glReadPixels使用縮放移動座標

我想通過使用glReadPixels和C++代碼來選擇兩個點（對角）來讀取像素的矩形。選擇Y軸值時出現問題。glReadPixels使用縮放移動座標

目前，我設法讓glReadPixels工作，直到縮放。當您縮放（放入或縮小）時，該工具從其他Y值讀取像素（X總是OK）

我在做什麼錯？

GLORTHO：

IZDA = mCameraPosition.x - ((double)(rectangleDim.x/SCRARatio)) * mZoomFactor/2; 
DCHA = mCameraPosition.x + ((double)(rectangleDim.x/SCRARatio)) * mZoomFactor/2 
ABAJO = mCameraPosition.y - ((double)rectangleDim.y) * mZoomFactor/2; 
ARRIBA = mCameraPosition.y + ((double)rectangleDim.y) * mZoomFactor/2; 

glOrtho(IZDA, DCHA, ABAJO, ARRIBA, -1.0f, 1.0f);

GETSCREENCOORDS

realDim.x = dimension.x * (dimension.x * mZoomFactor/2); 
realDim.y = dimension.y * (dimension.y * mZoomFactor/2); 

GSC.x = (dimension.x*(x-mCameraPosition.x))/realDim.x; 
GSC.y = (dimension.y/realDim.y) * ((pow(dimension.y, 2)*mZoomFactor/2)+mCameraPosition.y + y - imgDim.y);

GETWORLDCOORDS

realDim.x = dimension.x * (dimension.x * mZoomFactor/2); 
realDim.y = dimension.y * (dimension.y * mZoomFactor/2); 

GWC.x = 
    ((x * realDim.x)/dimension.x) + mCameraPosition.x; 

GWC.y = 
    ((y * realDim.y)/dimension.y) 
    -((dimension.y * (dimension.y * mZoomFactor/2)) + mCameraPosition.y) 
    + imgDim.y;

CHECKFILLVALUE（使用glReadPixels）

ComplexData::Point a, b; 

// Set points screen coordinates 
getScreenCoords(FIP.x, FIP.y); 
a.x = GSC.x; 
a.y = GSC.y; 
getScreenCoords(FEP.x, FEP.y); 
b.x = GSC.x; 
b.y = GSC.y; 

// Set length and width to read (and write) 
double RX_Length, RY_Length; 
if (b.x < a.x) RX_Length = a.x - b.x; 
else RX_Length = b.x - a.x; 
if (b.y < a.y) RY_Length = a.y - b.y; 
else RY_Length = b.y - a.y; 

// Pixel data vector 
float *tdata = new float[3*RX_Length*RY_Length]; 

double desp = (mZoomFactor*dvcamera)/dvzoom; 

getScreenCoords(min(FIP.x, FEP.x), gHeight-FIP.y-2*(mCameraPosition.y-desp)); 
// Reading from the GET SCREEN COORDINATES global values (GSC) 
glReadPixels(GSC.x, GSC.y, RX_Length, RY_Length, GL_RGB, GL_FLOAT, tdata); // <---  Works great until zooming 

glRasterPos2d(min(FIP.x, FEP.x), gHeight-max(FIP.y, FEP.y)); 
glDrawPixels(RX_Length, RY_Length, GL_RGB, GL_FLOAT, tdata); // <--- Works great 
delete[] tdata;

鼠標滾輪（縮放）

Drawing::Point pt = e->Location; 
getWorldCoords(pt.X, pt.Y); 

Initial_Zoom.X = rectangleDim.x - GWC.x; 
Initial_Zoom.Y = GWC.y; 

// ZOOM IN 
if (e->Delta > 0){ 
    if (mZoomFactor > float::Epsilon * 1000.0f){ 
     mZoomFactor /= 1.15f; 
    } 
} 
// ZOOM OUT 
else { 
    if (mZoomFactor < float::MaxValue/1000.0f){ 
     mZoomFactor *= 1.15f; 
    } 
}

來源

2014-02-22 Tarkal

我設法找到解決方案。

替換：

getScreenCoords(min(FIP.x, FEP.x), gHeight-FIP.y-2*(mCameraPosition.y-desp)); 
glReadPixels(GSC.x, GSC.y, RX_Length, RY_Length, GL_RGB, GL_FLOAT, tdata);

有了：

getScreenCoords(std::min(FIP.x, FEP.x), FIP.y); 
glReadPixels(GSC.x, rectangleDim.y - GSC.y, RX, RY, GL_RGB, GL_FLOAT, tdata);

瞧。它的工作原理^^

來源

2014-04-24 16:34:47 Tarkal

glReadPixels使用縮放移動座標

回答

相關問題