How z-buffer( depth buffer) for 3D object rendering.

Z buffer plays an important role to draw 3D objects. Z buffer( depth buffer) holds the depth of each pixel.

Consider two objects with different z values, and some portion of one object and some portion of one object overlap with other. When first object drawn, its corresponding z values( the distance between view point and object) are updated in z-buffer and the pixel values(RGB) are updated in color buffer of the current rendering context.

During rendering next object, before updating a pixel in color buffer, openGL will compare the distance of current pixel from view point with the z-value in z-buffer( depth buffer). OpenGL modifies color buffer and depth buffer only if z-value of current pixel is lower than the z value of corresponding location in z buffer. If the new pixel is close to the eye point, openGL places the new pixel’s color in color buffer and its depth buffer.

Installable Client Driver

Installable Client Driver

Hardware acceleration is achieved in OpenGL through ICD’s. ICD contain methods for high speed rendering( that is supported by hardware).

To increase performance, we bought new video hardware( GPU ). But openGL calls are then also routed through openGL32.dll. To achieve hardware capabilities hardware venders provides their openGL ICD’s, which are implemented by hardware vendors, and these functions are capable of calling high speed methods implemented in hardware. This way openGL32.dll achieves high speed rendering.

I think the communication between openGL32.dll and OpenGL display driver is performed through ICD and generic openGL driver. The software interface between hardware driver( display driver ) and openGL32.dll is capable of routing openGL calls to high speed methods that are implemented in hardware.

OpenGL starter

Hi,

I’m a new one to OpenGL programming. and I want publish my intersting studies in Opengl. This blog is started for studying OpenGl and publishing my study notes.

OpenGL starter