Use backtick code blocks for syntax highlighting
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James Gregory
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203 changed files with 26546 additions and 25801 deletions
224
52-02.md
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52-02.md
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@ -12,123 +12,127 @@ pages: 973-974
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**LISTING 52.1 L52-1.C**
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/* 3-D animation program to rotate 12 cubes. Uses fixed point. All C code
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tested with Borland C++ in C compilation mode and the small model. */
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```c
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/* 3-D animation program to rotate 12 cubes. Uses fixed point. All C code
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tested with Borland C++ in C compilation mode and the small model. */
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#include <conio.h>
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#include <dos.h>
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#include "polygon.h"
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#include <conio.h>
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#include <dos.h>
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#include "polygon.h"
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/* base offset of page to which to draw */
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unsigned int CurrentPageBase = 0;
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/* clip rectangle; clips to the screen */
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int ClipMinX = 0, ClipMinY = 0;
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int ClipMaxX = SCREEN_WIDTH, ClipMaxY = SCREEN_HEIGHT;
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static unsigned int PageStartOffsets[2] =
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{PAGE0_START_OFFSET,PAGE1_START_OFFSET};
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int DisplayedPage, NonDisplayedPage;
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int RecalcAllXforms = 1, NumObjects = 0;
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Xform WorldViewXform; /* initialized from floats */
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/* pointers to objects */
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Object *ObjectList[MAX_OBJECTS];
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/* base offset of page to which to draw */
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unsigned int CurrentPageBase = 0;
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/* clip rectangle; clips to the screen */
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int ClipMinX = 0, ClipMinY = 0;
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int ClipMaxX = SCREEN_WIDTH, ClipMaxY = SCREEN_HEIGHT;
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static unsigned int PageStartOffsets[2] =
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{PAGE0_START_OFFSET,PAGE1_START_OFFSET};
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int DisplayedPage, NonDisplayedPage;
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int RecalcAllXforms = 1, NumObjects = 0;
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Xform WorldViewXform; /* initialized from floats */
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/* pointers to objects */
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Object *ObjectList[MAX_OBJECTS];
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void main() {
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int Done = 0, i;
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Object *ObjectPtr;
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union REGS regset;
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void main() {
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int Done = 0, i;
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Object *ObjectPtr;
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union REGS regset;
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InitializeFixedPoint(); /* set up fixed-point data */
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InitializeCubes(); /* set up cubes and add them to object list; other
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objects would be initialized now, if there were any */
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Set320x240Mode(); /* set the screen to mode X */
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ShowPage(PageStartOffsets[DisplayedPage = 0]);
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/* Keep transforming the cube, drawing it to the undisplayed page,
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and flipping the page to show it */
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do {
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/* For each object, regenerate viewing info, if necessary */
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for (i=0; i<NumObjects; i++) {
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if ((ObjectPtr = ObjectList[i])->RecalcXform ||
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RecalcAllXforms) {
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ObjectPtr->RecalcFunc(ObjectPtr);
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ObjectPtr->RecalcXform = 0;
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}
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}
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RecalcAllXforms = 0;
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CurrentPageBase = /* select other page for drawing to */
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PageStartOffsets[NonDisplayedPage = DisplayedPage ^ 1];
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/* For each object, clear the portion of the non-displayed page
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that was drawn to last time, then reset the erase extent */
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for (i=0; i<NumObjects; i++) {
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ObjectPtr = ObjectList[i];
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FillRectangleX(ObjectPtr->EraseRect[NonDisplayedPage].Left,
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ObjectPtr->EraseRect[NonDisplayedPage].Top,
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ObjectPtr->EraseRect[NonDisplayedPage].Right,
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ObjectPtr->EraseRect[NonDisplayedPage].Bottom,
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CurrentPageBase, 0);
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ObjectPtr->EraseRect[NonDisplayedPage].Left =
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ObjectPtr->EraseRect[NonDisplayedPage].Top = 0x7FFF;
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ObjectPtr->EraseRect[NonDisplayedPage].Right =
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ObjectPtr->EraseRect[NonDisplayedPage].Bottom = 0;
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}
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/* Draw all objects */
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for (i=0; i<NumObjects; i++)
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ObjectList[i]->DrawFunc(ObjectList[i]);
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/* Flip to display the page into which we just drew */
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ShowPage(PageStartOffsets[DisplayedPage = NonDisplayedPage]);
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/* Move and reorient each object */
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for (i=0; i<NumObjects; i++)
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ObjectList[i]->MoveFunc(ObjectList[i]);
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if (kbhit())
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if (getch() == 0x1B) Done = 1; /* Esc to exit */
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} while (!Done);
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/* Return to text mode and exit */
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regset.x.ax = 0x0003; /* AL = 3 selects 80x25 text mode */
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int86(0x10, ®set, ®set);
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exit(1);
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}
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InitializeFixedPoint(); /* set up fixed-point data */
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InitializeCubes(); /* set up cubes and add them to object list; other
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objects would be initialized now, if there were any */
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Set320x240Mode(); /* set the screen to mode X */
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ShowPage(PageStartOffsets[DisplayedPage = 0]);
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/* Keep transforming the cube, drawing it to the undisplayed page,
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and flipping the page to show it */
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do {
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/* For each object, regenerate viewing info, if necessary */
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for (i=0; i<NumObjects; i++) {
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if ((ObjectPtr = ObjectList[i])->RecalcXform ||
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RecalcAllXforms) {
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ObjectPtr->RecalcFunc(ObjectPtr);
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ObjectPtr->RecalcXform = 0;
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}
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}
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RecalcAllXforms = 0;
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CurrentPageBase = /* select other page for drawing to */
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PageStartOffsets[NonDisplayedPage = DisplayedPage ^ 1];
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/* For each object, clear the portion of the non-displayed page
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that was drawn to last time, then reset the erase extent */
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for (i=0; i<NumObjects; i++) {
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ObjectPtr = ObjectList[i];
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FillRectangleX(ObjectPtr->EraseRect[NonDisplayedPage].Left,
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ObjectPtr->EraseRect[NonDisplayedPage].Top,
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ObjectPtr->EraseRect[NonDisplayedPage].Right,
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ObjectPtr->EraseRect[NonDisplayedPage].Bottom,
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CurrentPageBase, 0);
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ObjectPtr->EraseRect[NonDisplayedPage].Left =
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ObjectPtr->EraseRect[NonDisplayedPage].Top = 0x7FFF;
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ObjectPtr->EraseRect[NonDisplayedPage].Right =
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ObjectPtr->EraseRect[NonDisplayedPage].Bottom = 0;
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}
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/* Draw all objects */
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for (i=0; i<NumObjects; i++)
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ObjectList[i]->DrawFunc(ObjectList[i]);
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/* Flip to display the page into which we just drew */
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ShowPage(PageStartOffsets[DisplayedPage = NonDisplayedPage]);
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/* Move and reorient each object */
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for (i=0; i<NumObjects; i++)
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ObjectList[i]->MoveFunc(ObjectList[i]);
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if (kbhit())
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if (getch() == 0x1B) Done = 1; /* Esc to exit */
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} while (!Done);
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/* Return to text mode and exit */
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regset.x.ax = 0x0003; /* AL = 3 selects 80x25 text mode */
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int86(0x10, ®set, ®set);
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exit(1);
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}
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```
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**LISTING 52.2 L52-2.C**
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/* Transforms all vertices in the specified polygon-based object into view
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space, then perspective projects them to screen space and maps them to screen
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coordinates, storing results in the object. Recalculates object->view
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transformation because only if transform changes would we bother
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to retransform the vertices. */
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```c
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/* Transforms all vertices in the specified polygon-based object into view
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space, then perspective projects them to screen space and maps them to screen
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coordinates, storing results in the object. Recalculates object->view
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transformation because only if transform changes would we bother
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to retransform the vertices. */
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#include <math.h>
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#include "polygon.h"
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#include <math.h>
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#include "polygon.h"
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void XformAndProjectPObject(PObject * ObjectToXform)
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{
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int i, NumPoints = ObjectToXform->NumVerts;
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Point3 * Points = ObjectToXform->VertexList;
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Point3 * XformedPoints = ObjectToXform->XformedVertexList;
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Point3 * ProjectedPoints = ObjectToXform->ProjectedVertexList;
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Point * ScreenPoints = ObjectToXform->ScreenVertexList;
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void XformAndProjectPObject(PObject * ObjectToXform)
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{
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int i, NumPoints = ObjectToXform->NumVerts;
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Point3 * Points = ObjectToXform->VertexList;
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Point3 * XformedPoints = ObjectToXform->XformedVertexList;
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Point3 * ProjectedPoints = ObjectToXform->ProjectedVertexList;
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Point * ScreenPoints = ObjectToXform->ScreenVertexList;
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/* Recalculate the object->view transform */
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ConcatXforms(WorldViewXform, ObjectToXform->XformToWorld,
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ObjectToXform->XformToView);
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/* Apply that new transformation and project the points */
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for (i=0; i<NumPoints; i++, Points++, XformedPoints++,
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ProjectedPoints++, ScreenPoints++) {
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/* Transform to view space */
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XformVec(ObjectToXform->XformToView, (Fixedpoint *) Points,
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(Fixedpoint *) XformedPoints);
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/* Perspective-project to screen space */
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ProjectedPoints->X =
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FixedMul(FixedDiv(XformedPoints->X, XformedPoints->Z),
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DOUBLE_TO_FIXED(PROJECTION_RATIO * (SCREEN_WIDTH/2)));
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ProjectedPoints->Y =
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FixedMul(FixedDiv(XformedPoints->Y, XformedPoints->Z),
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DOUBLE_TO_FIXED(PROJECTION_RATIO * (SCREEN_WIDTH/2)));
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ProjectedPoints->Z = XformedPoints->Z;
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/* Convert to screen coordinates. The Y coord is negated to flip from
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increasing Y being up to increasing Y being down, as expected by polygon
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filler. Add in half the screen width and height to center on screen. */
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ScreenPoints->X = ((int) ((ProjectedPoints->X +
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DOUBLE_TO_FIXED(0.5)) >> 16)) + SCREEN_WIDTH/2;
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ScreenPoints->Y = (-((int) ((ProjectedPoints->Y +
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DOUBLE_TO_FIXED(0.5)) >> 16))) + SCREEN_HEIGHT/2;
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}
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}
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/* Recalculate the object->view transform */
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ConcatXforms(WorldViewXform, ObjectToXform->XformToWorld,
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ObjectToXform->XformToView);
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/* Apply that new transformation and project the points */
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for (i=0; i<NumPoints; i++, Points++, XformedPoints++,
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ProjectedPoints++, ScreenPoints++) {
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/* Transform to view space */
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XformVec(ObjectToXform->XformToView, (Fixedpoint *) Points,
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(Fixedpoint *) XformedPoints);
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/* Perspective-project to screen space */
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ProjectedPoints->X =
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FixedMul(FixedDiv(XformedPoints->X, XformedPoints->Z),
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DOUBLE_TO_FIXED(PROJECTION_RATIO * (SCREEN_WIDTH/2)));
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ProjectedPoints->Y =
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FixedMul(FixedDiv(XformedPoints->Y, XformedPoints->Z),
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DOUBLE_TO_FIXED(PROJECTION_RATIO * (SCREEN_WIDTH/2)));
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ProjectedPoints->Z = XformedPoints->Z;
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/* Convert to screen coordinates. The Y coord is negated to flip from
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increasing Y being up to increasing Y being down, as expected by polygon
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filler. Add in half the screen width and height to center on screen. */
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ScreenPoints->X = ((int) ((ProjectedPoints->X +
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DOUBLE_TO_FIXED(0.5)) >> 16)) + SCREEN_WIDTH/2;
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ScreenPoints->Y = (-((int) ((ProjectedPoints->Y +
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DOUBLE_TO_FIXED(0.5)) >> 16))) + SCREEN_HEIGHT/2;
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}
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}
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```
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