protot/shaders/lines/vs_lines.sc

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$input a_position, a_texcoord0, a_texcoord1, a_texcoord2, a_color0
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$output v_color0
/*
* Copyright 2011-2015 Branimir Karadzic. All rights reserved.
* License: http://www.opensource.org/licenses/BSD-2-Clause
*/
#include "../common/common.sh"
uniform vec4 u_line_params;
#define thickness u_line_params.x
#define miter u_line_params.y
#define aspect u_line_params.z
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#define current_pos a_position
#define prev_pos a_texcoord0
#define next_pos a_texcoord1
#define direction a_texcoord2
void main()
{
vec2 aspect_vec = vec2(aspect, 1.0);
vec4 current_proj = mul(u_modelViewProj, vec4(current_pos, 1.0));
vec4 prev_proj = mul(u_modelViewProj, vec4(prev_pos, 1.0));
vec4 next_proj = mul(u_modelViewProj, vec4(next_pos, 1.0));
vec2 current_screen = current_proj.xy / current_proj.w * aspect_vec;
vec2 prev_screen = prev_proj.xy / prev_proj.w * aspect_vec;
vec2 next_screen = next_proj.xy / next_proj.w * aspect_vec;
float len = thickness;
float orientation = direction;
vec2 dir = vec2(0.0);
if (current_screen == prev_screen) {
dir = normalize(next_screen - current_screen);
} else if (current_screen == next_screen) {
dir = normalize (current_screen - prev_screen);
} else {
vec2 dirA = normalize (current_screen - prev_screen);
if (miter == 1) {
vec2 dirB = normalize(next_screen - current_screen);
//now compute the miter join normal and length
vec2 tangent = normalize(dirA + dirB);
vec2 perp = vec2(-dirA.y, dirA.x);
vec2 miter_vec = vec2(-tangent.y, tangent.x);
dir = tangent;
len = min (2.5 * thickness, thickness / dot(miter_vec, perp));
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} else {
dir = dirA;
}
}
vec2 normal = vec2(-dir.y, dir.x);
normal *= len/2.0;
normal.x /= aspect;
vec4 offset = vec4(normal * orientation, 0.0, 0.0);
gl_Position = current_proj + offset;
v_color0 = a_color0;
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}