56 lines
1.7 KiB
GLSL
56 lines
1.7 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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layout(lines) in;
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layout(triangle_strip, max_vertices = 4) out;
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const vec2 aa_radius = vec2(0.5);
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uniform vec2 viewport_size;
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uniform float width;
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out float line_width;
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out float line_length;
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out vec2 uv;
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void main()
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{
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float u_width = viewport_size[0];
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float u_height = viewport_size[1];
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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 viewport_line_vector = 0.5 * (ndc_1 - ndc_0) * viewport_size;
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vec2 dir = normalize(viewport_line_vector);
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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[0];
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line_length = length(viewport_line_vector) + 2.0 * aa_radius[1];
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vec2 normal = vec2(line_width / u_width, line_width / u_height) * normal_dir;
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vec2 extension = vec2(aa_radius[1] / u_width, aa_radius[1] / u_height) * dir;
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float half_line_width = 0.5 * line_width;
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float half_line_length = 0.5 * line_length;
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uv = vec2(-half_line_width, half_line_length);
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gl_Position = vec4((ndc_0 + normal - extension) * gl_in[0].gl_Position.w, gl_in[0].gl_Position.zw);
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EmitVertex();
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uv = vec2(-half_line_width, -half_line_length);
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gl_Position = vec4((ndc_0 - normal - extension) * gl_in[0].gl_Position.w, gl_in[0].gl_Position.zw);
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EmitVertex();
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uv = vec2(half_line_width, half_line_length);
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gl_Position = vec4((ndc_1 + normal + extension) * gl_in[1].gl_Position.w, gl_in[1].gl_Position.zw);
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EmitVertex();
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uv = vec2(half_line_width, -half_line_length);
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gl_Position = vec4((ndc_1 - normal + extension) * 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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