grSurfaceAltitudeColor (Example)

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Drawing a surface chart

grSurfaceAltitudeColor (Example)

See the associated help page

Drawing a surface chart

This example is used to draw a surface chart representing the lightness of an image. The chart is drawn in the "CHART_Surface" control.

x, y, z are real
wImage is Image

// Load the photo found in memory in an Image variable
wImage = "sunset.jpg"

// Display the photo
IMG_photo = wImage

// Erase the previous chart
grClearPict(CHART_Surface)
// Delete data from the previous chart
grDeleteSeries(CHART_Surface)

// Delete the different colors of the previous altitudes
grSurfaceDeleteAltitudeColor(CHART_Surface, 0)
grSurfaceDeleteAltitudeColor(CHART_Surface, 33)
grSurfaceDeleteAltitudeColor(CHART_Surface, 66)
grSurfaceDeleteAltitudeColor(CHART_Surface, 100)

IF CBOX_Color THEN
// Chart in color
grSurfaceAltitudeColor(CHART_Surface, 0, PastelBlue)
grSurfaceAltitudeColor(CHART_Surface, 33, PastelGreen)
grSurfaceAltitudeColor(CHART_Surface, 66, PastelYellow)
grSurfaceAltitudeColor(CHART_Surface, 100, PastelRed)
ELSE
// Chart in Black & White
grSurfaceAltitudeColor(CHART_Surface, 0, Black)
grSurfaceAltitudeColor(CHART_Surface, 100, White)
END

// Scan the image and all the points
// to define the rate of lightness for the point
// via ColorLightness
FOR I = 1 _TO_ wImage.Width STEP 4
FOR j = 1 _TO_ wImage.Height STEP 4
x = I
y = j
z = ColorLightness(dPixelColor(wImage, x, y))
grSurfaceAddData(CHART_Surface, x, y, z)
END
END

// Performs a slight rotation of 35°
// to highlight the raised effect
grRotation(CHART_Surface, grAxisX, -35)

// Draws the chart in the Chart control
grDraw(CHART_Surface)