/*--------------------------------------------------------------------------------- Demonstrates how to use 3D picking on the DS Author: Gabe Ghearing Created: Feb 2007 This file is released into the public domain Basic idea behind picking; Draw the scene a second time with a projection matrix that only renders what is directly below the cursor. The GPU keeps track of how many polygons are drawn, so if a polygon is drawn in this limited view the polygon is directly below the cursor. Several polygons may be drawn under the cursor, so a position test is used for each object(a collection of polygons) to tell which object is closest to the camera. The object that is closest to the camera and under the cursor is the one that the user is clicking on. There are several optimizations that are not done in this example, such as: - Simplify models during the picking pass, the model needs to occupy the same area, but can usually use fewer polygons. - Save the projection matrix with glGetFixed() instead of recreating it every pass. *--------------------------------------------------------------------------------*/ #include <nds.h> #include <nds/arm9/postest.h> #include "cone_bin.h" #include "cylinder_bin.h" #include "sphere_bin.h" typedef enum { NOTHING, CONE, CYLINDER, SPHERE } Clickable; Clickable clicked; // what is being clicked int closeW; // closest distace to camera int polyCount; // keeps track of the number of polygons drawn // run before starting to draw an object while picking void startCheck() { while(PosTestBusy()); // wait for the position test to finish while(GFX_BUSY); // wait for all the polygons from the last object to be drawn PosTest_Asynch(0,0,0); // start a position test at the current translated position polyCount = GFX_POLYGON_RAM_USAGE; // save the polygon count } // run afer drawing an object while picking void endCheck(Clickable obj) { while(GFX_BUSY); // wait for all the polygons to get drawn while(PosTestBusy()); // wait for the position test to finish if(GFX_POLYGON_RAM_USAGE>polyCount) // if a polygon was drawn { if(PosTestWresult()<=closeW) { // this is currently the closest object under the cursor! closeW=PosTestWresult(); clicked=obj; } } } int main() { // initialize gl glInit(); u32 rotateX = 0; u32 rotateY = 0; //set mode 0, enable BG0 and set it to 3D videoSetMode(MODE_0_3D); // used to hold touched position touchPosition touchXY; lcdMainOnBottom(); // we are going to be touching the 3D display // enable edge outlining, this will be used to show which object is selected glEnable(GL_OUTLINE); //set the first outline color to white glSetOutlineColor(0,RGB15(31,31,31)); int viewport[]={0,0,255,191}; // used later for gluPickMatrix() // setup the rear plane glClearColor(0,0,0,0); // set BG to black and clear glClearPolyID(0); // the BG and polygons will have the same ID unless a polygon is highlighted glClearDepth(0x7FFF); // setup the camera gluLookAt( 0.0, 0.0, 1.0, //camera possition 0.0, 0.0, 0.0, //look at 0.0, 1.0, 0.0); //up glLight(0, RGB15(31,31,31) , 0, floattov10(-1.0), 0); // setup the light while(1) { // handle key input scanKeys(); u16 keys = keysHeld(); if(!(keys & KEY_UP)) rotateX += 3; if(!(keys & KEY_DOWN)) rotateX -= 3; if(!(keys & KEY_LEFT)) rotateY += 3; if(!(keys & KEY_RIGHT)) rotateY -= 3; // get touchscreen position touchRead(&touchXY); glViewport(0,0,255,191); // set the viewport to fullscreen // setup the projection matrix for regular drawing glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(60, 256.0 / 192.0, 0.1, 20); glMatrixMode(GL_MODELVIEW); // use the modelview matrix while drawing glPushMatrix(); // save the state of the current matrix(the modelview matrix) { glTranslatef32(0,0,floattof32(-6)); glRotateXi(rotateX); // add X rotation to the modelview matrix glRotateYi(rotateY); // add Y rotation to the modelview matrix glPushMatrix(); // save the state of the modelview matrix while making the first pass { // draw the scene for displaying glTranslatef32(floattof32(2.9),floattof32(0),floattof32(0)); // translate the modelview matrix to the drawing location if(clicked==CONE) { glPolyFmt(POLY_ALPHA(31) | POLY_CULL_BACK | POLY_FORMAT_LIGHT0 | POLY_ID(1)); // set a poly ID for outlining } else { glPolyFmt(POLY_ALPHA(31) | POLY_CULL_BACK | POLY_FORMAT_LIGHT0 | POLY_ID(0)); // set a poly ID for no outlining (same as BG) } glCallList((u32*)cone_bin); // draw a green cone from a predefined packed command list glTranslatef32(floattof32(-3),floattof32(1.8),floattof32(2)); // translate the modelview matrix to the drawing location if(clicked==CYLINDER) { glPolyFmt(POLY_ALPHA(31) | POLY_CULL_BACK | POLY_FORMAT_LIGHT0 | POLY_ID(1)); // set a poly ID for outlining } else { glPolyFmt(POLY_ALPHA(31) | POLY_CULL_BACK | POLY_FORMAT_LIGHT0 | POLY_ID(0)); // set a poly ID for no outlining (same as BG) } glCallList((u32*)cylinder_bin); // draw a blue cylinder from a predefined packed command list glTranslatef32(floattof32(.5),floattof32(-2.6),floattof32(-4)); // translate the modelview matrix to the drawing location if(clicked==SPHERE) { glPolyFmt(POLY_ALPHA(31) | POLY_CULL_BACK | POLY_FORMAT_LIGHT0 | POLY_ID(1)); // set a poly ID for outlining } else { glPolyFmt(POLY_ALPHA(31) | POLY_CULL_BACK | POLY_FORMAT_LIGHT0 | POLY_ID(0)); // set a poly ID for no outlining (same as BG) } glCallList((u32*)sphere_bin); // draw a red sphere from a predefined packed command list } glPopMatrix(1); // restores the modelview matrix to where it was just rotated // draw the scene again for picking { clicked = NOTHING; //reset what was clicked on closeW = 0x7FFFFFFF; //reset the distance //set the viewport to just off-screen, this hides all rendering that will be done during picking glViewport(0,192,0,192); // setup the projection matrix for picking glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPickMatrix((touchXY.px),(191-touchXY.py),4,4,viewport); // render only what is below the cursor gluPerspective(60, 256.0 / 192.0, 0.1, 20); // this must be the same as the original perspective matrix glMatrixMode(GL_MODELVIEW); // switch back to modifying the modelview matrix for drawing glTranslatef32(floattof32(2.9),floattof32(0),floattof32(0)); // translate the modelview matrix to the drawing location startCheck(); glCallList((u32*)cone_bin); // draw a cone from a predefined packed command list endCheck(CONE); glTranslatef32(floattof32(-3),floattof32(1.8),floattof32(2)); // translate the modelview matrix to the drawing location startCheck(); glCallList((u32*)cylinder_bin); // draw a cylinder from a predefined packed command list endCheck(CYLINDER); glTranslatef32(floattof32(.5),floattof32(-2.6),floattof32(-4)); // translate the modelview matrix to the drawing location startCheck(); glCallList((u32*)sphere_bin); // draw a sphere from a predefined packed command list endCheck(SPHERE); } } glPopMatrix(1); // restores the modelview matrix to its original state glFlush(0); // wait for everything to be drawn before starting on the next frame } return 0; }//end main
1.6.3
