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 vec3 a_co;"
   7         "layout (location=1) in vec4 a_colour;"
   8         "uniform mat4 uPv;"
   9         ""
  10         "out vec4 s_colour;"
  11         ""
  12         "void main()"
  13         "{"
  14         "       vec4 vert_pos = uPv * vec4( a_co, 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                 vec3 co;
  37                 u32 colour;
  38         }
  39         *buffer;
  40
  41         GLuint vao, vbo;
  42         u32 draw_idx, cap, buffer_size;
  43
  44 }
  45 vg_lines;
  46
  47 static void vg_lines_init(void)
  48 {
  49         SHADER_INIT( vg_line_shader );
  50
  51         glGenVertexArrays( 1, &vg_lines.vao );
  52         glGenBuffers( 1, &vg_lines.vbo );
  53         glBindVertexArray( vg_lines.vao );
  54
  55         glBindBuffer( GL_ARRAY_BUFFER, vg_lines.vbo );
  56
  57         vg_lines.cap = 10000;
  58         vg_lines.buffer_size = vg_lines.cap * sizeof( struct vg_lines_vert );
  59
  60         glBufferData( GL_ARRAY_BUFFER, vg_lines.buffer_size, NULL, GL_DYNAMIC_DRAW );
  61         glBindVertexArray( vg_lines.vao );
  62
  63         glVertexAttribPointer(
  64                 0,
  65                 sizeof( vg_lines.buffer[0].co ) / sizeof(float),
  66                 GL_FLOAT,
  67                 GL_FALSE,
  68                 sizeof( struct vg_lines_vert ),
  69                 (void *)0
  70         );
  71         glEnableVertexAttribArray( 0 );
  72
  73         glVertexAttribPointer(
  74                 1,
  75                 4,
  76                 GL_UNSIGNED_BYTE,
  77                 GL_TRUE,
  78                 sizeof( struct vg_lines_vert ),
  79                 (void*)(offsetof( struct vg_lines_vert, colour ))
  80         );
  81         glEnableVertexAttribArray( 1 );
  82         vg_lines.buffer = malloc( vg_lines.buffer_size );
  83 }
  84
  85 static void vg_lines_free(void)
  86 {
  87         glDeleteVertexArrays( 1, &vg_lines.vao );
  88         glDeleteBuffers( 1, &vg_lines.vbo );
  89
  90         free( vg_lines.buffer );
  91 }
  92
  93 static void vg_lines_drawall(void)
  94 {
  95         SHADER_USE( vg_line_shader );
  96         glUniformMatrix4fv( SHADER_UNIFORM( vg_line_shader, "uPv" ), 1, GL_FALSE, (float *)vg_pv );
  97
  98         glBindVertexArray( vg_lines.vao );
  99         glBindBuffer( GL_ARRAY_BUFFER, vg_lines.vbo );
 100
 101         glBufferSubData( GL_ARRAY_BUFFER, 0, vg_lines.draw_idx * sizeof(struct vg_lines_vert), vg_lines.buffer );
 102         glEnable( GL_BLEND );
 103         glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
 104         glBlendEquation( GL_FUNC_ADD );
 105
 106         glDrawArrays( GL_LINES, 0, vg_lines.draw_idx );
 107
 108         glDisable( GL_BLEND );
 109         vg_lines.draw_idx = 0;
 110 }
 111
 112 static void vg_line2( vec3 from, vec3 to, u32 fc, u32 tc )
 113 {
 114         struct vg_lines_vert *v = vg_lines.buffer + vg_lines.draw_idx;
 115         glm_vec3_copy( from, v[0].co );
 116         glm_vec3_copy( to, v[1].co );
 117         v[0].colour = fc;
 118         v[1].colour = tc;
 119
 120         vg_lines.draw_idx += 2;
 121 }
 122
 123 static void vg_line( vec3 from, vec3 to, u32 colour )
 124 {
 125         vg_line2( from, to, colour, colour );
 126 }