void GraphicsContext3D::readPixelsIMG(GC3Dint x, GC3Dint y, GC3Dsizei width, GC3Dsizei height, GC3Denum format, GC3Denum type, void* data)
{
// Currently only format=RGBA, type=UNSIGNED_BYTE is supported by the specification: http://www.khronos.org/registry/webgl/specs/latest/
// If this ever changes, this code will need to be updated.
// Calculate the strides of our data and canvas
unsigned formatSize = 4; // RGBA UNSIGNED_BYTE
unsigned dataStride = width * formatSize;
unsigned canvasStride = m_currentWidth * formatSize;
// If we are using a pack alignment of 8, then we need to align our strides to 8 byte boundaries
// See: http://en.wikipedia.org/wiki/Data_structure_alignment (computing padding)
int packAlignment;
glGetIntegerv(GL_PACK_ALIGNMENT, &packAlignment);
if (8 == packAlignment) {
dataStride = (dataStride + 7) & ~7;
canvasStride = (canvasStride + 7) & ~7;
}
unsigned char* canvasData = new unsigned char[canvasStride * m_currentHeight];
::glReadPixels(0, 0, m_currentWidth, m_currentHeight, format, type, canvasData);
// If we failed to read our canvas data due to a GL error, don't continue
int error = glGetError();
if (GL_NO_ERROR != error) {
synthesizeGLError(error);
return;
}
// Clear our data in case some of it lies outside the bounds of our canvas
// TODO: don't do this if all of the data lies inside the bounds of the canvas
memset(data, 0, dataStride * height);
// Calculate the intersection of our canvas and data bounds
IntRect dataRect(x, y, width, height);
IntRect canvasRect(0, 0, m_currentWidth, m_currentHeight);
IntRect nonZeroDataRect = intersection(dataRect, canvasRect);
unsigned xDataOffset = x < 0 ? -x * formatSize : 0;
unsigned yDataOffset = y < 0 ? -y * dataStride : 0;
unsigned xCanvasOffset = nonZeroDataRect.x() * formatSize;
unsigned yCanvasOffset = nonZeroDataRect.y() * canvasStride;
unsigned char* dst = static_cast<unsigned char*>(data) + xDataOffset + yDataOffset;
unsigned char* src = canvasData + xCanvasOffset + yCanvasOffset;
for (int row = 0; row < nonZeroDataRect.height(); row++) {
memcpy(dst, src, nonZeroDataRect.width() * formatSize);
dst += dataStride;
src += canvasStride;
}
delete [] canvasData;
}
Vec2 g_randomPosition(const Vec2& posStart)
{
Size winSize = Director::getInstance()->getWinSize();
Rect canvasRect(0.0f, 0.0f, winSize.width-100.0f, winSize.height-200.0f);
return g_randomPosition(posStart, canvasRect);
}
