239 lines
7.7 KiB
GLSL
239 lines
7.7 KiB
GLSL
/* SPDX-FileCopyrightText: 2018-2022 Blender Authors
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*
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* SPDX-License-Identifier: GPL-2.0-or-later */
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#define GP_XRAY_FRONT 0
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#define GP_XRAY_3DSPACE 1
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#define GP_XRAY_BACK 2
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#define GPENCIL_FLATCAP 1
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/* project 3d point to 2d on screen space */
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vec2 toScreenSpace(vec4 vertex)
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{
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return vec2(vertex.xy / vertex.w) * gpencil_stroke_data.viewport;
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}
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/* Get Z-depth value. */
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float getZdepth(vec4 point)
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{
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if (gpencil_stroke_data.xraymode == GP_XRAY_FRONT) {
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return 0.0;
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}
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if (gpencil_stroke_data.xraymode == GP_XRAY_3DSPACE) {
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return (point.z / point.w);
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}
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if (gpencil_stroke_data.xraymode == GP_XRAY_BACK) {
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return 1.0;
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}
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/* in front by default */
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return 0.0;
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}
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/* check equality but with a small tolerance */
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bool is_equal(vec4 p1, vec4 p2)
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{
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float limit = 0.0001;
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float x = abs(p1.x - p2.x);
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float y = abs(p1.y - p2.y);
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float z = abs(p1.z - p2.z);
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if ((x < limit) && (y < limit) && (z < limit)) {
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return true;
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}
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return false;
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}
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void main(void)
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{
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float MiterLimit = 0.75;
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/* receive 4 points */
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vec4 P0 = gl_in[0].gl_Position;
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vec4 P1 = gl_in[1].gl_Position;
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vec4 P2 = gl_in[2].gl_Position;
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vec4 P3 = gl_in[3].gl_Position;
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/* get the four vertices passed to the shader */
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vec2 sp0 = toScreenSpace(P0); /* start of previous segment */
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vec2 sp1 = toScreenSpace(P1); /* end of previous segment, start of current segment */
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vec2 sp2 = toScreenSpace(P2); /* end of current segment, start of next segment */
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vec2 sp3 = toScreenSpace(P3); /* end of next segment */
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/* culling outside viewport */
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vec2 area = gpencil_stroke_data.viewport * 4.0;
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if (sp1.x < -area.x || sp1.x > area.x) {
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return;
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}
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if (sp1.y < -area.y || sp1.y > area.y) {
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return;
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}
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if (sp2.x < -area.x || sp2.x > area.x) {
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return;
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}
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if (sp2.y < -area.y || sp2.y > area.y) {
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return;
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}
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/* determine the direction of each of the 3 segments (previous, current, next) */
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vec2 v0 = normalize(sp1 - sp0);
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vec2 v1 = normalize(sp2 - sp1);
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vec2 v2 = normalize(sp3 - sp2);
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/* determine the normal of each of the 3 segments (previous, current, next) */
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vec2 n0 = vec2(-v0.y, v0.x);
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vec2 n1 = vec2(-v1.y, v1.x);
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vec2 n2 = vec2(-v2.y, v2.x);
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/* determine miter lines by averaging the normals of the 2 segments */
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vec2 miter_a = normalize(n0 + n1); /* miter at start of current segment */
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vec2 miter_b = normalize(n1 + n2); /* miter at end of current segment */
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/* determine the length of the miter by projecting it onto normal and then inverse it */
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float an1 = dot(miter_a, n1);
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float bn1 = dot(miter_b, n2);
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if (an1 == 0) {
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an1 = 1;
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}
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if (bn1 == 0) {
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bn1 = 1;
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}
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float length_a = geometry_in[1].finalThickness / an1;
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float length_b = geometry_in[2].finalThickness / bn1;
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if (length_a <= 0.0) {
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length_a = 0.01;
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}
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if (length_b <= 0.0) {
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length_b = 0.01;
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}
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/* prevent excessively long miters at sharp corners */
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if (dot(v0, v1) < -MiterLimit) {
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miter_a = n1;
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length_a = geometry_in[1].finalThickness;
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/* close the gap */
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if (dot(v0, n1) > 0) {
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geometry_out.mTexCoord = vec2(0, 0);
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geometry_out.mColor = geometry_in[1].finalColor;
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gl_Position = vec4((sp1 + geometry_in[1].finalThickness * n0) / gpencil_stroke_data.viewport,
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getZdepth(P1),
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1.0);
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gpu_EmitVertex();
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geometry_out.mTexCoord = vec2(0, 0);
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geometry_out.mColor = geometry_in[1].finalColor;
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gl_Position = vec4((sp1 + geometry_in[1].finalThickness * n1) / gpencil_stroke_data.viewport,
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getZdepth(P1),
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1.0);
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gpu_EmitVertex();
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geometry_out.mTexCoord = vec2(0, 0.5);
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geometry_out.mColor = geometry_in[1].finalColor;
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gl_Position = vec4(sp1 / gpencil_stroke_data.viewport, getZdepth(P1), 1.0);
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gpu_EmitVertex();
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EndPrimitive();
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}
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else {
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geometry_out.mTexCoord = vec2(0, 1);
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geometry_out.mColor = geometry_in[1].finalColor;
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gl_Position = vec4((sp1 - geometry_in[1].finalThickness * n1) / gpencil_stroke_data.viewport,
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getZdepth(P1),
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1.0);
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gpu_EmitVertex();
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geometry_out.mTexCoord = vec2(0, 1);
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geometry_out.mColor = geometry_in[1].finalColor;
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gl_Position = vec4((sp1 - geometry_in[1].finalThickness * n0) / gpencil_stroke_data.viewport,
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getZdepth(P1),
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1.0);
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gpu_EmitVertex();
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geometry_out.mTexCoord = vec2(0, 0.5);
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geometry_out.mColor = geometry_in[1].finalColor;
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gl_Position = vec4(sp1 / gpencil_stroke_data.viewport, getZdepth(P1), 1.0);
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gpu_EmitVertex();
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EndPrimitive();
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}
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}
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if (dot(v1, v2) < -MiterLimit) {
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miter_b = n1;
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length_b = geometry_in[2].finalThickness;
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}
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/* Generate the start end-cap (alpha < 0 used as end-cap flag). */
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float extend = gpencil_stroke_data.fill_stroke ? 2 : 1;
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if ((gpencil_stroke_data.caps_start != GPENCIL_FLATCAP) && is_equal(P0, P2)) {
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geometry_out.mTexCoord = vec2(1, 0.5);
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geometry_out.mColor = vec4(geometry_in[1].finalColor.rgb, geometry_in[1].finalColor.a * -1.0);
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vec2 svn1 = normalize(sp1 - sp2) * length_a * 4.0 * extend;
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gl_Position = vec4((sp1 + svn1) / gpencil_stroke_data.viewport, getZdepth(P1), 1.0);
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gpu_EmitVertex();
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geometry_out.mTexCoord = vec2(0, 0);
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geometry_out.mColor = vec4(geometry_in[1].finalColor.rgb, geometry_in[1].finalColor.a * -1.0);
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gl_Position = vec4(
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(sp1 - (length_a * 2.0) * miter_a) / gpencil_stroke_data.viewport, getZdepth(P1), 1.0);
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gpu_EmitVertex();
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geometry_out.mTexCoord = vec2(0, 1);
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geometry_out.mColor = vec4(geometry_in[1].finalColor.rgb, geometry_in[1].finalColor.a * -1.0);
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gl_Position = vec4(
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(sp1 + (length_a * 2.0) * miter_a) / gpencil_stroke_data.viewport, getZdepth(P1), 1.0);
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gpu_EmitVertex();
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}
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/* generate the triangle strip */
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geometry_out.mTexCoord = vec2(0, 0);
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geometry_out.mColor = geometry_in[1].finalColor;
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gl_Position = vec4(
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(sp1 + length_a * miter_a) / gpencil_stroke_data.viewport, getZdepth(P1), 1.0);
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gpu_EmitVertex();
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geometry_out.mTexCoord = vec2(0, 1);
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geometry_out.mColor = geometry_in[1].finalColor;
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gl_Position = vec4(
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(sp1 - length_a * miter_a) / gpencil_stroke_data.viewport, getZdepth(P1), 1.0);
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gpu_EmitVertex();
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geometry_out.mTexCoord = vec2(0, 0);
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geometry_out.mColor = geometry_in[2].finalColor;
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gl_Position = vec4(
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(sp2 + length_b * miter_b) / gpencil_stroke_data.viewport, getZdepth(P2), 1.0);
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gpu_EmitVertex();
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geometry_out.mTexCoord = vec2(0, 1);
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geometry_out.mColor = geometry_in[2].finalColor;
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gl_Position = vec4(
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(sp2 - length_b * miter_b) / gpencil_stroke_data.viewport, getZdepth(P2), 1.0);
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gpu_EmitVertex();
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/* Generate the end end-cap (alpha < 0 used as end-cap flag). */
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if ((gpencil_stroke_data.caps_end != GPENCIL_FLATCAP) && is_equal(P1, P3)) {
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geometry_out.mTexCoord = vec2(0, 1);
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geometry_out.mColor = vec4(geometry_in[2].finalColor.rgb, geometry_in[2].finalColor.a * -1.0);
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gl_Position = vec4(
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(sp2 + (length_b * 2.0) * miter_b) / gpencil_stroke_data.viewport, getZdepth(P2), 1.0);
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gpu_EmitVertex();
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geometry_out.mTexCoord = vec2(0, 0);
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geometry_out.mColor = vec4(geometry_in[2].finalColor.rgb, geometry_in[2].finalColor.a * -1.0);
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gl_Position = vec4(
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(sp2 - (length_b * 2.0) * miter_b) / gpencil_stroke_data.viewport, getZdepth(P2), 1.0);
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gpu_EmitVertex();
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geometry_out.mTexCoord = vec2(1, 0.5);
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geometry_out.mColor = vec4(geometry_in[2].finalColor.rgb, geometry_in[2].finalColor.a * -1.0);
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vec2 svn2 = normalize(sp2 - sp1) * length_b * 4.0 * extend;
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gl_Position = vec4((sp2 + svn2) / gpencil_stroke_data.viewport, getZdepth(P2), 1.0);
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gpu_EmitVertex();
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}
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EndPrimitive();
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}
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