Sinf.org

OpenGL Terrain Rendering

Tue, 09 Dec 2025 21:09:06 +0200

Desert rendered from height map

OpenGL Instancing

Tue, 03 Jun 2025 15:03:43 +0200

PomodoroLog different views

Sun, 18 May 2025 15:03:51 +0200

Preview of PomodoroLog

PomodoroLog Themes

Wed, 14 May 2025 15:03:09 +0200

Various color themes for PomodoroLog.

Pomodoro mini projects

Thu, 01 May 2025 15:03:26 +0200

Small pomodoro timer project

PowerUps

Sat, 08 Feb 2025 15:03:49 +0200

Added power ups to PlanetSweeper.

Menu System

Tue, 21 Jan 2025 15:03:07 +0200

Main menu and game selection for PlanetSweeper.

Tile animation and explosions

Sun, 13 Oct 2024 02:02:24 +0200

Various tile and explosion effects.

Bloom

Mon, 30 Sep 2024 02:02:56 +0200

Graphics progress

Mon, 23 Sep 2024 16:04:10 +0200

Progress over the last few months

Better light and colors

Mon, 16 Sep 2024 15:03:53 +0200

Same scene from before but with better lighting.

Engine Demo

Sun, 01 Sep 2024 15:03:54 +0200

A small demo of engine for diffent game type.

Splash Screen

Sun, 30 Jun 2024 15:03:37 +0200

Implemented a splash screen on startup.

Basic Minesweeper Gameplay

Wed, 19 Jun 2024 15:03:56 +0200

Player Headlights

Wed, 12 Jun 2024 15:03:33 +0200

Shadow Rendering

Wed, 05 Jun 2024 15:03:56 +0200

Better Colors

Sun, 26 May 2024 15:03:04 +0200

Planet Models

Fri, 17 May 2024 15:03:13 +0200

Skeleton Animation

Mon, 06 May 2024 15:03:23 +0200

Settings Menu Demo

Sun, 14 Apr 2024 15:03:28 +0200

OpenGL Polyhedron

Sun, 07 Apr 2024 01:31:42 +0200

glUniformLocation Benchmark

Tue, 23 Jan 2024 01:00:38 +0200

I was looking for some information on whether or not calling glUniformLocation for every frame has any performance impact. Everything I found was either claims without any sources or very old data.

Since I couldn’t find anything useful, I ended up writing a small benchmark program to test 3 different ways of using uniform locations:

Calling glUniformLocation every time (Lookup).
Getting the location at first call and caching it in a std::map using compile time keys (Cached).
Getting the location at load time and storing the location in a variable (Static).

The test uses a shader with 20 vec4 uniforms (10 in vertex, 10 in fragment) and sets each uniform 50 times per render (less than 50 times made it hard to measure the time delta) with 1000 renders per run to come up with an average time.

Here are the results of a modern high-end desktop and 5 year old laptop both running Windows 11.

Machine / Method	First	Second	Fastest	Slowest	Average
NVIDIA RTX4090
- Lookup	1423	1047	578	2317	929
- Cached	366	147	105	402	134
- Static	159	21	5	167	10
i7-8565U / UHD 620
- Lookup	1300	1115	870	1984	1043
- Cached	676	671	488	1849	579
- Static	130	129	73	459	103

Numbers are in μs/microseconds based on 5 runs of the benchmark program for each machine/method combination. The first frame value for “cached” is misleading since it loops all 20 variable 50 times so only needs to call glUniformLocation for 2% of the calls. With 1000 unique uniform values the first frame would likely be similar to “lookup” results.

The difference is pretty significations. If running at 60 fps with 1000 uniforms then looking up the location every frame would use up 5.6% of the frame time on average vs only 0.1-0.6% (depending on hardware) when storing the location.

The idea of caching locations in a std::map worked better than lookup but still significantly worse than using a custom class with uniform variables hardcoded.

Benchmark source code available here.

ArcRace Update

Fri, 19 Jan 2024 00:56:36 +0200

A small update to my 3D game demo to test some shader and model loading code.

Download (2.4MB, Windows 10/11)

Libraries

GLFW: Window, OpenGL context, and keyboard input
Galogen: OpenGL API headers
GLM: Vector and matrix math
std_image: Texture loading
SoLoud: Sound playback
JSON for Modern C++: Parsing JSON in GLTF models.

Music & Sound FX

OpenGL Text using stb_truetype

Thu, 11 Jan 2024 00:47:58 +0200

A quick on using stb_truetype.h to render text in OpenGL using an alpha mask texture with the stbtt_PackBegin/stbtt_PackFontRage API.

First load the font. The important data is the pixel data for the texture and packed character data. The example below packs characters from codepoints 0 to 125. If a different starting point than 0 is used then lookups in charData array must be offset by that number. (With 0-125 uppercase A will be at charData[65], with 32-125 then A is at charData[65-32]).

stbtt_pack_context packContext;
stbtt_packedchar charData[126];
unsigned char pixels[TEXTURE_WIDTH * TEXTURE_HEIGHT];
tbtt_PackBegin(&packContext, pixels, 
               TEXTURE_WIDTH, TEXTURE_HEIGHT,
               TEXTURE_WIDTH, 1, NULL);
stbtt_PackFontRange(&packContext, (unsigned char*)ttfData, 0, TEXTURE_FONT_SIZE,
                    0, 125, charData);
stbtt_PackEnd(&packContext);

Then put the pixel data into an OpenGL texture. The data is a single channel monochrome color:

glTexImage2D(GL_TEXTURE_2D, 0, GL_R8,
             TEXTURE_WIDTH, TEXTURE_HEIGHT, 0,
             GL_RED, GL_UNSIGNED_BYTE, pixels);

To render text, lookup each character in the charData array to get the position in the texture as char.x0, char.x1, char.y0, char.y1. The actual size of the character can be calculated from the offsets as char.xoff2 - char.xoff and char.yoff2 - char.yoff. The xoff values are the start and end offset from the left. Yoff are the start and end offset from the baseline (y values will be negative when above the baseline, positive when below). The x distance to the next character is available in char.xadvance. This can also be used to calculating the full width of a string before rendering for things like scaling to fit or center/right aligning text.

MIT licensed demo code available here.

ArcRace Mini Game

Sun, 31 Dec 2023 15:24:13 +0200

📝 An updated version 1.1 is now available here.

A small game demo made to refresh OpenGL and general 3D programming.

Download (2.4MB, Windows 10/11)

Libraries

GLFW: Window, OpenGL context, and keyboard input
Galogen: OpenGL API headers
GLM: Vector and matrix math
std_image: Texture loading
SoLoud: Sound playback