inline void __track_move(GutMouseInfo mouse)
{
int px, py, buttonState[3];
GutGetMouseState(px, py, buttonState);
m_fTouchX = (px / (m_iCanvasWidth / 2.0)) - 0.98;
m_fTouchY = (-1 * (py / (m_iCanvasHeight / 2.0))) + 0.95;
}
// `使用OpenGL來繪圖`
void RenderFrameOpenGL(void)
{
// `取得視窗大小`
int w, h;
GutGetWindowSize(w, h);
// `清除畫面`
glClearColor(0.4f, 0.4f, 0.4f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// `在螢幕上畫出行星運動`
RenderSolarSystemOpenGL(false);
/*
`啟動Selection Buffer, 硬體會試著去重畫一次3D物件,`
`但不會更新畫面, 只會記錄下落在畫面中某個范圍內所有3D物件.`
*/
int x,y,buttons[3];
GutGetMouseState(x, y, buttons);
if ( buttons[0] )
{
GLint viewport[4];
glSelectBuffer(BUFSIZE,selectBuf);
glRenderMode(GL_SELECT);
glInitNames();
glGetIntegerv(GL_VIEWPORT,viewport);
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
// `設定Selection Buffer的檢查范圍`
gluPickMatrix(x, viewport[3]-y, 3, 3, viewport);
float fRatio = (viewport[2]+0.0) / viewport[3];
glMultMatrixf( (float *)&g_projection_matrix );
// `在Selection Buffer中畫出3D物件`
RenderSolarSystemOpenGL(true);
int hits = glRenderMode(GL_RENDER);
GLuint *ptr = selectBuf;
GLuint Zmin = 0xffffffff;
GLuint SelectedObject = 0;
// `找出檢查范圍中, 距離鏡頭最近的物體.`
for ( int i=0; i<hits; i++, ptr+=4 )
{
if ( ptr[1] < Zmin )
{
Zmin = ptr[1];
SelectedObject = ptr[3];
}
}
switch(SelectedObject)
{
default:
case 0:
printf("Nothing\r");
break;
case 1:
printf("Sun \r");
break;
case 2:
printf("Earth \r");
break;
}
glMatrixMode(GL_PROJECTION);
glPopMatrix();
}
// `把背景backbuffer的畫面呈現出來`
GutSwapBuffersOpenGL();
}
