161 lines
5.8 KiB
HTML
161 lines
5.8 KiB
HTML
<!DOCTYPE html>
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta name="vsisbn" content="1576101746" />
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<meta name="vstitle" content="Michael Abrash's Graphics Programming Black Book, Special Edition" />
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<meta name="vsauthor" content="Michael Abrash" />
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<meta name="vspublisher" content="The Coriolis Group" />
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<meta name="vspubdate" content="07/01/97" />
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<meta name="vscategory" content="Web and Software Development: Game Development,Web and Software Development: Graphics and Multimedia Development" />
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<title>Michael Abrash's Graphics Programming Black Book Special Edition: Fast 3-D Animation: Meet X-Sharp</title>
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<meta name="chapter" content="52" />
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<meta name="pages" content="977-979" />
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</head>
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<body>
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<center>
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<table border="1">
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<tr>
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<td>
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<a href="52-03.html">Previous</a>
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</td>
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<td>
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<a href="index.html">Table of Contents</a>
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</td>
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<td>
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<a href="52-05.html">Next</a>
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</td>
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</tr>
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</table>
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</center>
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<p><b>LISTING 52.6 L52-6.C</b></p>
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<pre>
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/* Rotates and moves a polygon-based object around the three axes.
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Movement is implemented only along the Z axis currently. */
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#include “polygon.h”
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void RotateAndMovePObject(PObject * ObjectToMove)
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{
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if (--ObjectToMove->RDelayCount == 0) { /* rotate */
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ObjectToMove->RDelayCount = ObjectToMove->RDelayCountBase;
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if (ObjectToMove->Rotate.RotateX != 0.0)
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AppendRotationX(ObjectToMove->XformToWorld,
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ObjectToMove->Rotate.RotateX);
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if (ObjectToMove->Rotate.RotateY != 0.0)
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AppendRotationY(ObjectToMove->XformToWorld,
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ObjectToMove->Rotate.RotateY);
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if (ObjectToMove->Rotate.RotateZ != 0.0)
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AppendRotationZ(ObjectToMove->XformToWorld,
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ObjectToMove->Rotate.RotateZ);
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ObjectToMove->RecalcXform = 1;
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}
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/* Move in Z, checking for bouncing and stopping */
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if (--ObjectToMove->MDelayCount == 0) {
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ObjectToMove->MDelayCount = ObjectToMove->MDelayCountBase;
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ObjectToMove->XformToWorld[2][3] += ObjectToMove->Move.MoveZ;
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if (ObjectToMove->XformToWorld[2][3]>ObjectToMove->Move.MaxZ)
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ObjectToMove->Move.MoveZ = 0; /* stop if close enough */
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ObjectToMove->RecalcXform = 1;
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}
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}
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</pre>
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<p><b>LISTING 52.7 L52-7.C</b></p>
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<pre>
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/* Draws all visible faces in specified polygon-based object. Object must have
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previously been transformed and projected, so that ScreenVertexList array is
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filled in. */
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#include “polygon.h”
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void DrawPObject(PObject * ObjectToXform)
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{
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int i, j, NumFaces = ObjectToXform->NumFaces, NumVertices;
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int * VertNumsPtr;
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Face * FacePtr = ObjectToXform->FaceList;
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Point * ScreenPoints = ObjectToXform->ScreenVertexList;
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long v1, v2, w1, w2;
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Point Vertices[MAX_POLY_LENGTH];
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PointListHeader Polygon;
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/* Draw each visible face (polygon) of the object in turn */
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for (i=0; i<NumFaces; i++, FacePtr++) {
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NumVertices = FacePtr->NumVerts;
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/* Copy over the face's vertices from the vertex list */
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for (j=0, VertNumsPtr=FacePtr->VertNums; j<NumVertices; j++)
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Vertices[j] = ScreenPoints[*VertNumsPtr++];
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/* Draw only if outside face showing (if the normal to the
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polygon points toward viewer; that is, has a positive Z component) */
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v1 = Vertices[1].X - Vertices[0].X;
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w1 = Vertices[NumVertices-1].X - Vertices[0].X;
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v2 = Vertices[1].Y - Vertices[0].Y;
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w2 = Vertices[NumVertices-1].Y - Vertices[0].Y;
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if ((v1*w2 - v2*w1) > 0) {
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/* It is facing the screen, so draw */
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/* Appropriately adjust the extent of the rectangle used to
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erase this object later */
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for (j=0; j<NumVertices; j++) {
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if (Vertices[j].X >
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ObjectToXform->EraseRect[NonDisplayedPage].Right)
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if (Vertices[j].X < SCREEN_WIDTH)
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ObjectToXform->EraseRect[NonDisplayedPage].Right =
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Vertices[j].X;
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else ObjectToXform->EraseRect[NonDisplayedPage].Right =
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SCREEN_WIDTH;
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if (Vertices[j].Y >
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ObjectToXform->EraseRect[NonDisplayedPage].Bottom)
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if (Vertices[j].Y < SCREEN_HEIGHT)
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ObjectToXform->EraseRect[NonDisplayedPage].Bottom =
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Vertices[j].Y;
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else ObjectToXform->EraseRect[NonDisplayedPage].Bottom=
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SCREEN_HEIGHT;
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if (Vertices[j].X <
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ObjectToXform->EraseRect[NonDisplayedPage].Left)
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if (Vertices[j].X > 0)
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ObjectToXform->EraseRect[NonDisplayedPage].Left =
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Vertices[j].X;
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else ObjectToXform->EraseRect[NonDisplayedPage].Left=0;
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if (Vertices[j].Y <
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ObjectToXform->EraseRect[NonDisplayedPage].Top)
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if (Vertices[j].Y > 0)
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ObjectToXform->EraseRect[NonDisplayedPage].Top =
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Vertices[j].Y;
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else ObjectToXform->EraseRect[NonDisplayedPage].Top=0;
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}
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/* Draw the polygon */
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DRAW_POLYGON(Vertices, NumVertices, FacePtr->Color, 0, 0);
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}
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}
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}
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</pre>
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<center>
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<table border="1">
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<tr>
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<td>
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<a href="52-03.html">Previous</a>
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</td>
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<td>
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<a href="index.html">Table of Contents</a>
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</td>
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<td>
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<a href="52-05.html">Next</a>
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</td>
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</tr>
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</table>
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</center>
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<hr width="90%" size="1" noshade="noshade" />
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<div align="center">
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Graphics Programming Black Book © 2001 Michael Abrash
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</div>
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</body>
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</html>
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