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Added Box and Gaussian blurring (#2770)

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* Added Box and Gaussian blurring

* Removed dependence of gaussian blur to box blur & Fixed precision errors

Co-authored-by: nobytesgiven <nobytesgiven@users.noreply.github.com>
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nobytesgiven 2022-10-25 18:56:06 +03:00 committed by GitHub
parent 072e92615a
commit dbecb95024
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2 changed files with 158 additions and 0 deletions
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1
src/raylib.h
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@ -1258,6 +1258,7 @@ RLAPI void ImageAlphaCrop(Image *image, float threshold);
RLAPI void ImageAlphaClear(Image *image, Color color, float threshold); // Clear alpha channel to desired color
RLAPI void ImageAlphaMask(Image *image, Image alphaMask); // Apply alpha mask to image
RLAPI void ImageAlphaPremultiply(Image *image); // Premultiply alpha channel
RLAPI void ImageBlurGaussian(Image *image, int blurSize); // Apply Gaussian blur using a box blur approximation
RLAPI void ImageResize(Image *image, int newWidth, int newHeight); // Resize image (Bicubic scaling algorithm)
RLAPI void ImageResizeNN(Image *image, int newWidth,int newHeight); // Resize image (Nearest-Neighbor scaling algorithm)
RLAPI void ImageResizeCanvas(Image *image, int newWidth, int newHeight, int offsetX, int offsetY, Color fill); // Resize canvas and fill with color

157
src/rtextures.c
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@ -194,6 +194,10 @@
#define PIXELFORMAT_UNCOMPRESSED_R5G5B5A1_ALPHA_THRESHOLD 50 // Threshold over 255 to set alpha as 0
#endif
#ifndef GAUSSIAN_BLUR_ITERATIONS
#define GAUSSIAN_BLUR_ITERATIONS 4 // Number of box blur iterations to approximate gaussian blur
#endif
//----------------------------------------------------------------------------------
// Types and Structures Definition
//----------------------------------------------------------------------------------
@ -1494,6 +1498,159 @@ void ImageAlphaPremultiply(Image *image)
ImageFormat(image, format);
}
// Apply box blur
void ImageBlurGaussian(Image *image, int blurSize) {
// Security check to avoid program crash
if ((image->data == NULL) || (image->width == 0) || (image->height == 0)) return;
ImageAlphaPremultiply(image);
Color *pixels = LoadImageColors(*image);
Color *pixelsCopy = LoadImageColors(*image);
// Loop switches between pixelsCopy1 and pixelsCopy2
Vector4 *pixelsCopy1 = RL_MALLOC((image->height)*(image->width)*sizeof(Vector4));
Vector4 *pixelsCopy2 = RL_MALLOC((image->height)*(image->width)*sizeof(Vector4));
for (int i = 0; i < (image->height)*(image->width); i++) {
pixelsCopy1[i].x = pixels[i].r;
pixelsCopy1[i].y = pixels[i].g;
pixelsCopy1[i].z = pixels[i].b;
pixelsCopy1[i].w = pixels[i].a;
}
// Repeated convolution of rectangular window signal by itself converges to a gaussian distribution
for (int j = 0; j < GAUSSIAN_BLUR_ITERATIONS; j++) {
// Horizontal motion blur
for (int row = 0; row < image->height; row++)
{
float avgR = 0.0f;
float avgG = 0.0f;
float avgB = 0.0f;
float avgAlpha = 0.0f;
int convolutionSize = blurSize+1;
for (int i = 0; i < blurSize+1; i++)
{
avgR += pixelsCopy1[row*image->width + i].x;
avgG += pixelsCopy1[row*image->width + i].y;
avgB += pixelsCopy1[row*image->width + i].z;
avgAlpha += pixelsCopy1[row*image->width + i].w;
}
pixelsCopy2[row*image->width].x = avgR/convolutionSize;
pixelsCopy2[row*image->width].y = avgG/convolutionSize;
pixelsCopy2[row*image->width].z = avgB/convolutionSize;
pixelsCopy2[row*image->width].w = avgAlpha/convolutionSize;
for (int x = 1; x < image->width; x++)
{
if (x-blurSize >= 0)
{
avgR -= pixelsCopy1[row*image->width + x-blurSize].x;
avgG -= pixelsCopy1[row*image->width + x-blurSize].y;
avgB -= pixelsCopy1[row*image->width + x-blurSize].z;
avgAlpha -= pixelsCopy1[row*image->width + x-blurSize].w;
convolutionSize--;
}
if (x+blurSize < image->width)
{
avgR += pixelsCopy1[row*image->width + x+blurSize].x;
avgG += pixelsCopy1[row*image->width + x+blurSize].y;
avgB += pixelsCopy1[row*image->width + x+blurSize].z;
avgAlpha += pixelsCopy1[row*image->width + x+blurSize].w;
convolutionSize++;
}
pixelsCopy2[row*image->width + x].x = avgR/convolutionSize;
pixelsCopy2[row*image->width + x].y = avgG/convolutionSize;
pixelsCopy2[row*image->width + x].z = avgB/convolutionSize;
pixelsCopy2[row*image->width + x].w = avgAlpha/convolutionSize;
}
}
// Vertical motion blur
for (int col = 0; col < image->width; col++)
{
float avgR = 0.0f;
float avgG = 0.0f;
float avgB = 0.0f;
float avgAlpha = 0.0f;
int convolutionSize = blurSize+1;
for (int i = 0; i < blurSize+1; i++)
{
avgR += pixelsCopy2[i*image->width + col].x;
avgG += pixelsCopy2[i*image->width + col].y;
avgB += pixelsCopy2[i*image->width + col].z;
avgAlpha += pixelsCopy2[i*image->width + col].w;
}
pixelsCopy1[col].x = (unsigned char) (avgR/convolutionSize);
pixelsCopy1[col].y = (unsigned char) (avgG/convolutionSize);
pixelsCopy1[col].z = (unsigned char) (avgB/convolutionSize);
pixelsCopy1[col].w = (unsigned char) (avgAlpha/convolutionSize);
for (int y = 1; y < image->height; y++)
{
if (y-blurSize >= 0)
{
avgR -= pixelsCopy2[(y-blurSize)*image->width + col].x;
avgG -= pixelsCopy2[(y-blurSize)*image->width + col].y;
avgB -= pixelsCopy2[(y-blurSize)*image->width + col].z;
avgAlpha -= pixelsCopy2[(y-blurSize)*image->width + col].w;
convolutionSize--;
}
if (y+blurSize < image->height)
{
avgR += pixelsCopy2[(y+blurSize)*image->width + col].x;
avgG += pixelsCopy2[(y+blurSize)*image->width + col].y;
avgB += pixelsCopy2[(y+blurSize)*image->width + col].z;
avgAlpha += pixelsCopy2[(y+blurSize)*image->width + col].w;
convolutionSize++;
}
pixelsCopy1[y*image->width + col].x = (unsigned char) (avgR/convolutionSize);
pixelsCopy1[y*image->width + col].y = (unsigned char) (avgG/convolutionSize);
pixelsCopy1[y*image->width + col].z = (unsigned char) (avgB/convolutionSize);
pixelsCopy1[y*image->width + col].w = (unsigned char) (avgAlpha/convolutionSize);
}
}
}
// Reverse premultiply
for (int i = 0; i < (image->width)*(image->height); i++)
{
if (pixelsCopy1[i].w == 0)
{
pixels[i].r = 0;
pixels[i].g = 0;
pixels[i].b = 0;
pixels[i].a = 0;
}
else if (pixelsCopy1[i].w < 255.0f)
{
float alpha = (float)pixelsCopy1[i].w/255.0f;
pixels[i].r = (unsigned char)((float)pixelsCopy1[i].x/alpha);
pixels[i].g = (unsigned char)((float)pixelsCopy1[i].y/alpha);
pixels[i].b = (unsigned char)((float)pixelsCopy1[i].z/alpha);
pixels[i].a = (unsigned char) pixelsCopy1[i].w;
}
}
int format = image->format;
RL_FREE(image->data);
RL_FREE(pixelsCopy1);
RL_FREE(pixelsCopy2);
image->data = pixels;
image->format = PIXELFORMAT_UNCOMPRESSED_R8G8B8A8;
ImageFormat(image, format);
}
// Resize and image to new size
// NOTE: Uses stb default scaling filters (both bicubic):
// STBIR_DEFAULT_FILTER_UPSAMPLE STBIR_FILTER_CATMULLROM