shaders/trail.h

   1 #ifndef SHADER_trail_H
   2 #define SHADER_trail_H
   3 static void shader_trail_link(void);
   4 static void shader_trail_register(void);
   5 static struct vg_shader _shader_trail = {
   6    .name = "trail",
   7    .link = shader_trail_link,
   8    .vs =
   9 {
  10 .orig_file = "shaders/trail.vs",
  11 .static_src =
  12 "layout (location=0) in vec4 a_co;\n"
  13 "\n"
  14 "#line       1        1 \n"
  15 "const float k_motion_lerp_amount = 0.01;\n"
  16 "\n"
  17 "#line      2        0 \n"
  18 "\n"
  19 "out vec3 aMotionVec0;\n"
  20 "out vec3 aMotionVec1;\n"
  21 "\n"
  22 "void vs_motion_out( vec4 vproj0, vec4 vproj1 )\n"
  23 "{\n"
  24 "   // This magically solves some artifacting errors!\n"
  25 "   //\n"
  26 "   vproj1 = vproj0*(1.0-k_motion_lerp_amount) + vproj1*k_motion_lerp_amount;\n"
  27 "\n"
  28 "   aMotionVec0 = vec3( vproj0.xy, vproj0.w );\n"
  29 "   aMotionVec1 = vec3( vproj1.xy, vproj1.w );\n"
  30 "}\n"
  31 "\n"
  32 "#line      4        0 \n"
  33 "\n"
  34 "uniform mat4 uPv;\n"
  35 "uniform mat4 uPvPrev;\n"
  36 "\n"
  37 "out float aAlpha;\n"
  38 "\n"
  39 "void main(){\n"
  40 "   vec4 vproj0     = uPv     * vec4( a_co.xyz, 1.0 );\n"
  41 "   vec4 vproj1     = uPvPrev * vec4( a_co.xyz, 1.0 );\n"
  42 "   vs_motion_out( vproj0, vproj1 );\n"
  43 "\n"
  44 "   gl_Position = vproj0;\n"
  45 "   aAlpha = a_co.w;\n"
  46 "}\n"
  47 ""},
  48    .fs =
  49 {
  50 .orig_file = "shaders/trail.fs",
  51 .static_src =
  52 "layout (location = 0) out vec4 oColour;\n"
  53 "in float aAlpha;\n"
  54 "uniform vec4 uColour;\n"
  55 "\n"
  56 "#line       1        1 \n"
  57 "const float k_motion_lerp_amount = 0.01;\n"
  58 "\n"
  59 "#line      2        0 \n"
  60 "\n"
  61 "layout (location = 1) out vec2 oMotionVec;\n"
  62 "\n"
  63 "in vec3 aMotionVec0;\n"
  64 "in vec3 aMotionVec1;\n"
  65 "\n"
  66 "void compute_motion_vectors()\n"
  67 "{\n"
  68 "   // Write motion vectors\n"
  69 "   vec2 vmotion0 = aMotionVec0.xy / aMotionVec0.z;\n"
  70 "   vec2 vmotion1 = aMotionVec1.xy / aMotionVec1.z;\n"
  71 "\n"
  72 "   oMotionVec = (vmotion1-vmotion0) * (1.0/k_motion_lerp_amount);\n"
  73 "}\n"
  74 "\n"
  75 "#line      6        0 \n"
  76 "\n"
  77 "void main(){\n"
  78 "   compute_motion_vectors();\n"
  79 "\n"
  80 "   vec2 ssuv = gl_FragCoord.xy;\n"
  81 "   vec3 vDither = vec3( dot( vec2( 171.0, 231.0 ), ssuv) );\n"
  82 "   float dither = fract( vDither.g / 71.0 ) - 0.5;\n"
  83 "\n"
  84 "   if( aAlpha+dither<0.5 )\n"
  85 "      discard;\n"
  86 "\n"
  87 "   oColour = vec4( uColour.rgb, uColour.a * aAlpha );\n"
  88 "}\n"
  89 ""},
  90 };
  91
  92 static GLuint _uniform_trail_uPv;
  93 static GLuint _uniform_trail_uPvPrev;
  94 static GLuint _uniform_trail_uColour;
  95 static void shader_trail_uPv(m4x4f m){
  96    glUniformMatrix4fv(_uniform_trail_uPv,1,GL_FALSE,(float*)m);
  97 }
  98 static void shader_trail_uPvPrev(m4x4f m){
  99    glUniformMatrix4fv(_uniform_trail_uPvPrev,1,GL_FALSE,(float*)m);
 100 }
 101 static void shader_trail_uColour(v4f v){
 102    glUniform4fv(_uniform_trail_uColour,1,v);
 103 }
 104 static void shader_trail_register(void){
 105    vg_shader_register( &_shader_trail );
 106 }
 107 static void shader_trail_use(void){ glUseProgram(_shader_trail.id); }
 108 static void shader_trail_link(void){
 109    _uniform_trail_uPv = glGetUniformLocation( _shader_trail.id, "uPv" );
 110    _uniform_trail_uPvPrev = glGetUniformLocation( _shader_trail.id, "uPvPrev" );
 111    _uniform_trail_uColour = glGetUniformLocation( _shader_trail.id, "uColour" );
 112 }
 113 #endif /* SHADER_trail_H */