GLFW & OpenGL learnings

glfw-opengl-learnings.md

General Introduction into OpenGL

• https://open.gl/introduction looks very good

Double Buffering (from http://www.glfw.org/docs/latest/quick.html)

GLFW windows by default use double buffering. That means that each window has two rendering buffers; a front buffer and a back buffer. The front buffer is the one being displayed and the back buffer the one you render to.

When the entire frame has been rendered, the buffers need to be swapped with one another, so the back buffer becomes the front buffer and vice versa.

glfwSwapBuffers(window);

RGBA colors (from https://www.opengl.org/sdk/docs/man2/xhtml/glColor.xml)

void glColor4i(	GLint  	red,
 	GLint  	green,
 	GLint  	blue,
 	GLint  	alpha);

Depth buffer (from https://open.gl/depthstencils, but also on https://www.opengl.org/archives/resources/faq/technical/depthbuffer.htm)

glEnable(GL_DEPTH_TEST);

general information about what a depth-/z-buffer is: https://de.wikipedia.org/wiki/Z-Buffer

Clear Buffers (from https://www.opengl.org/discussion_boards/showthread.php/128606-how-to-clear-screen-after-drawing)

glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // clear colors to black
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // apply cleared color buffer & clear the depth buffer

Set matrix mode (from https://www.opengl.org/sdk/docs/man2/xhtml/glMatrixMode.xml)

void glMatrixMode(	GLenum mode);

Drawing with OpenGL

Good tutorial: https://wiki.delphigl.com/index.php/glBegin