VBah

A graphic library in Bah, built on Glut, OpenGL and freetype2.

This uses the OpenGL coordinates system. [0.0;0.0] is the center of the window.

You can install vbah using bpm -install ithirzty/vbah

The window borders can change, if the window is resized or does not have an aspect ratio of 1:1. To get the current window's borders, use:

• window.lb the left border (smallest x coordinate),
• window.rb the right border (biggest x coordinate),
• window.bb the bottom border (smallest y coordinate),
• window.tb the top border (biggest y coordinate).

Usage

Note that this includes libraries that are typically shared. You will need to add the -d option to compile your program.

Step 1 - Dependencies

Make sure you have OpenGL and Glut C libraries installed.

Step 2 - Writting code

Make a new program main.bah.

#include "include.bah"
#include "vbah.bah"

win window*

display() {
    drawCircle(0.0, 0.0, 0.05, rgb(1.0, 1.0, 1.0))
}

main(args []cpstring) int {
    win = window(600, 600, "My window")
    win.display = display
    win.launch()
    return 0
}

Step 3 - Compiling

Compile your program, bah main.bah -d.

Useful functions

• vec(x float, y float) vec makes a vector (2d point),
• vec4(x1 float, y1 float, x2 float, y2 float) vec makes a 4 components vector (can be used as identity matrix for matrix transformations),
• rgb(r float, g float, b float) rgb makes a rgb struct,
• rgbTexture(path cpstring, w int, h int) rgb makes a rgb struct from a BMP image path,
• setDrawingColor(color rgb) bool sets the current drawing color/texture from a rgb struct,
• drawCircle(v vec, radius float, color rgb) draws a circle,
• drawBox(v vec, w float, h float, color rgb) draws a box (rectangle),
• drawShape(shape []float, color rgb) draws a custom shape,
• drawText(v vec, color rgb, font ptr, str cpstring) draws text,
• clearFrame() clears the screen (this is automatically done at each frame if window.autoClear == true as it is by default),
• redrawFrame() ask the scheduler to redraw a frame (this is automatically done at idle is window.autoLoop == true as it is by default),
• sendFrame() send the frame (this is automatically done after the window.display function is returned),
• pixelsToCoords(v vec*) translates pixel coordinates to window coordinates (useful for mouse callbacks),
• pixelsDimToCoords(v vec*) translates pixel dimension to window coordinates dimension (useful for text handling),
• window(w int, h int, t cpstring) window* used for making a window,
• minCoords(v vec*, shape []float) used for getting the lower-left coordinate of a shape's bounding box,
• maxCoords(v vec*, shape []float) used for getting the upper-right coordinate of a shape's bounding box,
• dot(v1 vec, v2 vec) float used for getting the dot product of two vectors,
• translateShape(v vec, shape []float) used for translating a shape,
• circleFromShape(v vec*, rad float*, shape []float) used for getting the circle bounding box of a shape,
• degToRad(d float) float used for converting degrees in radians,
• rotateShape(rot float, shape []float) used for rotating a shape by an ammount of degrees,
• detectCollideCircle(v1 vec, rad1 float, v2 vec, rad2 float) bool used for detecing collision between two circle bounding boxes,
• centerCoords(v vec*, shape []float) used for getting the centroid of a shape,
• drawLine(v1 vec, v2 vec, w float, color rgb) used for drawing a line,
• setMarkupColor(pos uint, color rgb, m []textMarkup) used for adding a color at specified position in a textMarkup array,
• makeTexture(w int, h int) rgb used for making a new blank and writable texture.

The window structure

Thw window structures allows you to manipulate the current window, such as launching it, setting its callbacks, getting its delta time (time to render last frame in second as float)...

Its usefull fields are:

• width: int the window's width (will update on resize),
• height: int the window's height (will update on resize),
• x: int the window's x coordinate as it is launched,
• y: int the window's y coordinate as it is launched,
• title: cpstring the window's title as it is launched,
• autoClear: bool weither the frame should be automatically cleared at each frame,
• autoLoop: bool weither a new frame should be scheduled after the last one finished,
• delta: float the time in second as float that the last frame took to render,
• fullscreened: bool weither the window is in fullscreen mode.
• lb: float = -1.0 left border (smallest x coordinate),
• tb: float = 1.0 top border (biggest y coordinate),
• rb: float = 1.0 right border (biggest x coordinate),
• bb: float = -1.0 bottom border (smallest y coordinate).

Its callbacks are:

• display: function() called to draw a new frame,
• idle: function() called when the scheduler has nothing to do,
• init: function() called after the window is launched,
• click: function(int, bool, int, int) called when the mouse is clicked,
• move: function(int, int) called when the mouse is passively moved,
• drag: function(int, int) called when the mouse is draged (button clicked while moving),
• keyboard: function(char, int) called when a key is pressed on the keyboard the char beeing the key and the int the modifer (shift, crtl, alt...),
• keyboardSpecial: function(int) called when a special key is pressed on the keyboard (f[n] keys, arrows...).

Its methods are:

• launch() launches the window,
• fps() int returns the current number of frames per second,
• getWidth() int returns the width of the window in pixels deprecated, use the width field instead,
• getHeight() int returns the height of the window in pixels deprecated, use the height field instead,
• fullscreen() makes the window fullscreenned.

The font structure

The font structures allows you to manipulate TTF text fonts.

Its methods are:

• load(path cpstring) loads the font at the specified path,
• setSize(s int) sets the text size,
• write(pos vec, color rgb, str cpstring) writes text at the specified coordinates with the specified color,
• writeMarkup(pos vec, colors []textMarkup, offset int, str cpstring) same as .write() but with a textMarkup array instead of rgb color,
• calcWidth(s cpstring) int calculates the width of a string as pixels value,
• getHeight() uint returns the maximum height of a char.

Its fields are:

• lineSpacing the vertical margin between each line,
• antialiased weither the font should be anti-aliased.

The sound structure

The sound structures allows you to play sound.

Its methods are:

• load(path cpstring) loads the sound at the specified path,
• play() plays the sound.

The animation / animationFrames structure

Theses allows you to keep track of animation of an element.

animationFrames is composed of two vectors (from and to) and a duration.
You can use set(from vec, to vec, d float) to set it up and get(delta float) vec to generate a new frame using the window's delta time.

animation is like a playlist of animationFrames.
Animation frames are stored in .animations field and you can use get(delta float) vec to generate a new frame using the window's delta time.

The rgb structure

This is a structure that contains either an rgb color or a texture. You can generate a rgb color using rgb(r,g,b). You can generate a texture using makeTexture(w,h) or rgbTexture(path, w, h).

Its methods are:

• drawTo(drawFn function(ptr), arg ptr) to draw to the texture where drawFn is the function that will be used to draw to it and arg the argument that will be passed to it.

Vectors

The vector structure vec can be used as a 2d point/vector, generated by vec() or as a 2x2 matrix generated by vec4().

Linear transformations

Let an identity matrix mat be mat = vec4(0.0, -1.0, 1.0, 0.0) (a 90 degrees clockwise rotation).

Let a vector point be point = vec(0.5, 0.5) (midway to the top right corner).

Let a vector point2 be point2 = mat * point (note that the order of the operand is not important).

The vector point2 is now the result of a 90 degrees clockwise rotation of the vector point arround the origin.

Examples

• Particles, a simple particle system.
  
• Bricks, a simple bricks game
  
• Textures, a demonstration of loading textures.
  
• Mouse, a demonstration of mouse callbacks.
  
• Shape, a demonstration of custom shapes drawing
  
• Text, a demonstration of writting text