/*************************************************************************
Get a ColorRectangle from the specified Region
*************************************************************************/
ColorRect ColorRect::getSubRectangle( float left, float right, float top, float bottom ) const
{
return ColorRect(
getColorAtPoint(left, top),
getColorAtPoint(right, top),
getColorAtPoint(left, bottom),
getColorAtPoint(right, bottom)
);
}
void DrawStreamlinesImplementation::drawStreamline(
Vec2D<float> point, float dir, const Grid<Vec2D<float>>& vector_field,
const Grid<float>& scalar_field, float z) {
Vec2D<float> gridpoint{point.x * (vector_field.x() - 1),
point.y * (vector_field.y() - 1)};
vector<float> vertices;
vector<float> colors;
Vec2D<float> v1 = interpolate(vector_field, point);
v1 *= dir;
addVertices(vertices, colors, gridpoint, v1,
getColorAtPoint(vector_field, scalar_field, point), z);
Vec2D<float> last_point = gridpoint;
bool early_exit = false;
for (size_t i = 0; i < vector_field.x() * 3 && early_exit == false; i++) {
Vec2D<float> v1 =
interpolate(vector_field, {gridpoint.x / (vector_field.x() - 1),
gridpoint.y / (vector_field.y() - 1)});
v1 *= dir;
// Calculate the predictor point and get the direction at that point.
Vec2D<float> predictor = step(gridpoint, v1);
Vec2D<float> v2 =
interpolate(vector_field, {predictor.x / (vector_field.x() - 1),
predictor.y / (vector_field.y() - 1)});
v2 *= dir;
v1 = (v1 + v2) / 2.0;
if (v1.x * v1.x + v1.y * v1.y < 0.0000001) early_exit = true;
gridpoint = step(gridpoint, v1);
if (gridpoint.x < BORDER_PADDING) {
gridpoint.x = BORDER_PADDING;
early_exit = true;
}
if (gridpoint.x > vector_field.x() - BORDER_PADDING) {
gridpoint.x = vector_field.x() - BORDER_PADDING;
early_exit = true;
}
if (gridpoint.y < BORDER_PADDING ||
gridpoint.y > vector_field.y() - BORDER_PADDING)
early_exit = true;
auto point = Vec2D<float>{gridpoint.x / (vector_field.x() - 1),
gridpoint.y / (vector_field.y() - 1)};
v1 = interpolate(vector_field, point);
v1 = v1.normalize();
v1 *= dir;
if (early_exit || (gridpoint - last_point).normalize() * v1 < 0.99999999) {
addVertices(vertices, colors, gridpoint, v1,
getColorAtPoint(vector_field, scalar_field, point), z);
last_point = gridpoint;
}
}
glEnableClientState(GL_COLOR_ARRAY);
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, (float*)vertices.data());
glColorPointer(4, GL_FLOAT, 0, (float*)colors.data());
glDrawArrays(GL_TRIANGLE_STRIP, 0, vertices.size() / 3);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_COLOR_ARRAY);
}
