+#ifndef SHADER_trail_H
+#define SHADER_trail_H
+static void shader_trail_link(void);
+static void shader_trail_register(void);
+static struct vg_shader _shader_trail = {
+ .name = "trail",
+ .link = shader_trail_link,
+ .vs =
+{
+.orig_file = "shaders/trail.vs",
+.static_src =
+"layout (location=0) in vec4 a_co;\n"
+"\n"
+"#line 1 1 \n"
+"const float k_motion_lerp_amount = 0.01;\n"
+"\n"
+"#line 2 0 \n"
+"\n"
+"out vec3 aMotionVec0;\n"
+"out vec3 aMotionVec1;\n"
+"\n"
+"void vs_motion_out( vec4 vproj0, vec4 vproj1 )\n"
+"{\n"
+" // This magically solves some artifacting errors!\n"
+" //\n"
+" vproj1 = vproj0*(1.0-k_motion_lerp_amount) + vproj1*k_motion_lerp_amount;\n"
+"\n"
+" aMotionVec0 = vec3( vproj0.xy, vproj0.w );\n"
+" aMotionVec1 = vec3( vproj1.xy, vproj1.w );\n"
+"}\n"
+"\n"
+"#line 4 0 \n"
+"\n"
+"uniform mat4 uPv;\n"
+"uniform mat4 uPvPrev;\n"
+"\n"
+"out float aAlpha;\n"
+"\n"
+"void main(){\n"
+" vec4 vproj0 = uPv * vec4( a_co.xyz, 1.0 );\n"
+" vec4 vproj1 = uPvPrev * vec4( a_co.xyz, 1.0 );\n"
+" vs_motion_out( vproj0, vproj1 );\n"
+"\n"
+" gl_Position = vproj0;\n"
+" aAlpha = a_co.w;\n"
+"}\n"
+""},
+ .fs =
+{
+.orig_file = "shaders/trail.fs",
+.static_src =
+"layout (location = 0) out vec4 oColour;\n"
+"in float aAlpha;\n"
+"uniform vec4 uColour;\n"
+"\n"
+"#line 1 1 \n"
+"const float k_motion_lerp_amount = 0.01;\n"
+"\n"
+"#line 2 0 \n"
+"\n"
+"layout (location = 1) out vec2 oMotionVec;\n"
+"\n"
+"in vec3 aMotionVec0;\n"
+"in vec3 aMotionVec1;\n"
+"\n"
+"void compute_motion_vectors()\n"
+"{\n"
+" // Write motion vectors\n"
+" vec2 vmotion0 = aMotionVec0.xy / aMotionVec0.z;\n"
+" vec2 vmotion1 = aMotionVec1.xy / aMotionVec1.z;\n"
+"\n"
+" oMotionVec = (vmotion1-vmotion0) * (1.0/k_motion_lerp_amount);\n"
+"}\n"
+"\n"
+"#line 6 0 \n"
+"\n"
+"void main(){\n"
+" compute_motion_vectors();\n"
+"\n"
+" vec2 ssuv = gl_FragCoord.xy;\n"
+" vec3 vDither = vec3( dot( vec2( 171.0, 231.0 ), ssuv) );\n"
+" float dither = fract( vDither.g / 71.0 ) - 0.5;\n"
+"\n"
+" if( aAlpha+dither<0.5 )\n"
+" discard;\n"
+"\n"
+" oColour = vec4( uColour.rgb, uColour.a * aAlpha );\n"
+"}\n"
+""},
+};
+
+static GLuint _uniform_trail_uPv;
+static GLuint _uniform_trail_uPvPrev;
+static GLuint _uniform_trail_uColour;
+static void shader_trail_uPv(m4x4f m){
+ glUniformMatrix4fv(_uniform_trail_uPv,1,GL_FALSE,(float*)m);
+}
+static void shader_trail_uPvPrev(m4x4f m){
+ glUniformMatrix4fv(_uniform_trail_uPvPrev,1,GL_FALSE,(float*)m);
+}
+static void shader_trail_uColour(v4f v){
+ glUniform4fv(_uniform_trail_uColour,1,v);
+}
+static void shader_trail_register(void){
+ vg_shader_register( &_shader_trail );
+}
+static void shader_trail_use(void){ glUseProgram(_shader_trail.id); }
+static void shader_trail_link(void){
+ _uniform_trail_uPv = glGetUniformLocation( _shader_trail.id, "uPv" );
+ _uniform_trail_uPvPrev = glGetUniformLocation( _shader_trail.id, "uPvPrev" );
+ _uniform_trail_uColour = glGetUniformLocation( _shader_trail.id, "uColour" );
+}
+#endif /* SHADER_trail_H */