示例#1
0
void DrawGLScene()									// Main Drawing Routine
{
  GLmatrix16f Minv, Inv;
  GLvector4f  lp;

  // Clear Color Buffer, Depth Buffer, Stencil Buffer
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
  glColor4f(0.7f, 0.4f, 0.0f, 1.0f);
  glLoadIdentity();

  glPushMatrix(); {
      glTranslatef(0.0f, 0.0f, -20.0f);					// Zoom Into Screen 20 Units
      glLightfv(GL_LIGHT1, GL_POSITION, LightPos);		// Position Light1
      glTranslatef(SpherePos[0], SpherePos[1], SpherePos[2]);	// Position The Sphere
      gluSphere(q, 1.5f, 32, 16);							// Draw A Sphere
  } glPopMatrix();

  glPushMatrix(); {
      glTranslatef(0.0f, 0.0f, -20.0f);					// Zoom Into The Screen 20 Units
      DrawGLRoom();										// Draw The Room
      glTranslatef(ObjPos[0], ObjPos[1], ObjPos[2]);		// Position The Object
      glRotatef(xrot, 1.0f, 0.0f, 0.0f);					// Spin It On The X Axis By xrot
      glRotatef(yrot, 0.0f, 1.0f, 0.0f);					// Spin It On The Y Axis By yrot
      DrawGLObject(obj);									// Procedure For Drawing The Loaded Object

      // 获得光源的位置(返回值是在视觉坐标系下的)
      glGetLightfv(GL_LIGHT1, GL_POSITION, lp);
      glGetFloatv(GL_MODELVIEW_MATRIX, Minv);
      m3dInvertMatrix44(Inv, Minv);
      // 把光源位置从视觉坐标系下变换到当前的场景坐标系(obj)下.
      VMatMult(Inv, lp);
      // 开始渲染阴影
      CastShadow(&obj, lp);

      // 用一个小黄球标记出光源的位置
      glPushMatrix(); {
          glColor4f(0.7f, 0.4f, 0.0f, 1.0f);					// Set Color To Purplish Blue
          glDisable(GL_LIGHTING);								// Disable Lighting
          glDepthMask(GL_FALSE);								// Disable Depth Mask
          glTranslatef(lp[0], lp[1], lp[2]);
          gluSphere(q, 0.2f, 16, 8);
          glEnable(GL_LIGHTING);								// Enable Lighting
          glDepthMask(GL_TRUE);								// Enable Depth Mask
      } glPopMatrix();
  } glPopMatrix();

  xrot += xspeed;	
  yrot += yspeed;	

  glFlush();
  glutSwapBuffers();
}
示例#2
0
int DrawGLScene(GLvoid)									// Main Drawing Routine
{
	GLmatrix16f Minv;
	GLvector4f wlp, lp;

	// Clear Color Buffer, Depth Buffer, Stencil Buffer
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
	
	glLoadIdentity();									// Reset Modelview Matrix
	glTranslatef(0.0f, 0.0f, -20.0f);					// Zoom Into Screen 20 Units
	glLightfv(GL_LIGHT1, GL_POSITION, LightPos);		// Position Light1
	glTranslatef(SpherePos[0], SpherePos[1], SpherePos[2]);	// Position The Sphere
	gluSphere(q, 1.5f, 32, 16);							// Draw A Sphere

	// calculate light's position relative to local coordinate system
	// dunno if this is the best way to do it, but it actually works
	// if u find another aproach, let me know ;)

	// we build the inversed matrix by doing all the actions in reverse order
	// and with reverse parameters (notice -xrot, -yrot, -ObjPos[], etc.)
	glLoadIdentity();									// Reset Matrix
	glRotatef(-yrot, 0.0f, 1.0f, 0.0f);					// Rotate By -yrot On Y Axis
	glRotatef(-xrot, 1.0f, 0.0f, 0.0f);					// Rotate By -xrot On X Axis
	glGetFloatv(GL_MODELVIEW_MATRIX,Minv);				// Retrieve ModelView Matrix (Stores In Minv)
	lp[0] = LightPos[0];								// Store Light Position X In lp[0]
	lp[1] = LightPos[1];								// Store Light Position Y In lp[1]
	lp[2] = LightPos[2];								// Store Light Position Z In lp[2]
	lp[3] = LightPos[3];								// Store Light Direction In lp[3]
	VMatMult(Minv, lp);									// We Store Rotated Light Vector In 'lp' Array
	glTranslatef(-ObjPos[0], -ObjPos[1], -ObjPos[2]);	// Move Negative On All Axis Based On ObjPos[] Values (X, Y, Z)
	glGetFloatv(GL_MODELVIEW_MATRIX,Minv);				// Retrieve ModelView Matrix From Minv
	wlp[0] = 0.0f;										// World Local Coord X To 0
	wlp[1] = 0.0f;										// World Local Coord Y To 0
	wlp[2] = 0.0f;										// World Local Coord Z To 0
	wlp[3] = 1.0f;
	VMatMult(Minv, wlp);								// We Store The Position Of The World Origin Relative To The
														// Local Coord. System In 'wlp' Array
	lp[0] += wlp[0];									// Adding These Two Gives Us The
	lp[1] += wlp[1];									// Position Of The Light Relative To
	lp[2] += wlp[2];									// The Local Coordinate System

	glColor4f(0.7f, 0.4f, 0.0f, 1.0f);					// Set Color To An Orange
	glLoadIdentity();									// Reset Modelview Matrix
	glTranslatef(0.0f, 0.0f, -20.0f);					// Zoom Into The Screen 20 Units
	DrawGLRoom();										// Draw The Room
	glTranslatef(ObjPos[0], ObjPos[1], ObjPos[2]);		// Position The Object
	glRotatef(xrot, 1.0f, 0.0f, 0.0f);					// Spin It On The X Axis By xrot
	glRotatef(yrot, 0.0f, 1.0f, 0.0f);					// Spin It On The Y Axis By yrot
	DrawGLObject(obj);									// Procedure For Drawing The Loaded Object
	CastShadow(&obj, lp);								// Procedure For Casting The Shadow Based On The Silhouette

	glColor4f(0.7f, 0.4f, 0.0f, 1.0f);					// Set Color To Purplish Blue
	glDisable(GL_LIGHTING);								// Disable Lighting
	glDepthMask(GL_FALSE);								// Disable Depth Mask
	glTranslatef(lp[0], lp[1], lp[2]);					// Translate To Light's Position
														// Notice We're Still In Local Coordinate System
	gluSphere(q, 0.2f, 16, 8);							// Draw A Little Yellow Sphere (Represents Light)
	glEnable(GL_LIGHTING);								// Enable Lighting
	glDepthMask(GL_TRUE);								// Enable Depth Mask

	xrot += xspeed;										// Increase xrot By xspeed
	yrot += yspeed;										// Increase yrot By yspeed

	glFlush();											// Flush The OpenGL Pipeline
	return TRUE;										// Everything Went OK
}