51 lines
1.5 KiB
GLSL
51 lines
1.5 KiB
GLSL
#version 150
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// see as reference: https://github.com/mhalber/Lines/blob/master/geometry_shader_lines.h
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// https://stackoverflow.com/questions/52928678/dashed-line-in-opengl3
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layout(lines) in;
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layout(triangle_strip, max_vertices = 4) out;
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const float aa_radius = 0.5;
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uniform vec2 viewport_size;
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uniform float width;
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in float coord_s[];
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out float line_width;
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// x = v tex coord, y = s coord
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out vec2 seg_params;
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void main()
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{
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vec2 ndc_0 = gl_in[0].gl_Position.xy / gl_in[0].gl_Position.w;
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vec2 ndc_1 = gl_in[1].gl_Position.xy / gl_in[1].gl_Position.w;
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vec2 dir = normalize((ndc_1 - ndc_0) * viewport_size);
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vec2 normal_dir = vec2(-dir.y, dir.x);
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line_width = max(1.0, width) + 2.0 * aa_radius;
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float half_line_width = 0.5 * line_width;
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vec2 normal = vec2(line_width / viewport_size[0], line_width / viewport_size[1]) * normal_dir;
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seg_params = vec2(-half_line_width, coord_s[0]);
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gl_Position = vec4((ndc_0 + normal) * gl_in[0].gl_Position.w, gl_in[0].gl_Position.zw);
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EmitVertex();
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seg_params = vec2(-half_line_width, coord_s[0]);
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gl_Position = vec4((ndc_0 - normal) * gl_in[0].gl_Position.w, gl_in[0].gl_Position.zw);
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EmitVertex();
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seg_params = vec2(half_line_width, coord_s[1]);
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gl_Position = vec4((ndc_1 + normal) * gl_in[1].gl_Position.w, gl_in[1].gl_Position.zw);
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EmitVertex();
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seg_params = vec2(half_line_width, coord_s[1]);
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gl_Position = vec4((ndc_1 - normal) * gl_in[1].gl_Position.w, gl_in[1].gl_Position.zw);
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EmitVertex();
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EndPrimitive();
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}
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