HGE tutorial 04 学习笔记及摘录

Tutorial 04 - Rendering to texture

In this tutorial we will learn how to use render targets. 



First, we declare the variables to handle the render target and the sprite that we will associate with it:

hgeSprite*   tar;HTARGET      target;

During some events like video mode switching, the render target's texture handle may change. So, we write the GfxRestoreFunc function in which we obtain the new render target's texture:

bool GfxRestoreFunc(){  if(tar && target)       tar->SetTexture(hge->Target_GetTexture(target));  return false;}

In the RenderFunc we first render all our stuff onto the texture, specifying our render target in the Gfx_BeginScene call:

 
  hge->Gfx_BeginScene(target);  hge->Gfx_Clear(0);  par->Render();  spr->Render(x, y);  hge->Gfx_EndScene();

Then we render several instances of the texture to the screen:

  
  hge->Gfx_BeginScene();  hge->Gfx_Clear(0);  for(i=0;i<6;i++)  {    tar->SetColor(0xFFFFFF | (((5-i)*40+55)<<24));    tar->RenderEx(i*100.0f, i*50.0f, i*M_PI/8, 1.0f-i*0.1f);  }  fnt->printf(5, 5 ,HGETEXT_LEFT, "dt:%.3f\nFPS:%d",              hge->Timer_GetDelta(), hge->Timer_GetFPS());  hge->Gfx_EndScene();

In the WinMain function we attach our GfxRestoreFunc function:

  
hge->System_SetState(HGE_GFXRESTOREFUNC, GfxRestoreFunc);

Then, after HGE initiation, we create a render target and a sprite that we will use to make rendering of the created texture easier:

 
   target=hge->Target_Create(512,512,false);    tar=new hgeSprite(           hge->Target_GetTexture(target),0,0,512,512);    tar->SetBlendMode(           BLEND_COLORMUL | BLEND_ALPHAADD | BLEND_NOZWRITE);

During shutdown we delete the sprite that we used to render the generated texture and the render target itself:

   
 delete tar; hge->Target_Free(target);

The rest of shutdown process is identical to the one demonstrated in previous tutorials. 

The complete source code with detailed comments for this tutorial you may find in the folder tutorials\tutorial04. The required media files you'll find in the folder tutorials\precompiled.

源码及简单注释

/*** Haaf's Game Engine 1.8** Copyright (C) 2003-2007, Relish Games** hge.relishgames.com**** hge_tut04 - Using render targets*/// Copy the files "particles.png", "menu.wav",// "font1.fnt", "font1.png" and "trail.psi" from// the folder "precompiled" to the folder with// executable file. Also copy hge.dll and bass.dll// to the same folder.#include "..\..\include\hge.h"#include "..\..\include\hgesprite.h"#include "..\..\include\hgefont.h"#include "..\..\include\hgeparticle.h"HGE *hge=0;hgeSprite*spr;hgeSprite*spt;hgeSprite*tar;hgeFont*fnt;hgeParticleSystem*par;HTEXTUREtex;HEFFECTsnd;// HGE render target handleHTARGETtarget;float x=100.0f, y=100.0f;float dx=0.0f, dy=0.0f;const float speed=90;const float friction=0.98f;void boom() {int pan=int((x-256)/2.56f);float pitch=(dx*dx+dy*dy)*0.0005f+0.2f;hge->Effect_PlayEx(snd,100,pan,pitch);}// This function will be called by HGE when// render targets were lost and have been just created// again. We use it here to update the render// target's texture handle that changes during recreation.bool GfxRestoreFunc()//当窗口焦点失去再重新获得焦点时，会丢失场景数据，这里重新获得数据{if(tar && target) tar->SetTexture(hge->Target_GetTexture(target));return false;}bool FrameFunc(){float dt=hge->Timer_GetDelta();// Process keysif (hge->Input_GetKeyState(HGEK_ESCAPE)) return true;if (hge->Input_GetKeyState(HGEK_LEFT)) dx-=speed*dt;if (hge->Input_GetKeyState(HGEK_RIGHT)) dx+=speed*dt;if (hge->Input_GetKeyState(HGEK_UP)) dy-=speed*dt;if (hge->Input_GetKeyState(HGEK_DOWN)) dy+=speed*dt;// Do some movement calculations and collision detectiondx*=friction; dy*=friction; x+=dx; y+=dy;if(x>496) {x=496-(x-496);dx=-dx;boom();}if(x<16) {x=16+16-x;dx=-dx;boom();}if(y>496) {y=496-(y-496);dy=-dy;boom();}if(y<16) {y=16+16-y;dy=-dy;boom();}// Update particle systempar->info.nEmission=(int)(dx*dx+dy*dy);//速度越快，放射的粒子数越多par->MoveTo(x,y);//将粒子系统移到该位置par->Update(dt);//更新粒子系统return false;}bool RenderFunc(){int i;// Render graphics to the texturehge->Gfx_BeginScene(target);hge->Gfx_Clear(0);par->Render();spr->Render(x, y);hge->Gfx_EndScene();// Now put several instances of the rendered texture to the screenhge->Gfx_BeginScene();hge->Gfx_Clear(0);for(i=0;i<6;i++){tar->SetColor(0xFFFFFF | (((5-i)*40+55)<<24)); //颜色变化//参数3 旋转弧度 参数4 大小变化tar->RenderEx(i*100.0f, i*50.0f, i*M_PI/8,1.0f-i*0.06f);}fnt->printf(5, 5, HGETEXT_LEFT, "dt:%.3f\nFPS:%d (constant)", hge->Timer_GetDelta(), hge->Timer_GetFPS());hge->Gfx_EndScene();return false;}int WINAPI WinMain(HINSTANCE, HINSTANCE, LPSTR, int){hge = hgeCreate(HGE_VERSION);hge->System_SetState(HGE_LOGFILE, "hge_tut04.log");hge->System_SetState(HGE_FRAMEFUNC, FrameFunc);hge->System_SetState(HGE_RENDERFUNC, RenderFunc);hge->System_SetState(HGE_GFXRESTOREFUNC, GfxRestoreFunc);//??hge->System_SetState(HGE_TITLE, "HGE Tutorial 04 - Using render targets");hge->System_SetState(HGE_FPS, 100);hge->System_SetState(HGE_WINDOWED, true);hge->System_SetState(HGE_SCREENWIDTH, 800);hge->System_SetState(HGE_SCREENHEIGHT, 600);hge->System_SetState(HGE_SCREENBPP, 32);tar=0;target=0;if(hge->System_Initiate()) {snd=hge->Effect_Load("menu.wav");tex=hge->Texture_Load("particles.png");if(!snd || !tex){// If one of the data files is not found, display// an error message and shutdown.MessageBox(NULL, "Can't load one of the following files:\nMENU.WAV, PARTICLES.PNG, FONT1.FNT, FONT1.PNG, TRAIL.PSI", "Error", MB_OK | MB_ICONERROR | MB_APPLMODAL);hge->System_Shutdown();hge->Release();return 0;}//hgeSprite(tex,x,y,w,h) 纹理x,y坐标  w,h 精灵宽，高，不同的坐标能调整出不同的精灵图案spr=new hgeSprite(tex, 96, 64, 32, 32);//纹理精灵spr->SetColor(0xFFFFA000);//设置精灵锚点,锚点是缩放，旋转和运转位置的中心，精灵出现的位置，相对与精灵方块（16，16）为中心//（0，0）为左上角spr->SetHotSpot(16,16);fnt=new hgeFont("font1.fnt");spt=new hgeSprite(tex, 64, 64, 32, 32); //粒子精灵spt->SetBlendMode(BLEND_COLORMUL | BLEND_ALPHAADD | BLEND_NOZWRITE);spt->SetHotSpot(16,16);par=new hgeParticleSystem("trail.psi",spt);//加载粒子系统par->Fire();// Create a render target and a sprite for ittarget=hge->Target_Create(512,512,false);tar=new hgeSprite(hge->Target_GetTexture(target),0,0,512,512);tar->SetBlendMode(BLEND_COLORMUL | BLEND_ALPHAADD | BLEND_NOZWRITE);// Let's rock now!hge->System_Start();// Delete created objects and free loaded resourcesdelete par;delete fnt;delete spt;delete spr;delete tar;hge->Target_Free(target);hge->Texture_Free(tex);hge->Effect_Free(snd);}// Clean up and shutdownhge->System_Shutdown();hge->Release();return 0;}