Call Perlin Noise Function

2023-11-13 19:53 UTC gpt-4 Open in ChatGPT ↗

in C++ I have this perlin implementation, how would I go about calling the noise function?

#ifndef PERLIN_H_ #define PERLIN_H_

class Perlin { public: Perlin(); ~Perlin();

// Generates a Perlin (smoothed) noise value between -1 and 1, at the given 3D position.
float noise(float sample_x, float sample_y, float sample_z);

private: int *p; // Permutation table // Gradient vectors float *Gx; float *Gy; float *Gz; };

#endif

To use the noise function from the Perlin class you’ve implemented in C++, you first need to create an instance of the Perlin class and then call the noise function on this instance, passing the required arguments. Here’s a step-by-step guide on how to do it:

Include the Perlin Header: First, ensure that the header file for your Perlin class is included in the source file where you want to use it.
Create an Instance of the Perlin Class: Before you can call the noise function, you need to create an object of the Perlin class.
Call the noise Function: Once you have an instance of Perlin, you can call the noise function with the desired coordinates.

Here is an example of how you might do this in a C++ program:

#include "Perlin.h"  // Include your Perlin header file

int main() {
    // Create an instance of the Perlin class
    Perlin perlinNoise;

    // Coordinates for which you want to generate noise
    float sample_x = 0.5;
    float sample_y = 0.5;
    float sample_z = 0.5;

    // Call the noise function with your coordinates
    float noiseValue = perlinNoise.noise(sample_x, sample_y, sample_z);

    // Do something with the noise value (e.g., print it)
    std::cout << "Perlin Noise Value: " << noiseValue << std::endl;

    return 0;
}

In this example, you’re creating a Perlin object named perlinNoise and then calling its noise function with some sample coordinates. The returned value is stored in noiseValue, which you can then use for whatever purpose you need in your application, like procedural texture generation, height map generation for terrain, etc.

The line of VBA code you provided is a declaration for a Sub (subroutine) named fill, which is located in a DLL (Dynamic Link Library). This declaration allows you to call the fill subroutine from within your VBA code. Let’s break down the components of this line:

Private Declare PtrSafe Sub fill:
- Private means the subroutine is only accessible within the module where it’s declared.
- Declare PtrSafe is used to declare a pointer to a function in a DLL. PtrSafe is used for making the declare compatible with 64-bit versions of Office. It ensures that pointers are of the correct size.
- Sub fill is the name of the subroutine that you are declaring.
Lib "D:\...\libexcel_spotify_test.dll": This specifies the path to the DLL file that contains the fill subroutine.
Parameters:
- ByRef a As Long: This parameter is passed by reference (ByRef). It means that the subroutine fill will receive a reference to the variable, not just a copy of its value. Any changes made to a inside the fill subroutine will affect the original variable that was passed in. As Long indicates that a is of type Long, which is an integer type in VBA.
- ByVal size As Long: This parameter is passed by value (ByVal). It means that the subroutine fill will receive a copy of the variable’s value. Any changes made to size inside the subroutine will not affect the original variable that was passed in. As Long here also indicates that size is an integer type.

In summary, the line declares a VBA subroutine that serves as a wrapper for a function in a DLL. The fill subroutine takes two parameters: the first (a) is an integer passed by reference, and the second (size) is an integer passed by value.

In VBA (Visual Basic for Applications), you cannot directly use As Float because Float is not a defined data type in VBA. The closest equivalents in VBA are Single and Double, which are used for floating-point numbers.

Single represents a single-precision floating-point number. It’s a 32-bit (4-byte) number that can store values from approximately -3.4028235E+38 to -1.401298E-45 for negative values and from 1.401298E-45 to 3.4028235E+38 for positive values.
Double represents a double-precision floating-point number. It’s a 64-bit (8-byte) number with a larger range and precision compared to Single.

Depending on the precision you need for your floating-point calculations, you can choose either Single or Double. For instance, if you were to change your declaration to use a Single, it would look like this:

Private Declare PtrSafe Sub fill Lib "your_dll_path" (ByRef a As Single, ByVal size As Long)

Or, if you need more precision, use Double:

Private Declare PtrSafe Sub fill Lib "your_dll_path" (ByRef a As Double, ByVal size As Long)

Remember that changing the data type in the VBA declaration also requires that the corresponding function in the DLL is expecting a parameter of that type. If the DLL function is expecting a Long and you pass a Single or Double, it could lead to incorrect behavior or a runtime error. Make sure the DLL function’s parameter types align with your VBA declaration.

Assigning an array of floating-point numbers to a grid of cells in Excel using VBA involves a few steps. Here’s a general approach to achieve this:

Define an Array: First, you’ll need to have your array of floating-point numbers ready. This could be a one-dimensional or two-dimensional array, depending on how you want to fill the cells.
Determine the Target Range: Identify the range in the Excel worksheet where you want to place the numbers. The size of this range should match the dimensions of your array.
Assign the Array to the Range: Excel VBA allows you to assign an array directly to a range of cells, which is very efficient for large amounts of data.

Here’s an example to illustrate this process:

Sub FillCells()
    Dim myArray() As Single ' Assuming you are using Single for floating-point numbers
    Dim targetRange As Range
    Dim i As Integer, j As Integer

    ' Example: Creating a 5x5 array of random numbers
    ReDim myArray(1 To 5, 1 To 5)
    For i = 1 To 5
        For j = 1 To 5
            myArray(i, j) = Rnd() ' Assigning random float values
        Next j
    Next i

    ' Set the target range. Here, we are starting from cell A1
    Set targetRange = ThisWorkbook.Sheets("Sheet1").Range("A1:E5")

    ' Assign the array to the range
    targetRange.Value = myArray
End Sub

In this example:

A 5x5 array of type Single (floating-point numbers) is created and filled with random numbers.
The target range is defined as cells A1 to E5 on Sheet1.
The array is then assigned to this range.

Note: Ensure the dimensions of your array match the dimensions of your target range. If they don’t, you’ll get a runtime error. Also, the above example uses the Rnd function to generate random numbers, but you should replace this with your own data source.

If your array is one-dimensional and you want to fill a grid of cells in Excel using VBA, you’ll need to convert or map this 1D array to a 2D array that matches the layout of your target cell range. Excel ranges are inherently two-dimensional (rows and columns), so the direct assignment of a 1D array to a range might not work as expected.

Here’s a method to convert a 1D array to a 2D array and then assign it to a range:

Define Your 1D Array: Have your 1D array of floating-point numbers ready.
Determine the Dimensions of Your Target Range: Decide how you want to map your 1D array into a 2D range (e.g., how many rows and columns).
Create a 2D Array and Populate it with Values from the 1D Array: You’ll need to loop through your 1D array and assign each value to the correct position in the 2D array.
Assign the 2D Array to the Excel Range.

Here’s an example:

Sub FillCellsFrom1DArray()
    Dim oneDArray() As Single
    Dim twoDArray() As Single
    Dim targetRange As Range
    Dim i As Integer, rowCount As Integer, colCount As Integer

    ' Example: Creating a 1D array of 10 random numbers
    ReDim oneDArray(1 To 10)
    For i = 1 To 10
        oneDArray(i) = Rnd() ' Assigning random float values
    Next i

    ' Define the dimensions of your target range
    rowCount = 5 ' Number of rows
    colCount = 2 ' Number of columns

    ' Create and populate the 2D array
    ReDim twoDArray(1 To rowCount, 1 To colCount)
    For i = 1 To UBound(oneDArray)
        twoDArray(((i - 1) Mod rowCount) + 1, ((i - 1) \ rowCount) + 1) = oneDArray(i)
    Next i

    ' Set the target range. Here, it starts from cell A1
    Set targetRange = ThisWorkbook.Sheets("Sheet1").Range("A1").Resize(rowCount, colCount)

    ' Assign the 2D array to the range
    targetRange.Value = twoDArray
End Sub

In this example:

A 1D array oneDArray is created and filled with random numbers.
The dimensions for the target range are defined (5 rows by 2 columns in this case).
A 2D array twoDArray is populated using values from the 1D array.
The 2D array is assigned to the range in the worksheet.

This method works under the assumption that the total number of elements in your 1D array matches the total number of cells in your target range (i.e., rowCount * colCount should equal the size of your 1D array). If they don’t match, you’ll need to handle cases where the array is larger or smaller than the range.

In VBA (Visual Basic for Applications), you can define a single array, which is an array of floating-point numbers of single-precision, in a few different ways depending on whether you know the size of the array beforehand or if it needs to be dynamic. Here are some examples:

Static Array

If you know the size of the array in advance, you can declare it as a static array. For example, to declare a static single array with 10 elements:

Dim myStaticArray(1 To 10) As Single

This creates an array myStaticArray with 10 elements, indexed from 1 to 10.

Dynamic Array

If the size of the array is not known at compile time and you want to set it at runtime, you can declare a dynamic array and then initialize it using the ReDim statement:

Dim myDynamicArray() As Single
ReDim myDynamicArray(1 To 10)

In this case, myDynamicArray is initially declared without a size. Later, ReDim is used to set its size to 10 elements. You can use ReDim later in your code to change the size of the array if needed.

Array Initialization

To initialize an array with specific values, you can assign values to each element individually:

Dim myArray(1 To 5) As Single
myArray(1) = 1.2
myArray(2) = 2.3
myArray(3) = 3.4
myArray(4) = 4.5
myArray(5) = 5.6

Alternatively, for a static array, you can initialize it at the time of declaration:

Dim myArray As Single
myArray = Array(1.2, 2.3, 3.4, 4.5, 5.6)

Using the Array in a Procedure or Function

You can also pass arrays to procedures or functions. For example:

Sub ProcessArray(arr() As Single)
    ' Your code to process the array
End Sub

And call it like this:

Dim myArray(1 To 5) As Single
' Initialize myArray...
ProcessArray myArray

Remember that arrays in VBA are usually base 1 by default (i.e., the first index is 1), but you can change this behavior by using the Option Base statement at the top of your module (before any procedures). For example, Option Base 0 would make arrays zero-based.

this is the c++ function I am trying to call in BVA void fillPerlin(float* array,int res, int cnt, float scale) { Perlin perlinNoise; for(int i=0; i<cnt; i++) { int x = i/res; int y = i%res; float fx = xscale; float fy = yscale; array[i] = perlinNoise.noise(fx,fy,0); } }

And this is the VBA code

Sub TestPerlin() ’ Declaration of an array Dim PerlinArray(1 To 100) As Single Dim targetRange As Range

' Calling the c++ function and passing the FIRST ITEM of the array!
Call fillPerlin(PerlinArray(LBound(PerlinArray)), 10, 100, 0.5)

End Sub

But I keep getting an error of “Wrong number of arguments or invalid property assignment”

why is that

The error message “Wrong number of arguments or invalid property assignment” in VBA typically indicates that the way you’re calling the external function does not match its declaration. This can be due to a mismatch in the number of arguments, their types, or how they’re passed (by value or by reference).

In your case, the C++ function fillPerlin is defined as follows:

void fillPerlin(float* array, int res, int cnt, float scale)

This function expects four parameters:

float* array: A pointer to an array of floats.
int res: An integer.
int cnt: Another integer.
float scale: A floating-point number.

The corresponding declaration in VBA should be made using the Declare statement and should match these parameter types and calling convention (__cdecl is the default calling convention for C++ and it’s compatible with VBA’s default). However, VBA does not support pointers in the same way as C or C++. Instead, it passes the first element of an array when you need to pass an array to a DLL function. The corrected VBA declaration might look something like this:

Private Declare PtrSafe Sub fillPerlin Lib "path_to_dll.dll" (ByRef array As Single, ByVal res As Long, ByVal cnt As Long, ByVal scale As Single)

In your VBA function, when you call fillPerlin, ensure you’re passing the first element of the array by reference:

Sub TestPerlin()
    Dim PerlinArray(1 To 100) As Single
    Dim targetRange As Range

    ' Call the C++ function with the first element of the array
    Call fillPerlin(PerlinArray(1), 10, 100, 0.5)
End Sub

This setup passes the address of the first element of PerlinArray to the C++ function, which then interprets it as a pointer to an array of 100 floats.

Remember, the DLL and the VBA host (Excel) must be compatible in terms of architecture (32-bit or 64-bit). If you are using a 64-bit version of Excel, your DLL should also be compiled for 64-bit. The PtrSafe keyword is used to indicate that the declare statement is safe to run in 64-bit versions. If you are using a 32-bit version of Excel, you should remove PtrSafe and ensure your DLL is compiled for 32-bit.

In VBA (Visual Basic for Applications), you can use a While...Wend loop to execute a series of statements as long as a given condition is true. The basic syntax of a While...Wend loop is as follows:

While condition
    ' Statements to execute while the condition is true
Wend

Here, condition is a Boolean expression that is evaluated before each iteration of the loop. If condition is True, the statements inside the loop are executed. The loop continues until condition becomes False.

Example of a `While...Wend` Loop

Let’s say you want to loop through numbers starting from 1 and keep adding them until the total sum reaches or exceeds 100. Here’s how you could do it using a While...Wend loop in VBA:

Sub ExampleWhileLoop()
    Dim sum As Integer
    Dim i As Integer

    sum = 0
    i = 1

    While sum < 100
        sum = sum + i
        i = i + 1
    Wend

    MsgBox "The total sum is: " & sum
End Sub

In this example:

The loop will keep running as long as sum < 100.
Within each iteration, the loop adds the current value of i to sum and then increments i by 1.
When the sum reaches or exceeds 100, the loop terminates, and a message box displays the total sum.

Important Notes

Ensure that the loop has a proper exit condition to prevent an infinite loop.
You can also use a Do...Loop structure in VBA, which offers more flexibility, such as Do While...Loop, Do Until...Loop, Do...Loop While, and Do...Loop Until.

Choose the type of loop that best fits your specific scenario and coding style.

In Excel, there isn’t a direct feature to make text completely transparent in a cell. However, you can achieve a similar effect by setting the text color to the same color as the cell’s background, effectively making the text ‘invisible’ or ‘transparent’ against the background. Here’s how you can do it:

Select the Cell(s): Click on the cell or range of cells where you want to apply this effect.
Change the Text Color to Match the Background:
- Go to the Home tab on the Ribbon.
- In the Font group, click the arrow next to the Font Color button.
- Choose the color that matches the cell’s background. If the background is white (default), choose white as the font color.
Using Conditional Formatting for Dynamic Transparency:
- If the background color of the cell changes dynamically (e.g., through conditional formatting), you can create a conditional formatting rule that also changes the font color to match the new background color.
- Go to the Home tab, select Conditional Formatting, and then create a new rule.
- Use a formula to determine which cells to format and set the format to change the font color to match the background color.
Making Text Invisible in Printed Documents:
- If your goal is to make certain texts invisible in a printed document, simply set the font color to white or the same as the background. This text will not appear when printed, although it will still be present in the Excel file.

Remember, while the text may not be visible, it still exists in the cell and will appear in the formula bar when the cell is selected. It will also be included in any calculations or references involving that cell.

Conditional Formatting in Excel is a powerful tool that allows you to apply specific formatting to cells based on certain conditions or criteria. If you want to dynamically change the text color in a cell to match the background color (essentially making it ‘invisible’ under certain conditions), you can use Conditional Formatting. Here’s a detailed explanation of how you can set this up:

Step 1: Select the Range of Cells

First, select the cells to which you want to apply the conditional formatting. This could be a single cell, a range of cells, or even entire rows or columns.

Step 2: Access Conditional Formatting

Go to the ‘Home’ tab on the Excel Ribbon.
In the ‘Styles’ group, click on ‘Conditional Formatting’.

Step 3: Create a New Rule

From the dropdown menu of Conditional Formatting, choose ‘New Rule’.
In the New Formatting Rule dialog box, select ‘Use a formula to determine which cells to format’.

Step 4: Enter the Condition

In the formula box, enter the condition under which you want the text to become ‘invisible’.
For example, if you want the text to be invisible when the cell value is greater than 100, you would enter =A1>100 (assuming A1 is the first cell in your selected range).
This formula should be adjusted based on your specific criteria.

Step 5: Set the Format

Click on the ‘Format’ button.
In

In VBA for Excel, there is no direct function that “disables font rendering” in the sense of completely stopping text from being rendered in a cell. However, you can achieve a similar effect by making the font color the same as the cell’s background color, effectively hiding the text. This can be done programmatically using VBA.

Here’s an example VBA function that sets the font color of a specified range to the cell’s background color, effectively hiding the text:

Sub HideTextInCells(rng As Range)
    Dim cell As Range

    For Each cell In rng
        cell.Font.Color = cell.Interior.Color
    Next cell
End Sub

You can call this function and pass the range where you want to hide the text. For example:

Sub TestHideText()
    HideTextInCells ThisWorkbook.Sheets("Sheet1").Range("A1:A10")
End Sub

This will make the text in cells A1 through A10 of “Sheet1” the same color as their background, making the text ‘invisible’.

Remember, this method does not technically disable font rendering; it just changes the font color to match the background color, making the text appear invisible. The text is still there and can be seen in the formula bar when the cell is selected, or by changing the font or background color.

In Microsoft Excel, the concept of “color depth” typically pertains to digital images and their ability to represent colors. However, when talking about Excel cells, we usually refer to the colors that can be applied to the cell’s background or font.

Excel does not explicitly define a color depth for cells in the same way that it is defined for digital images (like 24-bit or 32-bit color depth), but it supports a wide range of colors, often matching the color capabilities of your computer’s display system.

Excel Color Palette:

Excel 2007 and later versions support the 24-bit color, meaning you can theoretically have over 16 million different colors (256 red x 256 green x 256 blue). This is often referred to as “True Color” in digital graphics.
Excel 2003 and earlier versions used a more limited color palette, typically around 56 colors.

Using Colors in Excel:

When you format a cell’s background or font color, you can choose from a theme, standard colors, or create a custom color.
For custom colors, you have the option to specify RGB (Red, Green, Blue) values, each ranging from 0 to 255, which aligns with the 24-bit color standard.
Additionally, you can specify colors using Hex color codes, commonly used in web design and digital graphics.

Practical Limitations:

The actual display of colors will depend on your monitor’s capabilities and settings. Most modern monitors support at least 24-bit color.
Excel’s user interface for selecting colors (especially in versions prior to 2007) might not visually display all possible 16 million+ colors, but custom colors can be defined using RGB values.

In summary, while Excel doesn’t explicitly state “color depth” for cells, it supports a wide range of colors consistent with 24-bit color depth, allowing for over 16 million color variations.