在做游戏时遇到需要使用纯白色高亮精灵的场合,尝试了很多办法没有解决问题,目前有以下几种解法:
1. 最简单当然是切换成和精灵图片一样的另一张纯白图片。
2. 使用glTexEnvi。具体如下:
2.1 重写一个类继承CCSprite
2.2 改写draw 函数如下 :
void YourSprite::setHightlight(bool hightlight)
{
if (m_hightlight != hightlight)
{
m_hightlight = hightlight;
if (m_hightlight)
{
ccBlendFunc blendFunc = {GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA};
setBlendFunc(blendFunc);
}
else
{
ccBlendFunc blendFunc = {CC_BLEND_SRC, CC_BLEND_DST};
setBlendFunc(blendFunc);
}
}
}
void YourSprite::draw()
{
CCNode::draw();
CCAssert(! m_bUsesBatchNode, "");
// Default GL states: GL_TEXTURE_2D, GL_VERTEX_ARRAY, GL_COLOR_ARRAY, GL_TEXTURE_COORD_ARRAY
// Needed states: GL_TEXTURE_2D, GL_VERTEX_ARRAY, GL_COLOR_ARRAY, GL_TEXTURE_COORD_ARRAY
// Unneeded states: -
bool newBlend = m_sBlendFunc.src != CC_BLEND_SRC || m_sBlendFunc.dst != CC_BLEND_DST;
if (newBlend)
{
glBlendFunc(m_sBlendFunc.src, m_sBlendFunc.dst);
}
#define kQuadSize sizeof(m_sQuad.bl)
if (m_pobTexture)
{
glBindTexture(GL_TEXTURE_2D, m_pobTexture->getName());
}
else
{
glBindTexture(GL_TEXTURE_2D, 0);
}
if (m_hightlight)
{
glActiveTexture( GL_TEXTURE0 );
//the magic
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_ADD); //you can change me... GL_REPLACE, GL_SUBSTRACT produce nice effects
glTexEnvi(GL_TEXTURE_ENV, GL_SRC0_RGB, GL_PREVIOUS); //setColor
glTexEnvi(GL_TEXTURE_ENV, GL_SRC1_RGB, GL_TEXTURE); //your texture
}
long offset = (long)&m_sQuad;
// vertex
int diff = offsetof(ccV3F_C4B_T2F, vertices);
glVertexPointer(3, GL_FLOAT, kQuadSize, (void*)(offset + diff));
// color
diff = offsetof( ccV3F_C4B_T2F, colors);
glColorPointer(4, GL_UNSIGNED_BYTE, kQuadSize, (void*)(offset + diff));
// tex coords
diff = offsetof( ccV3F_C4B_T2F, texCoords);
glTexCoordPointer(2, GL_FLOAT, kQuadSize, (void*)(offset + diff));
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
if( newBlend )
{
glBlendFunc(CC_BLEND_SRC, CC_BLEND_DST);
}
#if CC_SPRITE_DEBUG_DRAW == 1
// draw bounding box
CCSize s = m_tContentSize;
CCPoint vertices[4] = {
ccp(0,0), ccp(s.width,0),
ccp(s.width,s.height), ccp(0,s.height)
};
ccDrawPoly(vertices, 4, true);
#elif CC_SPRITE_DEBUG_DRAW == 2
// draw texture box
const CCSize& s = m_obRect.size;
const CCPoint& offsetPix = getOffsetPositionInPixels();
CCPoint vertices[4] = {
ccp(offsetPix.x,offsetPix.y), ccp(offsetPix.x+s.width,offsetPix.y),
ccp(offsetPix.x+s.width,offsetPix.y+s.height), ccp(offsetPix.x,offsetPix.y+s.height)
};
ccDrawPoly(vertices, 4, true);
#endif // CC_SPRITE_DEBUG_DRAW
if (m_hightlight)
{
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
}
}
2.3 需要纯白高亮显示时,调用setHightlight(true)即可