| The GrVertex Structure |
The GrVertex structure, first presented in Chapter 2, collects together all the parameters that define a vertex.
In this chapter, only the x and y co-ordinates will be discussed;
the other parameters are called into play in later chapters.
| typedef struct {
float x, y, z; /* x, y, z of screen space. z is ignored */ float ooz; /* 65535/z (used for z buffering) */ float oow; /* 1/w (used for w buffering) */ float r, g, b, a; /* red, green, blue, and alpha ([0..255.0]) */ GrTmuVertex tmuvtx[GLIDE_NUM_TMU]; } GrVertex; |
The x and y co-ordinates are 32-bit floating point values that represent the position of the vertex in screen space. While the Voodoo Graphics hardware renders only triangles, Glide provides functions to draw points, lines, and polygons as well as triangles .When a point, line, triangle, or polygon is rendered, its appearance will reflect the current state of the rendering pipeline. That is, if texture mapping is enabled, then the point, line, triangle, or polygon will be texture mapped. Similarly, alpha blending, fogging, color, and lighting effects, chroma-keying, and other special effects will contribute to the appearance of any and all geometric shapes drawn while they are enabled.