(vTransform);\n    #if defined(dClipVariant_pixel) && dClipObjectCount != 0\n        mat4 modelTransform = uModel * vTransform * uTransform;\n    #endif\n    mat4 modelViewTransform = uModelView * vTransform * uTransform;\n\n    vec3 scaleVol = vec3(1.0) / uGridDim;\n    vec3 pos = startLoc;\n    vec4 cell;\n    float prevValue = -1.0;\n    float value = 0.0;\n    vec4 src = vec4(0.0);\n    vec4 dst = vec4(0.0);\n    bool hit = false;\n    float fragmentDepth;\n\n    vec3 posMin = vec3(0.0);\n    vec3 posMax = vec3(1.0) - vec3(1.0) / uGridDim;\n\n    vec3 unitPos;\n    vec3 isoPos;\n\n    vec3 nextPos;\n    float nextValue;\n\n    vec3 color = vec3(0.45, 0.55, 0.8);\n    vec3 gradient = vec3(1.0);\n    vec3 dx = vec3(gradOffset * scaleVol.x, 0.0, 0.0);\n    vec3 dy = vec3(0.0, gradOffset * scaleVol.y, 0.0);\n    vec3 dz = vec3(0.0, 0.0, gradOffset * scaleVol.z);\n\n    float maxDist = min(vBoundingSphere.w * 2.0, uFar - uNear);\n    float maxDistSq = maxDist * maxDist;\n\n    for (int i = 0; i < uMaxSteps; ++i) {\n        // break when beyond bounding-sphere or far-plane\n        vec3 distVec = startLoc - pos;\n        if (dot(distVec, distVec) > maxDistSq) break;\n\n        unitPos = v3m4(pos, cartnToUnit);\n\n        // continue when outside of grid\n        if (unitPos.x > posMax.x || unitPos.y > posMax.y || unitPos.z > posMax.z ||\n            unitPos.x < posMin.x || unitPos.y < posMin.y || unitPos.z < posMin.z\n        ) {\n            if (hit) break;\n            prevValue = value;\n            pos += step;\n            continue;\n        }\n\n        cell = textureVal(unitPos);\n        value = cell.a; // current voxel value\n\n        if (uJumpLength > 0.0 && value < 0.01) {\n            nextPos = pos + rayDir * uJumpLength;\n            nextValue = textureVal(v3m4(nextPos, cartnToUnit)).a;\n            if (nextValue < 0.01) {\n                prevValue = nextValue;\n                pos = nextPos;\n                continue;\n            }\n        }\n\n        #if defined(dRenderMode_isosurface)\n            if (prevValue > 0.0 && ( // there was a prev Value\n                (prevValue < uIsoValue.x && value > uIsoValue.x) || // entering isosurface\n                (prevValue > uIsoValue.x && value < uIsoValue.x) // leaving isosurface\n            )) {\n                isoPos = v3m4(mix(pos - step, pos, ((prevValue - uIsoValue.x) / ((prevValue - uIsoValue.x) - (value - uIsoValue.x)))), cartnToUnit);\n\n                vec4 mvPosition = modelViewTransform * vec4(isoPos * uGridDim, 1.0);\n\n                #if defined(dClipVariant_pixel) && dClipObjectCount != 0\n                    vec3 vModelPosition = v3m4(isoPos * uGridDim, modelTransform);\n                    if (clipTest(vec4(vModelPosition, 0.0), 0)) {\n                        prevValue = value;\n                        pos += step;\n                        continue;\n                    }\n                #endif\n\n                float depth = calcDepth(mvPosition.xyz);\n                if (depth > getDepth(gl_FragCoord.xy / uDrawingBufferSize))\n                    break;\n\n                #ifdef enabledFragDepth\n                    if (!hit) {\n                        gl_FragDepthEXT = depth;\n                    }\n                #endif\n\n                #if defined(dRenderVariant_pickObject)\n                    return vec4(encodeFloatRGB(float(uObjectId)), 1.0);\n                #elif defined(dRenderVariant_pickInstance)\n                    return vec4(encodeFloatRGB(vInstance), 1.0);\n                #elif defined(dRenderVariant_pickGroup)\n                    #ifdef dPackedGroup\n                        return vec4(textureGroup(floor(isoPos * uGridDim + 0.5) / uGridDim).rgb, 1.0);\n                    #else\n                        vec3 g = floor(isoPos * uGridDim + 0.5);\n                        return vec4(encodeFloatRGB(g.z + g.y * uGridDim.z + g.x * uGridDim.z * uGridDim.y), 1.0);\n                    #endif\n                #elif defined(dRenderVariant_depth)\n                    #ifdef enabledFragDepth\n                        return packDepthToRGBA(gl_FragDepthEXT);\n                    #else\n                        return packDepthToRGBA(depth);\n                    #endif\n                #elif defined(dRenderVariant_color)\n                    #ifdef dPackedGroup\n                        float group = decodeFloatRGB(textureGroup(floor(isoPos * uGridDim + 0.5) / uGridDim).rgb);\n                    #else\n                        vec3 g = floor(isoPos * uGridDim + 0.5);\n                        float group = g.z + g.y * uGridDim.z + g.x * uGridDim.z * uGridDim.y;\n                    #endif\n\n                    #if defined(dColorType_uniform)\n                        color = uColor;\n                    #elif defined(dColorType_instance)\n                        color = readFromTexture(tColor, vInstance, uColorTexDim).rgb;\n                    #elif defined(dColorType_group)\n                        color = readFromTexture(tColor, group, uColorTexDim).rgb;\n                    #elif defined(dColorType_groupInstance)\n                        color = readFromTexture(tColor, vInstance * float(uGroupCount) + group, uColorTexDim).rgb;\n                    #elif defined(dColorType_vertex)\n                        color = texture3dFrom1dTrilinear(tColor, isoPos, uGridDim, uColorTexDim, 0.0).rgb;\n                    #elif defined(dColorType_vertexInstance)\n                        color = texture3dFrom1dTrilinear(tColor, isoPos, uGridDim, uColorTexDim, vInstance * float(uVertexCount)).rgb;\n                    #endif\n\n                    // handle flipping and negative isosurfaces\n                    #ifdef dFlipSided\n                        bool flipped = value < uIsoValue.y; // flipped\n                    #else\n                        bool flipped = value > uIsoValue.y;\n                    #endif\n                    interior = value < uIsoValue.x && flipped;\n                    #ifndef dDoubleSided\n                        if (interior) {\n                            prevValue = value;\n                            pos += step;\n                            continue;\n                        }\n                    #endif\n                    vec3 vViewPosition = mvPosition.xyz;\n                    vec4 material = vec4(color, uAlpha);\n\n                    #ifdef dIgnoreLight\n                        gl_FragColor = material;\n                    #else\n                        #if defined(dFlatShaded)\n                            // nearest grid point\n                            isoPos = floor(isoPos * uGridDim + 0.5) / uGridDim;\n                        #endif\n                        #ifdef dPackedGroup\n                            // compute gradient by central differences\n                            gradient.x = textureVal(isoPos - dx).a - textureVal(isoPos + dx).a;\n                            gradient.y = textureVal(isoPos - dy).a - textureVal(isoPos + dy).a;\n                            gradient.z = textureVal(isoPos - dz).a - textureVal(isoPos + dz).a;\n                        #else\n                            gradient = textureVal(isoPos).xyz * 2.0 - 1.0;\n                        #endif\n                        vec3 normal = -normalize(normalMatrix * normalize(gradient));\n                        normal = normal * (float(flipped) * 2.0 - 1.0);\n                        normal = normal * -(float(interior) * 2.0 - 1.0);\n                        #include apply_light_color\n                    #endif\n\n                    #if defined(dMarkerType_uniform)\n                        float marker = uMarker;\n                    #elif defined(dMarkerType_groupInstance)\n                        float marker = readFromTexture(tMarker, vInstance * float(uGroupCount) + group, uMarkerTexDim).a;\n                        marker = floor(marker * 255.0 + 0.5); // rounding required to work on some cards on win\n                    #endif\n                    #include apply_interior_color\n                    #include apply_marker_color\n\n                    preFogAlphaBlended = (1.0 - preFogAlphaBlended) * gl_FragColor.a + preFogAlphaBlended;\n                    fragmentDepth = depth;\n                    #include apply_fog\n\n                    src = gl_FragColor;\n\n                    if (!uTransparentBackground) {\n                        // done in 'apply_fog' otherwise\n                        src.rgb *= src.a;\n                    }\n                    dst = (1.0 - dst.a) * src + dst; // standard blending\n                #endif\n\n                #ifdef dSingleLayer\n                    break;\n                #endif\n\n                hit = true;\n            }\n            prevValue = value;\n        #elif defined(dRenderMode_volume)\n            vec4 mvPosition = modelViewTransform * vec4(unitPos * uGridDim, 1.0);\n            if (calcDepth(mvPosition.xyz) > getDepth(gl_FragCoord.xy / uDrawingBufferSize))\n                break;\n\n            #if defined(dClipVariant_pixel) && dClipObjectCount != 0\n                vec3 vModelPosition = v3m4(unitPos * uGridDim, modelTransform);\n                if (clipTest(vec4(vModelPosition, 0.0), 0)) {\n                    prevValue = value;\n                    pos += step;\n                    continue;\n                }\n            #endif\n\n            #if defined(dRenderVariant_color)\n                vec3 vViewPosition = mvPosition.xyz;\n                vec4 material = transferFunction(value);\n\n                #ifdef dIgnoreLight\n                    gl_FragColor.rgb = material.rgb;\n                #else\n                    if (material.a >= 0.01) {\n                        #ifdef dPackedGroup\n                            // compute gradient by central differences\n                            gradient.x = textureVal(unitPos - dx).a - textureVal(unitPos + dx).a;\n                            gradient.y = textureVal(unitPos - dy).a - textureVal(unitPos + dy).a;\n                            gradient.z = textureVal(unitPos - dz).a - textureVal(unitPos + dz).a;\n                        #else\n                            gradient = cell.xyz * 2.0 - 1.0;\n                        #endif\n                        vec3 normal = -normalize(normalMatrix * normalize(gradient));\n                        #include apply_light_color\n                    } else {\n                        gl_FragColor.rgb = material.rgb;\n                    }\n                #endif\n\n                gl_FragColor.a = material.a * uAlpha * uTransferScale;\n\n                #if defined(dMarkerType_uniform)\n                    float marker = uMarker;\n                #elif defined(dMarkerType_groupInstance)\n                    #ifdef dPackedGroup\n                        float group = decodeFloatRGB(textureGroup(floor(unitPos * uGridDim + 0.5) / uGridDim).rgb);\n                    #else\n                        vec3 g = floor(unitPos * uGridDim + 0.5);\n                        float group = g.z + g.y * uGridDim.z + g.x * uGridDim.z * uGridDim.y;\n                    #endif\n                    float marker = readFromTexture(tMarker, vInstance * float(uGroupCount) + group, uMarkerTexDim).a;\n                    marker = floor(marker * 255.0 + 0.5); // rounding required to work on some cards on win\n                #endif\n                #include apply_marker_color\n\n                preFogAlphaBlended = (1.0 - preFogAlphaBlended) * gl_FragColor.a + preFogAlphaBlended;\n                fragmentDepth = calcDepth(mvPosition.xyz);\n                #include apply_fog\n\n                src = gl_FragColor;\n\n                if (!uTransparentBackground) {\n                    // done in 'apply_fog' otherwise\n                    src.rgb *= src.a;\n                }\n                dst = (1.0 - dst.a) * src + dst; // standard blending\n            #endif\n        #endif\n\n        // break if the color is opaque enough\n        if (dst.a > 0.95)\n            break;\n\n        pos += step;\n    }\n\n    #if defined(dRenderMode_isosurface) && defined(enabledFragDepth)\n        // ensure depth is written everywhere\n        if (!hit)\n            gl_FragDepthEXT = 1.0;\n    #endif\n\n    return dst;\n}\n\n// TODO: support float texture for higher precision values???\n// TODO: support clipping exclusion texture support\n\nvoid main() {\n    if (gl_FrontFacing)\n        discard;\n\n    #ifdef dRenderVariant_marking\n        // not supported\n        discard;\n    #endif\n\n    #if defined(dRenderVariant_pick) || defined(dRenderVariant_depth)\n        #if defined(dRenderMode_volume)\n            // always ignore pick & depth for volume\n            discard;\n        #elif defined(dRenderMode_isosurface)\n            if (uAlpha < uPickingAlphaThreshold)\n                discard; // ignore so the element below can be picked\n        #endif\n    #endif\n\n    vec3 rayDir = mix(normalize(vOrigPos - uCameraPosition), uCameraDir, uIsOrtho);\n    vec3 step = rayDir * uStepScale;\n\n    float boundingSphereNear = distance(vBoundingSphere.xyz, uCameraPosition) - vBoundingSphere.w;\n    float d = max(uNear, boundingSphereNear) - mix(0.0, distance(vOrigPos, uCameraPosition), uIsOrtho);\n    vec3 start = mix(uCameraPosition, vOrigPos, uIsOrtho) + (d * rayDir);\n    gl_FragColor = raymarch(start, step, rayDir);\n\n    #if defined(dRenderVariant_pick) || defined(dRenderVariant_depth)\n        // discard when nothing was hit\n        if (gl_FragColor == vec4(0.0))\n            discard;\n    #endif\n\n    #if defined(dRenderVariant_color)\n        #if defined(dRenderMode_isosurface) && defined(enabledFragDepth)\n            float fragmentDepth = gl_FragDepthEXT;\n        #else\n            float fragmentDepth = calcDepth((uModelView * vec4(start, 1.0)).xyz);\n        #endif\n        float preFogAlpha = clamp(preFogAlphaBlended, 0.0, 1.0);\n        interior = false;\n        #include wboit_write\n    #endif\n}\n";