Animation with Transforms
We can apply this functionality to animation as well. Since D3DXSprite is used to draw single- or multi-frame sprites, you can use the same transformation to rotate and scale a sprite regardless of whether it’s animated. Figure 4.5 shows a sprite sheet containing frames from an animated space rock or asteroid.
This program uses the same transforms that were applied to the fatship sprite in the previous example; the difference now is that we’re dealing with an animated sprite. What’s the difference? As far as Direct3D is concerned, there is none. Our Sprite::draw() method handles single “static” sprites as well as sprites with animation.
Let’s give animation with rotation and scaling a try. Figure 4.6 shows the output from the RotateAnimDemo program, with the code listing to follow.
Figure 4.6. The RotateAnimDemo program draws an animated sprite with rotation and scaling.
#include "..EngineAdvanced2D.h"
using namespace Advanced2D;
Sprite *asteroid;
bool game_preload()
{
g_engine->setAppTitle("SPRITE ANIMATE/ROTATE/SCALE DEMO");
g_engine->setFullscreen(false);
g_engine->setScreenWidth(800);
g_engine->setScreenHeight(600);
g_engine->setColorDepth(32);
return true;
}
bool game_init(HWND)
{
//load sprite
asteroid = new Sprite();
asteroid->loadImage("asteroid.tga");
asteroid->setTotalFrames(64);
asteroid->setColumns(8);
asteroid->setSize(60,60);
asteroid->setFrameTimer(30);
return true;
}
void game_update()
{
static float scale = 0.005f;
float r,s;
//set position
asteroid->setPosition(400,300);
//set rotation
asteroid->setRotation(timeGetTime()/600.0f);
//set scale
s = asteroid->getScale() + scale;
if (s < 0.25 || s > 5.0f) scale *= -1;
asteroid->setScale(s);
//exit when escape key is pressed
if (KEY_DOWN(VK_ESCAPE)) g_engine->Close();
}
void game_end()
{
delete asteroid;
}
void game_render3d()
{
g_engine->ClearScene(D3DCOLOR_XRGB(0,0,80));
}
void game_render2d()
{
asteroid->animate();
asteroid->draw();
}