Debug Drawing Text using Lines
08/04/2025
It's more than once in my life that I've wanted to debug draw some text in a game scene, but for whatever reason the game engine I'm using either doesn't support debug drawing text directly in the scene, makes it unnecessarily difficult, or doing so interferes with the rest of the rendering in a nasty way.
Yet most game engines do support fairly nice and efficient debug drawing of lines, often supporting some kind of thickness, depth testing, and sometimes things like transparency too.
I thought it would probably be possible to draw text using just line rendering, figuring I could build a basic look-up table that mapped character codes to a series of line segments. I'm certain this isn't a new idea, but surprisingly I couldn't find much after some digging around online.
Well here's the look-up table(s) I ended up generating to do this. The line segments roughly follow the shapes of Consolas hence Consolines.
static const char consolines_nums[94] = {
2, 6, 4, 10, 15, 16, 4, 5, 5, 3, 2, 3, 1, 1, 1, 13, 3, 6,
11, 4, 8, 13, 2, 14, 15, 2, 4, 2, 2, 2, 7, 28, 3, 12, 10, 9,
4, 3, 11, 3, 3, 5, 4, 2, 4, 3, 12, 7, 15, 8, 12, 2, 6, 2,
4, 2, 3, 3, 3, 1, 3, 2, 1, 1, 11, 10, 8, 10, 12, 5, 26, 6,
4, 6, 4, 3, 11, 6, 10, 9, 9, 5, 10, 5, 6, 2, 4, 2, 4, 3,
10, 1, 10, 7
};
static const int consolines_offsets[94] = {
0, 2, 8, 12, 22, 37, 53, 57, 62, 67, 70, 72, 75, 76,
77, 78, 91, 94, 100, 111, 115, 123, 136, 138, 152, 167, 169, 173,
175, 177, 179, 186, 214, 217, 229, 239, 248, 252, 255, 266, 269, 272,
277, 281, 283, 287, 290, 302, 309, 324, 332, 344, 346, 352, 354, 358,
360, 363, 366, 369, 370, 373, 375, 376, 377, 388, 398, 406, 416, 428,
433, 459, 465, 469, 475, 479, 482, 493, 499, 509, 518, 527, 532, 542,
547, 553, 555, 559, 561, 565, 568, 578, 579, 589
};
static const int consolines_lines[596] = {
0x701F3C1F, 0x2A1F281F, 0x59135206, 0x63175913, 0x6D116317, 0x59305223,
0x63345930, 0x6D2E6334, 0x563A5608, 0x3B373B05, 0x6A172610, 0x26276A2E,
0x27222909, 0x2D2F2722, 0x35342D2F, 0x3E313534, 0x510F3E31, 0x590B510F,
0x620E590B, 0x681A620E, 0x6730681A, 0x19187425, 0x26077038, 0x6D096105,
0x70156D09, 0x671D7015, 0x5B1B671D, 0x55125B1B, 0x59085512, 0x61055908,
0x3D263122, 0x40323D26, 0x373A4032, 0x2B38373A, 0x252F2B38, 0x2925252F,
0x31222925, 0x2538590E, 0x55265F2B, 0x610D590E, 0x6A12610D, 0x6E1C6A12,
0x6B266E1C, 0x662A6B26, 0x5F2B662A, 0x3F085526, 0x2A282519, 0x290F2519,
0x2F09290F, 0x37062F09, 0x3F083706, 0x39332A28, 0x46343933, 0x6E1D6621,
0x5D226621, 0x541A5D22, 0x5210541A, 0x5C1B722B, 0x49165C1B, 0x37164916,
0x271B3716, 0x102B271B, 0x5C247214, 0x49295C24, 0x37294929, 0x27243729,
0x10142724, 0x70204620, 0x65324E0D, 0x650E4F32, 0x291F5A1F, 0x42074238,
0x2423301D, 0x191E2423, 0x1310191E, 0x422D4212, 0x2A1F2C1F, 0x70301A0C,
0x5A35360A, 0x4A08360A, 0x5F0D4A08, 0x66145F0D, 0x6A206614, 0x652C6A20,
0x5A35652C, 0x46375A35, 0x31324637, 0x2B2B3132, 0x261F2B2B, 0x2B13261F,
0x360A2B13, 0x2735270D, 0x6A222722, 0x5E0C6A22, 0x270B2735, 0x502F270B,
0x5C30502F, 0x672A5C30, 0x6B1D672A, 0x630D6B1D, 0x2625270C, 0x2F2F2625,
0x38332F2F, 0x40313833, 0x49224031, 0x522C4922, 0x5C2F522C, 0x652B5C2F,
0x6A1D652B, 0x670E6A1D, 0x49164922, 0x37053739, 0x262B6A2B, 0x6A233705,
0x6A2B6A23, 0x680F6830, 0x4A0F680F, 0x4A274A0F, 0x270D261F, 0x2E2E261F,
0x3A322E2E, 0x442F3A32, 0x4A27442F, 0x671E6930, 0x5E12671E, 0x4E0C5E12,
0x460B4E0C, 0x360C460B, 0x460B4D1D, 0x2914360C, 0x25212914, 0x2A2E2521,
0x35352A2E, 0x43333535, 0x4C294333, 0x4D1D4C29, 0x6935690A, 0x26156935,
0x67125C0C, 0x6B206712, 0x662E6B20, 0x5C32662E, 0x522E5C32, 0x3E0E522E,
0x350B3E0E, 0x2813350B, 0x261F2813, 0x2A2D261F, 0x32332A2D, 0x3C313233,
0x53103C31, 0x5C0C5310, 0x2920270D, 0x322D2920, 0x3E32322D, 0x4C333E32,
0x4C334529, 0x5F304C33, 0x67295F30, 0x6A1E6729, 0x66126A1E, 0x5E0B6612,
0x550A5E0B, 0x4A0D550A, 0x44144A0D, 0x421E4414, 0x4529421E, 0x531F561F,
0x291F2C1F, 0x531F561F, 0x23242E1E, 0x181E2324, 0x1311181E, 0x420D262E,
0x5C2D420D, 0x4C354C0B, 0x380A3835, 0x42312610, 0x5C114231, 0x3B1B4A1B,
0x4D2A4A1B, 0x59304D2A, 0x622D5930, 0x6B22622D, 0x6E146B22, 0x271B2A1B,
0x0F25122D, 0x0E1C0F25, 0x12100E1C, 0x1F071210, 0x34041F07, 0x4B063404,
0x5E0C4B06, 0x6C185E0C, 0x70246C18, 0x6D2F7024, 0x65366D2F, 0x563A6536,
0x483B563A, 0x3538483B, 0x2B333538, 0x292E2B33, 0x2C29292E, 0x37282C29,
0x2D203728, 0x4F2B3728, 0x53274F2B, 0x54225327, 0x4E195422, 0x41154E19,
0x32144115, 0x2B173214, 0x291B2B17, 0x2D20291B, 0x6A1F2606, 0x26396A1F,
0x3832380D, 0x6A0D260D, 0x672B6A0D, 0x490D4924, 0x260D292C, 0x3032292C,
0x39353032, 0x40323935, 0x49244032, 0x502E4924, 0x5932502E, 0x61305932,
0x672B6130, 0x26272A35, 0x29182627, 0x30102918, 0x390C3010, 0x460A390C,
0x560C460A, 0x6112560C, 0x691E6112, 0x6A27691E, 0x66356A27, 0x690A260A,
0x6920690A, 0x260A2620, 0x632C6920, 0x5933632C, 0x49375933, 0x39344937,
0x2E2E3934, 0x26202E2E, 0x260F2632, 0x690F260F, 0x6932690F, 0x490F4931,
0x6A102510, 0x6A326A10, 0x4810482F, 0x48354823, 0x28354835, 0x6A276635,
0x67196A27, 0x5D0E6719, 0x4A085D0E, 0x3C094A08, 0x300E3C09, 0x2819300E,
0x26252819, 0x28352625, 0x6B0A240A, 0x4936490A, 0x24366B36, 0x2633260C,
0x6933690C, 0x261F691F, 0x692D690E, 0x312D692D, 0x2A25312D, 0x261B2A25,
0x2A0D261B, 0x6A0D250D, 0x49176A32, 0x25334917, 0x490D4917, 0x26126A12,
0x26342612, 0x6A0B2507, 0x3F1F6A0B, 0x6A353F1F, 0x25386A35, 0x6B0C250C,
0x24356B0C, 0x6A352435, 0x662D6A20, 0x5E33662D, 0x4C385E33, 0x39354C38,
0x2C2E3935, 0x26202C2E, 0x28142620, 0x340A2814, 0x4707340A, 0x580A4707,
0x6613580A, 0x6A206613, 0x6A0D260D, 0x420D4226, 0x4A304226, 0x56354A30,
0x632F5635, 0x6A1F632F, 0x6A0D6A1F, 0x122B153A, 0x1E1F122B, 0x251F1E1F,
0x2B2D251F, 0x3C362B2D, 0x49383C36, 0x59354938, 0x662D5935, 0x6A20662D,
0x64116A20, 0x560A6411, 0x4707560A, 0x360A4707, 0x2A12360A, 0x251F2A12,
0x6A0D250D, 0x6A206A0D, 0x652C6A20, 0x5A31652C, 0x512F5A31, 0x512F4822,
0x480D4822, 0x25344822, 0x6A20682F, 0x67136A20, 0x610D6713, 0x5A0B610D,
0x520E5A0B, 0x4A1A520E, 0x412E4A1A, 0x3D32412E, 0x35343D32, 0x2D303534,
0x26222D30, 0x280A2622, 0x69396908, 0x261F691F, 0x340B6A0B, 0x6A353435,
0x2A10340B, 0x251F2A10, 0x292B251F, 0x3435292B, 0x251F6A06, 0x6A3A251F,
0x260E6A06, 0x511F260E, 0x2634511F, 0x6A382634, 0x6A352508, 0x6A0A2536,
0x40206A06, 0x6A394020, 0x25204020, 0x6936690B, 0x26096936, 0x26362609,
0x7117712C, 0x0F177117, 0x0F2C0F17, 0x1933700E, 0x71287112, 0x0F287128,
0x0F130F28, 0x6A1F4B0C, 0x4B336A1F, 0x0F3C0F03, 0x681D7013, 0x560F5920,
0x4E312531, 0x562C4E31, 0x5920562C, 0x3F153F31, 0x370D3F15, 0x2F0B370D,
0x26112F0B, 0x251B2611, 0x2825251B, 0x32312825, 0x290D6F0D, 0x251C290D,
0x2728251C, 0x36332728, 0x43353633, 0x50314335, 0x562C5031, 0x5924562C,
0x551B5924, 0x4B0D551B, 0x59255632, 0x55185925, 0x4A0F5518, 0x3F0C4A0F,
0x330F3F0C, 0x2819330F, 0x26252819, 0x29322625, 0x25317031, 0x27213731,
0x25192721, 0x29112519, 0x310C2911, 0x3E0A310C, 0x4E0E3E0A, 0x55154E0E,
0x59215515, 0x53315921, 0x4035400B, 0x4B334035, 0x532F4B33, 0x5728532F,
0x59205728, 0x56155920, 0x4C0D5615, 0x400B4C0D, 0x320D400B, 0x2815320D,
0x25242815, 0x28332524, 0x661B261B, 0x6E397027, 0x6D20661B, 0x70276D20,
0x4F074F37, 0x58285837, 0x512E5828, 0x591C5828, 0x5411591C, 0x4A0D5411,
0x3D124A0D, 0x391E3D12, 0x370E3D12, 0x310C370E, 0x2B0F310C, 0x28142B0F,
0x282A2814, 0x220C2814, 0x2532282A, 0x21352532, 0x1C362135, 0x16331C36,
0x122D1633, 0x0E1E122D, 0x110F0E1E, 0x150A110F, 0x1B09150A, 0x220C1B09,
0x3C2A391E, 0x47303C2A, 0x512E4730, 0x250D700D, 0x25324F32, 0x5519490D,
0x59235519, 0x562D5923, 0x4F32562D, 0x2634260D, 0x57212621, 0x570E5721,
0x6A1F6D1F, 0x6A296D29, 0x572B570D, 0x1E2B572B, 0x0E16110A, 0x11220E16,
0x1E2B1122, 0x250F700F, 0x411B410F, 0x5932411B, 0x2533411B, 0x2633260D,
0x6F212621, 0x6F0E6F21, 0x25085808, 0x25204C20, 0x25365136, 0x56134808,
0x59195613, 0x551E5919, 0x4C20551E, 0x572A4C20, 0x5930572A, 0x57345930,
0x51365734, 0x580D250D, 0x25324E32, 0x54174A0D, 0x59245417, 0x542F5924,
0x4E32542F, 0x500E3E09, 0x591D500E, 0x552E591D, 0x4834552E, 0x35354834,
0x292C3535, 0x251F292C, 0x2A11251F, 0x330B2A11, 0x3E09330B, 0x570D0E0D,
0x571C490D, 0x5925571C, 0x54305925, 0x43355430, 0x31324335, 0x28283132,
0x251D2828, 0x290D251D, 0x0F315531, 0x591F5531, 0x5312591F, 0x400A5312,
0x2E0D400A, 0x27132E0D, 0x251B2713, 0x2B26251B, 0x37312B26, 0x570F250F,
0x571F480F, 0x5928571F, 0x55325928, 0x49355532, 0x5921572F, 0x56145921,
0x4D0F5614, 0x44134D0F, 0x3B2B4413, 0x36303B2B, 0x30323630, 0x292C3032,
0x251D292C, 0x280D251D, 0x69173317, 0x2A1B3317, 0x26272A1B, 0x27342627,
0x58345806, 0x2F0D580D, 0x26325932, 0x28132F0D, 0x251B2813, 0x2A26251B,
0x34322A26, 0x251F5809, 0x5835251F, 0x25115806, 0x4A1F2511, 0x24314A1F,
0x58382431, 0x5833250B, 0x580D2534, 0x171A5935, 0x1113171A, 0x10071113,
0x241F580A, 0x5831580D, 0x260C5831, 0x2634260C, 0x6F24712F, 0x671D6F24,
0x4E1D671D, 0x48194E1D, 0x430C4819, 0x3F19430C, 0x371E3F19, 0x1B1E371E,
0x13221B1E, 0x0F2F1322, 0x0F1F7C1F, 0x6F1A710F, 0x67216F1A, 0x4E216721,
0x48254E21, 0x43324825, 0x3F254332, 0x37203F25, 0x1B203720, 0x131C1B20,
0x0F0F131C, 0x450A3D08, 0x4A13450A, 0x431E4A13, 0x3B27431E, 0x392D3B27,
0x3F35392D, 0x47373F35
};
It contains line segments for all the 95 printable ASCII characters (not including the space character), so starting with ! and ending with ~. Line segment are encoded by taking the four integer coordinates (start_x, start_y, end_x, end_y) with values ranging from 0-128, and packing them into a single 32-bit integer. The aspect ratio of characters is 1:2.
Here is how you might use this table to render text in raylib (for example):
void DrawDebugText3D(
const char* string,
Vector3 location,
Quaternion rotation,
Color color,
float thick, // Thickness. Set to 0.0f for pixel lines.
float scale, // Overall scale. Default to 1.0f
float width, // Width. Default to 1.0f
float height, // Height. Default to 1.0f
float spacing, // Character Spacing. Default to 0.0f
float lineheight) // Line Spacing. Default to 1.0f
{
int slen = strlen(string);
float xOffset = 0.0;
float yOffset = 0.0;
for (int i = 0; i < slen; i++)
{
if (string[i] == '\n')
{
// If we have a line break then reset xOffset and move to next line
xOffset = 0.0;
yOffset -= lineheight * scale * height;
}
else if (string[i] == '\r')
{
// Carriage return resets the xOffset
xOffset = 0.0;
}
else if (string[i] == '\t')
{
// Tab is like four spaces
xOffset += 4.0f * 0.5f * scale * width + spacing;
}
else if (string[i] < '!' || string[i] > '~')
{
// Every other non-printable character is rendered as a space
xOffset += 0.5f * scale * width + spacing;
}
else
{
// Get the look-up table index from the character code
int ci = string[i] - '!';
// Get the number of line segments and the offset into the lines array
int lnum = consolines_nums[ci];
int loff = consolines_offsets[ci];
for (int li = 0; li < lnum; li++)
{
// Unpack integer coordinates
int xStartInt = (0x000000FF & (consolines_lines[loff + li] >> 0));
int yStartInt = (0x000000FF & (consolines_lines[loff + li] >> 8));
int xEndInt = (0x000000FF & (consolines_lines[loff + li] >> 16));
int yEndInt = (0x000000FF & (consolines_lines[loff + li] >> 24));
// Compute the line start position in 3D space
Vector3 start = (Vector3){
xOffset + scale * width * ( ((float)xStartInt) / 128),
yOffset - scale * height * (1.0f - ((float)yStartInt) / 128),
0.0f };
start = Vector3Add(
Vector3RotateByQuaternion(start, rotation), location);
// Compute the line end position in 3D space
Vector3 end = (Vector3){
xOffset + scale * width * ( ((float)xEndInt) / 128),
yOffset - scale * height * (1.0f - ((float)yEndInt) / 128),
0.0f };
end = Vector3Add(
Vector3RotateByQuaternion(end, rotation), location);
// If thickness is zero draw as a line otherwise draw as a capsule
if (thick == 0.0f)
{
DrawLine3D(start, end, color);
}
else
{
DrawCapsule(start, end, thick, 5, 2, color);
}
}
// Shift forward to next location
xOffset += 0.5f * scale * width + spacing;
}
}
}
And here is what it looks like in action:
As you can see, for non-zero-thickness lines it draws capsules, which produces a really nice effect.
You can find the PSD file, SVG file, and the quick and dirty Python script I used for making the look-up table here.