Mike Erwin
83d5a919e2
"varying" is redundant here, all GS inputs & outputs vary. Any code that uses this will be GLSL 1.3 or newer.
101 lines
3.1 KiB
GLSL
101 lines
3.1 KiB
GLSL
/*
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* Used the implementation of wide lines of Timo Suoranta (http://neure.dy.fi/wideline.html)
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*/
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#define PASSTHROUGH 0
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layout(lines) in;
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#if defined(DRAW_LINE)
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#if PASSTHROUGH
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layout(line_strip, max_vertices = 10) out;
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#else
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layout(triangle_strip, max_vertices = 6) out;
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#endif
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out float t;
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in vec4 varying_vertex_color_line[];
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out vec4 varying_vertex_color;
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uniform ivec4 viewport;
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uniform float line_width;
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uniform int stipple_factor;
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void main(void)
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{
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vec2 window_size = viewport.zw;
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vec4 start = gl_in[0].gl_Position;
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vec4 end = gl_in[1].gl_Position;
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#if PASSTHROUGH
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gl_Position = start; EmitVertex();
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gl_Position = end; EmitVertex();
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EndPrimitive();
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return;
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#endif
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/* t = 0 t = ~(len(end - start) + 2*line_width)
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* A-------------------------------------B
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* | | | |
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* | side | |
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* | | | |
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* |--axis--*start--------------*end-----|
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* | | | |
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* | | | |
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* | | | |
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* D-------------------------------------C
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*/
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/* Clip the line before homogenization.
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* Compute line start and end distances to nearplane in clipspace
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* Distances are t0 = dot(start, plane) and t1 = dot(end, plane)
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*/
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float t0 = start.z + start.w;
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float t1 = end.z + end.w;
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if (t0 < 0.0) {
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if (t1 < 0.0) {
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return;
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}
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start = mix(start, end, (0 - t0) / (t1 - t0));
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}
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if (t1 < 0.0) {
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end = mix(start, end, (0 - t0) / (t1 - t0));
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}
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/* Compute line axis and side vector in screen space */
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vec2 startInNDC = start.xy / start.w; /* clip to NDC: homogenize and drop z */
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vec2 endInNDC = end.xy / end.w;
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vec2 lineInNDC = endInNDC - startInNDC;
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vec2 lineInScreen = lineInNDC * window_size; /* ndc to screen (direction vector) */
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vec2 axisInScreen = normalize(lineInScreen);
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vec2 sideInScreen = vec2(-axisInScreen.y, axisInScreen.x); /* rotate */
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vec2 axisInNDC = axisInScreen / window_size; /* screen to NDC */
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vec2 sideInNDC = sideInScreen / window_size;
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vec4 axis = vec4(axisInNDC, 0.0, 0.0) * line_width; /* NDC to clip (delta vector) */
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vec4 side = vec4(sideInNDC, 0.0, 0.0) * line_width;
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vec4 A = (start + (side - axis) * start.w);
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vec4 B = (end + (side + axis) * end.w);
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vec4 C = (end - (side - axis) * end.w);
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vec4 D = (start - (side + axis) * start.w);
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/* There is no relation between lines yet */
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/* TODO Pass here t0 to make continuous pattern. */
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t0 = 0;
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t1 = (length(lineInScreen) + 2 * line_width) / (2 * line_width * stipple_factor);
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gl_Position = A; t = t0; varying_vertex_color = varying_vertex_color_line[0]; EmitVertex();
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gl_Position = D; t = t0; varying_vertex_color = varying_vertex_color_line[0]; EmitVertex();
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gl_Position = B; t = t1; varying_vertex_color = varying_vertex_color_line[1]; EmitVertex();
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gl_Position = C; t = t1; varying_vertex_color = varying_vertex_color_line[1]; EmitVertex();
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EndPrimitive();
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}
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#else
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void main(void)
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{
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}
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#endif
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