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Diffstat (limited to 'res/effectlib/tessellationPath.glsllib')
| -rw-r--r-- | res/effectlib/tessellationPath.glsllib | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/res/effectlib/tessellationPath.glsllib b/res/effectlib/tessellationPath.glsllib new file mode 100644 index 0000000..17b87b0 --- /dev/null +++ b/res/effectlib/tessellationPath.glsllib @@ -0,0 +1,183 @@ +/**************************************************************************** +** +** Copyright (C) 2014 NVIDIA Corporation. +** Copyright (C) 2017 The Qt Company Ltd. +** Contact: https://www.qt.io/licensing/ +** +** This file is part of Qt 3D Studio. +** +** $QT_BEGIN_LICENSE:GPL$ +** Commercial License Usage +** Licensees holding valid commercial Qt licenses may use this file in +** accordance with the commercial license agreement provided with the +** Software or, alternatively, in accordance with the terms contained in +** a written agreement between you and The Qt Company. For licensing terms +** and conditions see https://www.qt.io/terms-conditions. For further +** information use the contact form at https://www.qt.io/contact-us. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 3 or (at your option) any later version +** approved by the KDE Free Qt Foundation. The licenses are as published by +** the Free Software Foundation and appearing in the file LICENSE.GPL3 +** included in the packaging of this file. Please review the following +** information to ensure the GNU General Public License requirements will +** be met: https://www.gnu.org/licenses/gpl-3.0.html. +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#ifndef TESSELLATION_PATH_GLSLLIB +#define TESSELLATION_PATH_GLSLLIB + + +#if TESSELLATION_CONTROL_SHADER +layout (vertices = 5) out; + +void tessShader ( in float edgeTessAmount, float innerTessAmount ) +{ + gl_TessLevelOuter[0] = innerTessAmount; + gl_TessLevelOuter[1] = edgeTessAmount; + gl_TessLevelOuter[2] = innerTessAmount; + gl_TessLevelOuter[3] = edgeTessAmount; + + gl_TessLevelInner[0] = edgeTessAmount / 2.0; + gl_TessLevelInner[1] = innerTessAmount; +} + +#endif + +#if TESSELLATION_EVALUATION_SHADER +layout (quads, equal_spacing, cw) in; + +vec2 getTangent(vec2 p0, vec2 p1, vec2 p2, vec2 p3, float t) +{ + // derivative + float dbt0 = -3.0 * (1.0 - t) * (1.0 - t); + float dbt1 = 3.0 * (1.0 - t) * (1.0 - 3.0 * t); + float dbt2 = 3.0 * t * (2.0 - 3.0 * t); + float dbt3 = 3.0 * t * t; + + // tangent on curve + return normalize( dbt0 * p0 + dbt1 * p1 + dbt2 * p2 + dbt3 * p3 ); +} +//An exact cross product would involve normalizing dx,dy. Since +//this algorithm needs merely the sign, normalization is not necessary. +float roughCrossProd( vec2 prev, vec2 point, vec2 next ) +{ + vec2 inDxDy = point - prev; + vec2 outDxDy = next - point; + return inDxDy.x * outDxDy.y - inDxDy.y * outDxDy.x; +} + +//The incoming corss product tells us both if we should do a seam merge +//and if the merge is above or below point in gl_TessCoord.y space; we know the +//anchor point is at .5 gl_TessCoord.y space. +vec3 computeAdjoiningFactors( float cross, vec2 adjoining, vec2 point, float tessY ) +{ + vec3 retval = vec3( 0.0, 0.0, 0.0 ); + float multiplier = cross < 0.0 ? 1.0 : -1.0; + float weight = abs(cross) > 0.001 ? multiplier * ( ( tessY - .5 )/ .5 ) : 0.0; + retval.z = weight > 0.0 ? 1.0 : 0.0; + retval.xy = mix( point, adjoining, weight ); + return retval; +} + +#define NO_TAPER 0 +#define BEGIN_TAPER 1 +#define END_TAPER 2 + +//Tapering is done by interpolating the path width somewhat cleverly. +float getTaperResult( float inIncomingValue, float inBeginValue, float inEndValue, vec2 taperData, uint inMode ) +{ + float mixInfo = mix( taperData.x, taperData.y, gl_TessCoord.x ); + float theValueMixer = inMode == BEGIN_TAPER ? inBeginValue : inEndValue; + return mix( theValueMixer, inIncomingValue, mixInfo ); +} + +uniform vec2 beginTaperInfo; +uniform vec2 endTaperInfo; + +struct STessShaderResult +{ + vec3 m_Position; + vec2 m_TexCoord; + vec2 m_Tangent; + vec2 m_Binormal; + float m_Opacity; +}; + +STessShaderResult tessShader ( float inPathWidth ) +{ + vec2 p1 = gl_in[0].gl_Position.xy; + vec2 c1 = gl_in[0].gl_Position.zw; //c1 + vec2 c2 = gl_in[1].gl_Position.xy; //c2 + vec2 p2 = gl_in[1].gl_Position.zw; + vec4 taperData = gl_in[3].gl_Position; + vec2 udata = gl_in[4].gl_Position.xy; + + //Adjust width for taper if necessary. + inPathWidth = taperData.z > 0.0 ? getTaperResult( inPathWidth, beginTaperInfo.x, endTaperInfo.x, taperData.xy, uint(taperData.z) ) : inPathWidth; + + float adjoiningWeight = 0.0; + vec2 adjoining = vec2( 0.0, 0.0 ); + if ( gl_TessCoord.x == floor(gl_TessCoord.x) ) // gl_TessCord.x either 0.0 or 1.0 + { + vec2 point, cross1, cross2; + if ( gl_TessCoord.x == 0.0 ) + { + adjoining = gl_in[2].gl_Position.xy; + point = p1; + cross1 = adjoining; + cross2 = c1; + } + else // gl_TessCoord.x == 1.0 + { + adjoining = gl_in[2].gl_Position.zw; + point = p2; + cross1 = c2; + cross2 = adjoining; + } + float cross = roughCrossProd( cross1, point, cross2 ); + vec3 adjoiningFactors = computeAdjoiningFactors( cross, adjoining, point, gl_TessCoord.y ); + adjoining = adjoiningFactors.xy; + adjoiningWeight = adjoiningFactors.z; + } + + float v = gl_TessCoord.x; + // cubic basis function calculated from v. + float bv0 = (1.0 - v) * (1.0 - v) * (1.0 - v); + float bv1 = 3.0 * v * (1.0 - v) * (1.0 - v); + float bv2 = 3.0 * v * v * (1.0 - v); + float bv3 = v * v * v; + + //u ranges from 0 - 1. What we want is to + //have u range from -1,1. + float u = 2.0 * ( gl_TessCoord.y - .5 ); + + vec2 tangent = getTangent( p1, c1, c2, p2, v ); + vec2 normal = vec2( tangent.y, -tangent.x ); + + vec2 offset = normal * inPathWidth * u; + + vec2 pointOnPath = bv0*p1 + bv1*c1 + bv2*c2 + bv3*p2; + + vec2 finalPosXY = offset + pointOnPath; + + STessShaderResult retval; + retval.m_Position = vec3( mix( finalPosXY, adjoining, adjoiningWeight), 0.0 ); + retval.m_Opacity = taperData.z > 0.0 ? getTaperResult( 1.0, beginTaperInfo.y, endTaperInfo.y, taperData.xy, uint(taperData.z) ) : 1.0; + + // cubic interpolation of the texture coords + retval.m_TexCoord.x = mix( udata.x, udata.y, v ); + retval.m_TexCoord.y = gl_TessCoord.y; + retval.m_Tangent = tangent; + retval.m_Binormal = normal; + + return retval; +} +#endif + +#endif + |