#Connect 4 dots using 3 lines code

Here, the sizes array contains two elements that contain the smallest and largest valid value for glPointsize. GlGetFloatv(GL_POINT_SIZE_GRANULARITY,&step) Get supported point size range and step size GLfloat step // Store supported point size increments

#Connect 4 dots using 3 lines code

Use the following code to get the range of point sizes and the smallest interval between them: GLfloat sizes // Store supported point size range Not all point sizes are supported, however, and you should make sure the point size you specify is available.

$connect 4 dots using 3 lines$

The glPointSize function takes a single parameter that specifies the approximate diameter in pixels of the point drawn. You can change the default point size by calling glPointSize. By default, points are one pixel in size. Each vertex specified is simply a single point on the screen. You can also use the arrow keys to rotate the rendering on the x and y axes. Start the program and press the space bar to progress from GL_POINTS to GL_TRIANGLE_STRIP. The example program Primitives demonstrates rendering each one of these.

Triangles fan out from an origin, sharing adjacent vertices. Same as GL_LINE_STRIP, but the last and first vertex are connected.Įvery three vertices define a new triangle. OpenGL Geometric PrimitivesĮach vertex is a single point on the screen.Įach pair of vertices defines a line segment.Ī line segment is drawn from the first vertex to each successive vertex. Table 3.2 lists these seven primitives and briefly describes their purpose. Essentially, all the vertices in a given batch are assembled into one of these primitives. Primitives are rendered in a single batch that contain all the vertices and associated attributes for a given primitive. To start drawing solid geometry, we use seven geometric primitives defined by OpenGL. It is the job of your shader program and rasterization hardware to get your points, lines, and triangles projected from your established 3D space to the 2D image seen on your computer screen. You're not concerned with physical screen coordinates and pixels, but rather positional coordinates in your viewing volume. With OpenGL, however, drawing on the computer screen is fundamentally different. Then build on this simple concept, using your favorite computer language to produce lines, polygons, circles, and other shapes and graphics-perhaps even a GUI. This is computer graphics at its simplest: Draw a point somewhere on the screen and make it a specific color. A pixel is the smallest element on your computer monitor, and on color systems that pixel can be any one of many available colors. When (and if) you first learned to draw any kind of 2D graphics on any computer system, you probably started with pixels. OpenGL SuperBible: Comprehensive Tutorial and Reference, 5th Edition