[vg.git] / vg_imgui.h

/* Copyright (C) 2021-2023 Harry Godden (hgn) - All Rights Reserved */

/*
 *  Principles:
 *    
 *    1. layout is defined by subdividing
 *    2. a parent node should never be resized by the content after creation
 *    3. when the ui is in an interactive state, no controls should ever move
 */


#ifndef VG_IMGUI_H
#define VG_IMGUI_H

#define VG_GAME
#include "vg/vg.h"
#include "vg/vg_tex.h"
#include "vg/vg_shader.h"

typedef i16                             ui_px;
typedef ui_px                           ui_rect[4];
typedef struct ui_vert  ui_vert;

enum ui_axis {
   k_ui_axis_h = 0x0u,
   k_ui_axis_v = 0x1u,
};

/* Relative to cursor p0 */
enum ui_align
{  /*                         DC      BA */
   k_ui_align_left          = 0x0000| 0x00,
   k_ui_align_right         = 0x0000| 0x01,
   k_ui_align_center        = 0x0000| 0x02,

   k_ui_align_middle        = 0x0100,
   k_ui_align_middle_left   = 0x0100| 0x00,
   k_ui_align_middle_right  = 0x0100| 0x01,
   k_ui_align_middle_center = 0x0100| 0x02,

   k_ui_align_bottom        = 0x0200,
   k_ui_align_bottom_left   = 0x0200| 0x00,
   k_ui_align_bottom_right  = 0x0200| 0x01,
   k_ui_align_bottom_center = 0x0200| 0x02,
};

#pragma pack(push,1)
struct ui_vert
{
   ui_px co[2];
   u8 uv[2];
   u32 colour;
};
#pragma pack(pop)

enum ui_scheme_colour{
   k_ui_bg      = 0,
   k_ui_fg      = 8,
   k_ui_hue     = 16,
   k_ui_red     = 16,
   k_ui_orange,
   k_ui_yellow,
   k_ui_green,
   k_ui_aqua,
   k_ui_blue,
   k_ui_purple,
   k_ui_gray,
   k_ui_brighter = 8
};

typedef u32 ui_scheme[8*4];

#define UI_RGB( STDHEX )          0xff000000       |\
                         ((STDHEX&0x000000ff)<<16) |\
                         ((STDHEX&0x0000ff00)    ) |\
                         ((STDHEX&0x00ff0000)>>16) 

struct{
   struct ui_vert *vertex_buffer;
   u16            *indice_buffer;
        u32 max_verts, max_indices, 
       cur_vert,  cur_indice,
       vert_start, indice_start;

   void *focused_control_id; /* uses the memory location of various locking
                                controls as an id */
   u32 focused_control_hit;
   enum ui_control_type{
      k_ui_control_none,
      k_ui_control_textbox,
   }
   focused_control_type;
        
        GLuint tex_glyphs, vao, vbo, ebo;

        ui_px mouse[2], mouse_click[2];
   u32 mouse_state[2];
   u32 ignore_input_frames;

   ui_rect click_fader;
   float click_fade_opacity;

   ui_scheme scheme;
} 
static vg_ui = {
   .scheme = {
      [ k_ui_bg+0 ] = UI_RGB( 0x1d2021 ),
      [ k_ui_bg+1 ] = UI_RGB( 0x282828 ),
      [ k_ui_bg+2 ] = UI_RGB( 0x3c3836 ),
      [ k_ui_bg+3 ] = UI_RGB( 0x504945 ),
      [ k_ui_bg+4 ] = UI_RGB( 0x665c54 ),
      [ k_ui_bg+5 ] = UI_RGB( 0x7c6f64 ),
      [ k_ui_bg+6 ] = UI_RGB( 0x928374 ),
      [ k_ui_bg+7 ] = UI_RGB( 0xa89984 ),

      [ k_ui_fg+0 ] = UI_RGB( 0xebdbb2 ),
      [ k_ui_fg+1 ] = UI_RGB( 0xfbf1c7 ),
      [ k_ui_fg+2 ] = UI_RGB( 0xd5c4a1 ),
      [ k_ui_fg+3 ] = UI_RGB( 0xbdae93 ),
      [ k_ui_fg+4 ] = UI_RGB( 0xa89984 ),
      [ k_ui_fg+5 ] = UI_RGB( 0x000000 ),
      [ k_ui_fg+6 ] = UI_RGB( 0x000000 ),
      [ k_ui_fg+7 ] = UI_RGB( 0x000000 ),

      [ k_ui_red    ] = UI_RGB( 0xcc241d ),
      [ k_ui_orange ] = UI_RGB( 0xd65d0e ),
      [ k_ui_yellow ] = UI_RGB( 0xd79921 ),
      [ k_ui_green  ] = UI_RGB( 0x98971a ),
      [ k_ui_aqua   ] = UI_RGB( 0x689d6a ),
      [ k_ui_blue   ] = UI_RGB( 0x458588 ),
      [ k_ui_purple ] = UI_RGB( 0xb16286 ),
      [ k_ui_gray   ] = UI_RGB( 0x928374 ),
      [ k_ui_red    + k_ui_brighter ] = UI_RGB( 0xfb4934 ),
      [ k_ui_orange + k_ui_brighter ] = UI_RGB( 0xfe8019 ),
      [ k_ui_yellow + k_ui_brighter ] = UI_RGB( 0xfabd2f ),
      [ k_ui_green  + k_ui_brighter ] = UI_RGB( 0xb8bb26 ),
      [ k_ui_aqua   + k_ui_brighter ] = UI_RGB( 0x8ec07c ),
      [ k_ui_blue   + k_ui_brighter ] = UI_RGB( 0x83a598 ),
      [ k_ui_purple + k_ui_brighter ] = UI_RGB( 0xd3869b ),
      [ k_ui_gray   + k_ui_brighter ] = UI_RGB( 0xa89984 ),
   }
};

static struct vg_shader _shader_ui =
{
   .name = "[vg] ui",
   .link = NULL,
   .vs = 
   {
      .orig_file = NULL,
      .static_src = 
        "layout (location=0) in vec2 a_co;"
        "layout (location=1) in vec2 a_uv;"
        "layout (location=2) in vec4 a_colour;"
        "uniform mat3 uPv;"
        ""
        "out vec2 aTexCoords;"
        "out vec4 aColour;"
        "out vec2 aWsp;"
        ""
        "void main()"
        "{"
                "gl_Position = vec4( uPv * vec3( a_co, 1.0 ), 1.0 );"
                "aTexCoords = a_uv * 0.0078125;"
                "aColour = a_colour;"
                
                "aWsp = a_co;"
        "}",
   },
   .fs = 
   {
      .orig_file = NULL,
      .static_src = 
        "uniform sampler2D uTexGlyphs;"
        "out vec4 FragColor;"
        ""
        "in vec2 aTexCoords;"
        "in vec4 aColour;"
        ""
        "in vec2 aWsp;"

   "vec2 rand_hash22( vec2 p )"
   "{"
      "vec3 p3 = fract(vec3(p.xyx) * 213.8976123);"
      "p3 += dot(p3, p3.yzx+19.19);"
      "return fract(vec2((p3.x + p3.y)*p3.z, (p3.x+p3.z)*p3.y));"
   "}"
        ""
        "void main()"
        "{"
                "vec4 diffuse = aColour;"
                
                "if( diffuse.a == 0.0 )"
                "{"
                        "diffuse.a = texture( uTexGlyphs, aTexCoords ).r;"
                "}"
                
                "FragColor = diffuse;"
        "}"
   }
};

static struct vg_shader _shader_ui_image =
{
   .name = "[vg] ui_image",
   .link = NULL,
   .vs = 
   {
      .orig_file = NULL,
      .static_src = 
        "layout (location=0) in vec2 a_co;"
        "layout (location=1) in vec2 a_uv;"
        "layout (location=2) in vec4 a_colour;"
        "uniform mat3 uPv;"

        "out vec2 aTexCoords;"
        "out vec4 aColour;"
        "out vec2 aWsp;"

        "void main()"
        "{"
                "gl_Position = vec4( uPv * vec3( a_co, 1.0 ), 1.0 );"
                "aTexCoords = a_uv * 0.0078125;"
                "aColour = a_colour;"
                
                "aWsp = a_co;"
        "}",
   },
   .fs = 
   {
      .orig_file = NULL,
      .static_src = 
        "uniform sampler2D uTexImage;"
        "out vec4 FragColor;"

        "in vec2 aTexCoords;"
        "in vec4 aColour;"
        "in vec2 aWsp;"

        "void main()"
        "{"
                "vec4 colour = texture( uTexImage, aTexCoords );"

      /* wtf is this?? */
#if 0
      "float value = dot(vec4(1.0),colour)*0.25;"

      "vec3 col = vec3(pow(cos(value*3.14159265*2.0)*0.5+0.5,0.5))"
                  "* vec3(step(value,0.5),0.3,step(1.0-value,0.5));"
                "FragColor = vec4( col*4.0, 1.0 );"
#endif

                "FragColor = colour;"
        "}"
   }
};
#define UI_GLYPH_SPACING_X 8

VG_STATIC void _vg_ui_init(void)
{
   if( !vg_shader_compile( &_shader_ui ) ||
       !vg_shader_compile( &_shader_ui_image ) ) 
      vg_fatal_error( "Failed to compile ui shader" );

   /*
    * Vertex buffer
    * ----------------------------------------
    */

   vg_ui.max_indices = 20000;
   vg_ui.max_verts = 30000;
        
        /* Generate the buffer we are gonna be drawing to */
   glGenVertexArrays( 1, &vg_ui.vao );
   glGenBuffers( 1, &vg_ui.vbo );
   glGenBuffers( 1, &vg_ui.ebo );

   glBindVertexArray( vg_ui.vao );
   glBindBuffer( GL_ARRAY_BUFFER, vg_ui.vbo );
   
   glBufferData( GL_ARRAY_BUFFER, 
         vg_ui.max_verts * sizeof( struct ui_vert ), 
         NULL, GL_DYNAMIC_DRAW );
   glBindVertexArray( vg_ui.vao );
   
   glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, vg_ui.ebo );
   glBufferData( GL_ELEMENT_ARRAY_BUFFER, 
         vg_ui.max_indices * sizeof( u16 ), NULL, GL_DYNAMIC_DRAW );

   VG_CHECK_GL_ERR();

   /* Set pointers */
   u32 const stride = sizeof( struct ui_vert );
   
   /* XY */
   glVertexAttribPointer( 0, 2, GL_SHORT, GL_FALSE, stride, 
                          (void *)offsetof( struct ui_vert, co ) );
   glEnableVertexAttribArray( 0 );
   
   /* UV */
   glVertexAttribPointer( 1, 2, GL_UNSIGNED_BYTE, GL_FALSE, stride, 
                          (void *)offsetof( struct ui_vert, uv ) );
   glEnableVertexAttribArray( 1 );
   
   /* COLOUR */
   glVertexAttribPointer( 2, 4, GL_UNSIGNED_BYTE, GL_TRUE, stride, 
                          (void *)offsetof( struct ui_vert, colour ) );
   glEnableVertexAttribArray( 2 );
   
   VG_CHECK_GL_ERR();

        /* Alloc RAM default context */
   u32 vert_size = vg_ui.max_verts*sizeof(struct ui_vert),
       inds_size = vg_align8( vg_ui.max_indices*sizeof(u16) );
   
   vg_ui.vertex_buffer = vg_linear_alloc( vg_mem.rtmemory, vert_size );
   vg_ui.indice_buffer = vg_linear_alloc( vg_mem.rtmemory, inds_size );

   /* font
    * -----------------------------------------------------
    */
   
        /* Load default font */
   u32 compressed[] = {
      #include "vg/vg_pxfont_thin.h"
   };

   u32 pixels = 0, total = 256*256, data = 0;
   u8 image[256*256];
   
   while( pixels < total ){
      for( int b = 31; b >= 0; b-- ){
         image[ pixels ++ ] = (compressed[data] & (0x1u << b))? 0xffu: 0x00u;
         
         if( pixels >= total ){
            total = 0;
            break;
         }
      }
      data++;
   }
   
   glGenTextures( 1, &vg_ui.tex_glyphs );
   glBindTexture( GL_TEXTURE_2D, vg_ui.tex_glyphs );
   glTexImage2D( GL_TEXTURE_2D, 0, GL_R8, 256, 256, 0, 
                 GL_RED, GL_UNSIGNED_BYTE, image );

   VG_CHECK_GL_ERR();
   glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
   glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
   glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
   glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
}

enum ui_shader {
   k_ui_shader_colour,
   k_ui_shader_image
};

static void rect_copy( ui_rect a, ui_rect b )
{
   for( int i=0; i<4; i++ )
      b[i] = a[i];
}

VG_STATIC void ui_flush( enum ui_shader shader )
{
   u32 vertex_offset = vg_ui.vert_start*sizeof(ui_vert),
       vertex_count  = vg_ui.cur_vert-vg_ui.vert_start,
       vertex_size   = vertex_count*sizeof(ui_vert),

       indice_offset = vg_ui.indice_start*sizeof(u16),
       indice_count  = vg_ui.cur_indice-vg_ui.indice_start,
       indice_size   = indice_count * sizeof(u16);

   if( !vertex_size || !indice_size )
      return;
        
        glBindVertexArray( vg_ui.vao );
        glBindBuffer( GL_ARRAY_BUFFER, vg_ui.vbo );
        glBufferSubData( GL_ARRAY_BUFFER, vertex_offset, vertex_size,
                    vg_ui.vertex_buffer+vg_ui.vert_start );
        
        glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, vg_ui.ebo );
        glBufferSubData( GL_ELEMENT_ARRAY_BUFFER, indice_offset, indice_size,
                    vg_ui.indice_buffer+vg_ui.indice_start );
        
        glEnable( GL_BLEND );
        glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
        glBlendEquation( GL_FUNC_ADD );
        
        m3x3f view = M3X3_IDENTITY;
   m3x3_translate( view, (v3f){ -1.0f, 1.0f, 0.0f } );
   m3x3_scale( view, (v3f){ 1.0f/((float)vg.window_x*0.5f), 
                           -1.0f/((float)vg.window_y*0.5f), 1.0f } );
        
   if( shader == k_ui_shader_colour ){
      glUseProgram( _shader_ui.id );
      
      glUniformMatrix3fv( glGetUniformLocation( _shader_ui.id, "uPv" ), 1, 
                          GL_FALSE, (float *)view );
        
      glActiveTexture( GL_TEXTURE0 );
      glBindTexture( GL_TEXTURE_2D, vg_ui.tex_glyphs );
      glUniform1i( glGetUniformLocation( _shader_ui.id, "uTexGlyphs" ), 0 );
   }
   else if( shader == k_ui_shader_image ){
      glUseProgram( _shader_ui_image.id );
      glUniformMatrix3fv( glGetUniformLocation( _shader_ui_image.id, "uPv" ), 1, 
                          GL_FALSE, (float *)view );
      glUniform1i( glGetUniformLocation(_shader_ui_image.id,"uTexImage"), 0 );
   }
   else
      vg_fatal_error( "Invalid UI shader (%d)\n", shader );
        
        glDrawElements( GL_TRIANGLES, indice_count, GL_UNSIGNED_SHORT, 
                   (void *)(vg_ui.indice_start*sizeof(u16)) );

        glDisable( GL_BLEND );

   vg_ui.indice_start = vg_ui.cur_indice;
   vg_ui.vert_start = vg_ui.cur_vert;
}

static void ui_fill_rect( ui_rect rect, u32 colour, ui_px uv[4] )
{
   /* this if far from ideal but stops us from crashing */
   if( (vg_ui.cur_vert + 4 > vg_ui.max_verts) || 
       (vg_ui.cur_indice + 6 > vg_ui.max_indices))
      return;

   struct ui_vert *vertices = &vg_ui.vertex_buffer[ vg_ui.cur_vert ];
        u16            *indices  = &vg_ui.indice_buffer[ vg_ui.cur_indice ];

   for( int i=0; i<4; i++ ){
      vertices[i].colour = colour;
   }

        vertices[0].co[0] = rect[0];
        vertices[0].co[1] = rect[1];
        vertices[0].uv[0] = uv[0];
        vertices[0].uv[1] = uv[1];
        vertices[1].co[0] = rect[0]+rect[2];
        vertices[1].co[1] = rect[1];
        vertices[1].uv[0] = uv[2];
        vertices[1].uv[1] = uv[1];
        vertices[2].co[0] = rect[0]+rect[2];
        vertices[2].co[1] = rect[1]+rect[3];
        vertices[2].uv[0] = uv[2];
        vertices[2].uv[1] = uv[3];
        vertices[3].co[0] = rect[0];
        vertices[3].co[1] = rect[1]+rect[3];
        vertices[3].uv[0] = uv[0];
        vertices[3].uv[1] = uv[3];
        u16 ind_start = vg_ui.cur_vert;
        
        u16 start = vg_ui.cur_vert;
   u32 mesh[] = { 0,2,1, 0,3,2 };

   for( u32 i=0; i<vg_list_size(mesh); i++ ){
      indices[i] = start+mesh[i];
   }

        vg_ui.cur_indice += 6;
        vg_ui.cur_vert += 4;
}

static void ui_fill( ui_rect rect, u32 colour )
{
   ui_fill_rect( rect, colour, (ui_px[4]){ 4,4,4,4 } );
}

static void ui_outline( ui_rect rect, ui_px thickness, u32 colour )
{
   /* this if far from ideal but stops us from crashing */
   if( (vg_ui.cur_vert + 8 > vg_ui.max_verts) || 
       (vg_ui.cur_indice + 24 > vg_ui.max_indices))
      return;

   struct ui_vert *vertices = &vg_ui.vertex_buffer[ vg_ui.cur_vert ];
        u16            *indices  = &vg_ui.indice_buffer[ vg_ui.cur_indice ];

   for( int i=0; i<8; i++ ){
      vertices[i].uv[0] = 4;
      vertices[i].uv[1] = 4;
      vertices[i].colour = colour;
   }

        vertices[0].co[0] = rect[0];
        vertices[0].co[1] = rect[1];
        vertices[1].co[0] = rect[0]+rect[2];
        vertices[1].co[1] = rect[1];
        vertices[2].co[0] = rect[0]+rect[2];
        vertices[2].co[1] = rect[1]+rect[3];
        vertices[3].co[0] = rect[0];
        vertices[3].co[1] = rect[1]+rect[3];
   vertices[4].co[0] = vertices[0].co[0]-thickness;
   vertices[4].co[1] = vertices[0].co[1]-thickness;
   vertices[5].co[0] = vertices[1].co[0]+thickness;
   vertices[5].co[1] = vertices[1].co[1]-thickness;
   vertices[6].co[0] = vertices[2].co[0]+thickness;
   vertices[6].co[1] = vertices[2].co[1]+thickness;
   vertices[7].co[0] = vertices[3].co[0]-thickness;
   vertices[7].co[1] = vertices[3].co[1]+thickness;

        u16 start = vg_ui.cur_vert;
   u32 mesh[] = { 0,5,4, 0,1,5, 1,6,5, 1,2,6, 2,7,6, 2,3,7, 3,4,7, 3,0,4 };

   for( u32 i=0; i<vg_list_size(mesh); i++ ){
      indices[i] = start+mesh[i];
   }
        
        vg_ui.cur_indice += 24;
        vg_ui.cur_vert += 8;
}

static void ui_split_px( ui_rect rect, 
                         enum ui_axis other, ui_px width, ui_px pad,
                         ui_rect l, ui_rect r )
{
   enum ui_axis dir = other ^ 0x1;

   ui_rect temp;
   rect_copy( rect, temp );

   l[ dir ]     = temp[ dir ]   + pad;
   r[ dir ]     = temp[ dir ]   + width + (pad/2);
   l[ other ]   = temp[ other ] + pad;
   r[ other ]   = temp[ other ] + pad;
   l[ 2+dir ]   = width                   - ((3*pad)/2);
   r[ 2+dir ]   = temp[ 2+dir ]   - width - ((3*pad)/2);
   l[ 2+other ] = temp[ 2+other ] - pad*2;
   r[ 2+other ] = temp[ 2+other ] - pad*2;
}

static void ui_rect_center( ui_rect parent, ui_rect rect )
{
   rect[0] = parent[0] + (parent[2]-rect[2])/2;
   rect[1] = parent[1] + (parent[3]-rect[3])/2;
}

static void ui_fit_item( ui_rect rect, ui_px size[2], ui_rect d )
{
   i32 rp = (i32)rect[2] * (i32)size[1],
       rc = (i32)size[0] * (i32)rect[3];

   enum ui_axis dir, other;
   if( rc > rp ) dir = k_ui_axis_h;
   else          dir = k_ui_axis_v;
   other = dir ^ 0x1;

   d[2+dir] = rect[2+dir];
   d[2+other] = (rect[2+dir] * size[other]) / size[dir];

   ui_rect_center( rect, d );
}

static void ui_split_ratio( ui_rect rect, enum ui_axis dir, float ratio, 
                            ui_px pad, ui_rect l, ui_rect r )
{
   ui_px width = (float)rect[ 2+(dir^0x1) ] * ratio;
   ui_split_px( rect, dir, width, pad, l, r );
}

static void ui_rect_pad( ui_rect rect, ui_px pad )
{
   rect[0] += pad;
   rect[1] += pad;
   rect[2] -= pad*2;
   rect[3] -= pad*2;
}

static ui_px ui_text_line_width( const char *str )
{
   int length = 0;
   const char *_c = str;
   char c;

   while( (c = *(_c ++)) ){
      if( c >= 32 && c <= 126 )
         length ++;
      else if( c == '\n' )
         break;
   }

   return length * 8;
}

static ui_px ui_text_string_height( const char *str )
{
   int height = 1;
   const char *_c = str;
   char c;

   while( (c = *(_c ++)) ){
      if( c == '\n' ) height ++;
   }

   return height * 14;
}

static ui_px ui_text_aligned_x( const char *str, ui_rect rect, ui_px scale,
                                enum ui_align align )
{
   if( align == k_ui_align_left ){
      return rect[0];
   }
   else{
      ui_px width = ui_text_line_width( str ) * scale;

      if( align == k_ui_align_right )
         return rect[0] + rect[2]-width;
      else
         return rect[0] + (rect[2]-width)/2;
   }
}

static ui_px ui_min( ui_px a, ui_px b ){ return a<b?a:b; }
static ui_px ui_max( ui_px a, ui_px b ){ return a>b?a:b; }
static ui_px ui_clamp( ui_px a, ui_px min, ui_px max )
{
   return ui_min( max, ui_max( a, min ) );
}

static int ui_clip( ui_rect parent, ui_rect child, ui_rect clipped )
{
   ui_px parent_max[2], child_max[2];
   parent_max[0] = parent[0]+parent[2];
   parent_max[1] = parent[1]+parent[3];
   child_max[0] = child[0]+child[2];
   child_max[1] = child[1]+child[3];

   clipped[0] = ui_clamp( child[0], parent[0], parent_max[0] );
   clipped[1] = ui_clamp( child[1], parent[1], parent_max[1] );
   clipped[2] = ui_clamp( child_max[0], parent[0], parent_max[0] );
   clipped[3] = ui_clamp( child_max[1], parent[1], parent_max[1] );

   if( clipped[0] == clipped[2] ||
       clipped[1] == clipped[3] )
      return 0;

   clipped[2] -= clipped[0];
   clipped[3] -= clipped[1];
   
   return 1;
}

static int ui_inside_rect( ui_rect rect, ui_px co[2] )
{
   if( co[0] >= rect[0] &&
       co[1] >= rect[1] &&
       co[0] <= rect[0]+rect[2] &&
       co[1] <= rect[1]+rect[3] )
   {
      return 1;
   }
   else 
      return 0;
}

static int ui_click_down(void)
{
   if( vg_ui.ignore_input_frames ) return 0;

   if( (vg_ui.mouse_state[0] & SDL_BUTTON(SDL_BUTTON_LEFT)) &&
      !(vg_ui.mouse_state[1] & SDL_BUTTON(SDL_BUTTON_LEFT)) )
      return 1;
   else
      return 0;
}

static int ui_clicking(void)
{
   if( vg_ui.ignore_input_frames ) return 0;
   return vg_ui.mouse_state[0] & SDL_BUTTON(SDL_BUTTON_LEFT);
}

static int ui_click_up(void)
{
   if( vg_ui.ignore_input_frames ) return 0;
   if( (vg_ui.mouse_state[1] & SDL_BUTTON(SDL_BUTTON_LEFT)) &&
      !(vg_ui.mouse_state[0] & SDL_BUTTON(SDL_BUTTON_LEFT)) )
      return 1;
   else
      return 0;
}

static void ui_prerender(void)
{
   int x, y;
   vg_ui.mouse_state[1] = vg_ui.mouse_state[0];
   vg_ui.mouse_state[0] = SDL_GetMouseState( &x, &y );
   vg_ui.mouse[0] = x;
   vg_ui.mouse[1] = y;

        vg_ui.cur_vert = 0;
        vg_ui.cur_indice = 0;
   vg_ui.vert_start = 0;
   vg_ui.indice_start = 0;
   vg_ui.focused_control_hit = 0;

   if( vg_ui.ignore_input_frames ){
      vg_ui.ignore_input_frames --;
      return;
   }

   if( ui_click_down() ){
      vg_ui.mouse_click[0] = vg_ui.mouse[0];
      vg_ui.mouse_click[1] = vg_ui.mouse[1];
   }
}

static u32 ui_colour( enum ui_scheme_colour id )
{
   return vg_ui.scheme[ id ];
}

static void ui_text( ui_rect rect, const char *str, ui_px scale, 
                        enum ui_align align )
{
        ui_rect text_cursor;
        u32 colour = ui_colour( k_ui_fg ) & 0x00ffffff;
        
   const char *_c = str;
        u8 c;

   text_cursor[0] = ui_text_aligned_x( str, rect, scale, align );
        text_cursor[1] = rect[1];
        text_cursor[2] = 8*scale;
        text_cursor[3] = 14*scale;

   if( align & (k_ui_align_middle|k_ui_align_bottom) ){
      ui_px height = ui_text_string_height( str ) * scale;

      if( align & k_ui_align_bottom )
         text_cursor[1] += rect[3]-height;
      else
         text_cursor[1] += (rect[3]-height)/2;
   }

        while( (c = *(_c ++)) ){
                if( c == '\n' ){
                        text_cursor[1] += 14*scale;
         text_cursor[0] = ui_text_aligned_x( _c, rect, scale, align );
                        continue;
                }
                else if( c >= 33 ){
                        u8 glyph_base[2];
                        u8 glyph_index = c;
                        glyph_base[0] = glyph_index & 0xf;
                        glyph_base[1] = (glyph_index-glyph_base[0])>>4;
                        
                        glyph_base[0] *= 8;
                        glyph_base[1] *= 8;

         ui_rect rect_char;

         if( ui_clip( rect, text_cursor, rect_char ) ){
            ui_fill_rect( rect_char, colour, (ui_px[4])
            {
               glyph_base[0]+2,
               glyph_base[1]+1,
               glyph_base[0]+6,
               glyph_base[1]+8
            });
         }
                }
                else if( c == '\x1B' ){
         /* vt codes */
                        _c ++;
                        u16 colour_id = 0;
                        for( int i=0; i<3; i ++ ){
                                if( _c[i] ){
                                        if( _c[i] == 'm' ){
                                                _c = _c + i + 1;
                                                
                                                switch( colour_id ){
                   case '0':        colour = ui_colour( k_ui_fg ); break;
                   case '3'|'0'<<8: colour = ui_colour( k_ui_bg ); break;
                   case '3'|'1'<<8: colour = ui_colour( k_ui_red ); break;
                   case '3'|'2'<<8: colour = ui_colour( k_ui_green ); break;
                   case '3'|'3'<<8: colour = ui_colour( k_ui_yellow ); break;
                   case '3'|'4'<<8: colour = ui_colour( k_ui_blue ); break;
                   case '3'|'5'<<8: colour = ui_colour( k_ui_purple ); break;
                   case '3'|'6'<<8: colour = ui_colour( k_ui_aqua ); break;
                   case '3'|'7'<<8: colour = ui_colour( 0xffffffff ); break;
                                                }

                  colour &= 0x00ffffff;
                                                break;
                                        }
                                        
                                        colour_id |= _c[i] << (i*8);
                                } 
                                else{
                                        _c = _c +i;
                                        break;
                                }
                        }

         continue;
                }
      else if( c == '\t' ){
         text_cursor[0] += UI_GLYPH_SPACING_X*scale*4;
         continue;
      }
                
        text_cursor[0] += UI_GLYPH_SPACING_X*scale;
        }
}

static void ui_image( ui_rect rect, GLuint image )
{
   ui_flush( k_ui_shader_colour );

   glActiveTexture( GL_TEXTURE0 );
   glBindTexture( GL_TEXTURE_2D, image );
   ui_fill_rect( rect, 0xffffffff, (ui_px[4]){ 0,0, 255,255 } );
   ui_flush( k_ui_shader_image );
}

static u32 v4f_u32_colour( v4f colour )
{
   u32 r = colour[0] * 255.0f,
       g = colour[1] * 255.0f,
       b = colour[2] * 255.0f,
       a = colour[3] * 255.0f;

   return r | (g<<8) | (b<<16) | (a<<24);
}

static void ui_defocus_all(void)
{
   if( vg_ui.focused_control_type == k_ui_control_textbox ){
      SDL_StopTextInput();
   }

   vg_ui.focused_control_id = NULL;
   vg_ui.focused_control_hit = 0;
   vg_ui.focused_control_type = k_ui_control_none;
}

static int ui_button( ui_rect rect, enum ui_scheme_colour colour )
{
   int clickup= ui_click_up(),
       click  = ui_clicking() | clickup,
       target = ui_inside_rect( rect, vg_ui.mouse_click ) && click,
       hover  = ui_inside_rect( rect, vg_ui.mouse );

   u32 col_base      = vg_ui.scheme[ colour ],
       col_highlight = vg_ui.scheme[ k_ui_fg ],
       col_hover     = vg_ui.scheme[ colour + k_ui_brighter ];

   if( click ){
      if( target ){
         if( hover ){
            if( clickup ){
               ui_fill( rect, col_highlight );
               vg_ui.ignore_input_frames = 2;
               rect_copy( rect, vg_ui.click_fader );
               vg_ui.click_fade_opacity = 1.0f;
               ui_defocus_all();
               return 1;
            }
            else{
               ui_fill( rect, col_highlight );
               return 0;
            }
         }
         else{
            ui_fill( rect, col_base );
            ui_outline( rect, 1, col_highlight );
            return 0;
         }
      }
      else{
         ui_fill( rect, col_base );
         return 0;
      }
   }
   else{
      if( hover ){
         ui_fill( rect, col_hover );
         return 0;
      }
      else{
         ui_fill( rect, col_base );
         return 0;
      }
   }
}

static int ui_button_text( ui_rect rect, const char *string, ui_px scale,
                           enum ui_scheme_colour colour )
{
   int result = ui_button( rect, colour );
   ui_rect t = { 0,0, ui_text_line_width( string )*scale, 14*scale };
   ui_rect_center( rect, t );
   ui_text( t, string, scale, k_ui_align_left );
   return result;
}

static void ui_postrender(void)
{
   if( vg_ui.click_fade_opacity > 0.0f ){

      float scale = vg_ui.click_fade_opacity;
            scale = vg_maxf( 1.0f/255.0f, scale*scale );

      vg_ui.click_fade_opacity -= vg.time_frame_delta * 1.8f;
      u32 colour = v4f_u32_colour( (v4f){ 1.0f,1.0f,1.0f, scale } );

      ui_rect rect;
      rect[3] = (float)(vg_ui.click_fader[3]) * scale;
      rect[2] = vg_ui.click_fader[2];
      ui_rect_center( vg_ui.click_fader, rect );

      ui_fill( rect, colour );
   }
   ui_flush( k_ui_shader_colour );

   if( !vg_ui.focused_control_hit ){
      ui_defocus_all();
   }
}

static int ui_textbox( ui_rect rect, char *buf, u32 len )
{
   int clickup= ui_click_up(),
       click  = ui_clicking() | clickup,
       target = ui_inside_rect( rect, vg_ui.mouse_click ) && click,
       hover  = ui_inside_rect( rect, vg_ui.mouse );

   u32 col_base      = vg_ui.scheme[ k_ui_bg ],
       col_highlight = vg_ui.scheme[ k_ui_fg ];

   ui_px border = -1;

   if( vg_ui.focused_control_id == buf ){
      ui_fill( rect, col_base );
      ui_outline( rect, -2, vg_ui.scheme[ k_ui_orange ] );
      vg_ui.focused_control_hit = 1;
      return 0;
   }

   if( click ){
      if( target ){
         if( hover ){
            if( clickup ){
               ui_fill( rect, col_highlight );
               vg_ui.ignore_input_frames = 2;
               rect_copy( rect, vg_ui.click_fader );
               vg_ui.click_fade_opacity = 1.0f;
               vg_ui.focused_control_id = buf;
               vg_ui.focused_control_hit = 1;
               vg_ui.focused_control_type = k_ui_control_textbox;
               SDL_StartTextInput();
            }
            else{
               ui_fill( rect, col_highlight );
            }
         }
         else{
            ui_fill( rect, col_base );
            ui_outline( rect, -1, col_highlight );
         }
      }
      else{
         ui_fill( rect, col_base );
      }
   }
   else{
      ui_fill( rect, col_base );

      if( hover ){
         ui_outline( rect, -1, col_highlight );
      }
   }

   return 0;
}

#endif /* VG_IMGUI_H */