vg/vg_lines.h

   1 // Copyright (C) 2021 Harry Godden (hgn) - All Rights Reserved
   2
   3 SHADER_DEFINE( vg_line_shader,
   4
   5         // VERTEX
   6         "layout (location=0) in vec2 a_co;"
   7         "layout (location=1) in vec4 a_colour;"
   8         "uniform mat3 uPv;"
   9         ""
  10         "out vec4 s_colour;"
  11         ""
  12         "void main()"
  13         "{"
  14         "       vec4 vert_pos = vec4( uPv * vec3( a_co, 1.0 ), 1.0 );"
  15         "  s_colour = a_colour;"
  16         "       gl_Position = vert_pos;"
  17         "}",
  18
  19         // FRAGMENT
  20         "out vec4 FragColor;"
  21         ""
  22         "in vec4 s_colour;"
  23         ""
  24         "void main()"
  25         "{"
  26         "       FragColor = s_colour;"
  27         "}"
  28         ,
  29         UNIFORMS({ "uPv" })
  30 )
  31
  32 struct
  33 {
  34         struct vg_lines_vert
  35         {
  36                 v2f co;
  37                 u32 colour;
  38         }
  39         *buffer;
  40
  41         GLuint vao, vbo;
  42         u32 draw_idx, cap, buffer_size;
  43 }
  44 vg_lines;
  45
  46 static void vg_lines_init(void)
  47 {
  48         SHADER_INIT( vg_line_shader );
  49
  50         glGenVertexArrays( 1, &vg_lines.vao );
  51         glGenBuffers( 1, &vg_lines.vbo );
  52         glBindVertexArray( vg_lines.vao );
  53
  54         glBindBuffer( GL_ARRAY_BUFFER, vg_lines.vbo );
  55
  56         vg_lines.cap = 10000;
  57         vg_lines.buffer_size = vg_lines.cap * sizeof( struct vg_lines_vert );
  58
  59         glBufferData( GL_ARRAY_BUFFER, vg_lines.buffer_size, NULL, GL_DYNAMIC_DRAW );
  60         glBindVertexArray( vg_lines.vao );
  61
  62         glVertexAttribPointer(
  63                 0,
  64                 sizeof( vg_lines.buffer[0].co ) / sizeof(float),
  65                 GL_FLOAT,
  66                 GL_FALSE,
  67                 sizeof( struct vg_lines_vert ),
  68                 (void *)0
  69         );
  70         glEnableVertexAttribArray( 0 );
  71
  72         glVertexAttribPointer(
  73                 1,
  74                 4,
  75                 GL_UNSIGNED_BYTE,
  76                 GL_TRUE,
  77                 sizeof( struct vg_lines_vert ),
  78                 (void*)(offsetof( struct vg_lines_vert, colour ))
  79         );
  80         glEnableVertexAttribArray( 1 );
  81         vg_lines.buffer = malloc( vg_lines.buffer_size );
  82 }
  83
  84 static void vg_lines_free(void)
  85 {
  86         glDeleteVertexArrays( 1, &vg_lines.vao );
  87         glDeleteBuffers( 1, &vg_lines.vbo );
  88
  89         free( vg_lines.buffer );
  90 }
  91
  92 static void vg_lines_drawall(float* projection)
  93 {
  94         SHADER_USE( vg_line_shader );
  95         glUniformMatrix3fv( SHADER_UNIFORM( vg_line_shader, "uPv" ), 1, GL_FALSE, projection );
  96
  97         glBindVertexArray( vg_lines.vao );
  98         glBindBuffer( GL_ARRAY_BUFFER, vg_lines.vbo );
  99
 100         glBufferSubData( GL_ARRAY_BUFFER, 0, vg_lines.draw_idx * sizeof(struct vg_lines_vert), vg_lines.buffer );
 101         glEnable( GL_BLEND );
 102         glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
 103         glBlendEquation( GL_FUNC_ADD );
 104
 105         glDrawArrays( GL_LINES, 0, vg_lines.draw_idx );
 106
 107         glDisable( GL_BLEND );
 108         vg_lines.draw_idx = 0;
 109 }
 110
 111 static void vg_line2( v2f from, v2f to, u32 fc, u32 tc )
 112 {
 113         struct vg_lines_vert *v = vg_lines.buffer + vg_lines.draw_idx;
 114         v2_copy( from, v[0].co );
 115         v2_copy( to, v[1].co );
 116         v[0].colour = fc;
 117         v[1].colour = tc;
 118
 119         vg_lines.draw_idx += 2;
 120 }
 121
 122 static void vg_line( v2f from, v2f to, u32 colour )
 123 {
 124         vg_line2( from, to, colour, colour );
 125 }
 126
 127 static void vg_line_box( v2f min, v2f max, u32 colour )
 128 {
 129         vg_line( min, (v2f){min[0],max[1]}, colour );
 130         vg_line( (v2f){min[0],max[1]}, max, colour );
 131         vg_line( max, (v2f){max[0],min[1]}, colour );
 132         vg_line( (v2f){max[0],min[1]}, min, colour );
 133 }