Image convolution function ImageKernelConvolution (#3528)

* Added image convultion ImageKernelConvolution

* comment changes

* spelling changes and change to kernel size

* removed kernel normalization inside function

* fix to formating

2 files changed, 143 insertions, 0 deletions

diff --git a/src/raylib.h b/src/raylib.h
index 6ea00300..28f052c7 100644
--- a/src/raylib.h
+++ b/src/raylib.h
@@ -1329,6 +1329,7 @@ RLAPI void ImageAlphaClear(Image *image, Color color, float threshold);
 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 ImageKernelConvolution(Image *image, float* kernel, int kernelSize);                         // Apply Custom Square image convolution kernel
 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
diff --git a/src/rtextures.c b/src/rtextures.c
index 98586db7..8742b0c9 100644
--- a/src/rtextures.c
+++ b/src/rtextures.c
@@ -2082,6 +2082,148 @@ void ImageBlurGaussian(Image *image, int blurSize) {
     ImageFormat(image, format);
 }
 
+// The kernel matrix is assumed to be square. Only supply the width of the kernel.
+void ImageKernelConvolution(Image *image, float* kernel, int kernelSize){
+
+    if ((image->data == NULL) || (image->width == 0) || (image->height == 0) || kernel == NULL) return;
+
+    int kernelWidth = (int)sqrtf((float)kernelSize);
+    if (kernelWidth*kernelWidth != kernelSize)
+    {
+        TRACELOG(LOG_WARNING, "IMAGE: Convolution kernel must be square to be applied");
+        return;
+    }
+
+    Color *pixels = LoadImageColors(*image);
+
+    Vector4 *imageCopy2 = RL_MALLOC((image->height)*(image->width)*sizeof(Vector4));
+    Vector4 *temp = RL_MALLOC(kernelSize*sizeof(Vector4));
+
+
+    for(int i = 0; i < kernelSize; i++){
+        temp[i].x = 0.0f;
+        temp[i].y = 0.0f;
+        temp[i].z = 0.0f;
+        temp[i].w = 0.0f;
+    }
+
+    float rRes = 0.0f;
+    float gRes = 0.0f;
+    float bRes = 0.0f;
+    float aRes = 0.0f;
+
+
+    int startRange, endRange;
+    if(kernelWidth % 2 == 0)
+    {
+        startRange = -kernelWidth/2;
+        endRange = kernelWidth/2;
+    } else 
+    {
+        startRange = -kernelWidth/2;
+        endRange = kernelWidth/2+1;
+    }
+    for(int x = 0; x < image->height; x++) 
+    {
+        for(int y = 0; y < image->width; y++) 
+        {
+
+            for(int xk = startRange; xk < endRange; xk++)
+            {
+                for(int yk = startRange; yk < endRange; yk++)
+                {
+                    int xkabs = xk + kernelWidth/2;
+                    int ykabs = yk + kernelWidth/2;
+                    size_t imgindex = image->width * (x+xk) + (y+yk);
+                    if(imgindex < 0 || imgindex >= image->width * image->height){
+                        temp[kernelWidth * xkabs + ykabs].x = 0.0f;
+                        temp[kernelWidth * xkabs + ykabs].y = 0.0f;
+                        temp[kernelWidth * xkabs + ykabs].z = 0.0f;
+                        temp[kernelWidth * xkabs + ykabs].w = 0.0f;
+                    } else {
+                        temp[kernelWidth * xkabs + ykabs].x = ((float)pixels[imgindex].r)/255.0f * kernel[kernelWidth * xkabs + ykabs];
+                        temp[kernelWidth * xkabs + ykabs].y = ((float)pixels[imgindex].g)/255.0f * kernel[kernelWidth * xkabs + ykabs];
+                        temp[kernelWidth * xkabs + ykabs].z = ((float)pixels[imgindex].b)/255.0f * kernel[kernelWidth * xkabs + ykabs];
+                        temp[kernelWidth * xkabs + ykabs].w = ((float)pixels[imgindex].a)/255.0f * kernel[kernelWidth * xkabs + ykabs];
+                    }
+                }
+            }
+
+            for(int i = 0; i < kernelSize; i++)
+            {
+                rRes += temp[i].x;
+                gRes += temp[i].y;
+                bRes += temp[i].z;
+                aRes += temp[i].w;
+            }
+
+            if(rRes < 0.0f)
+            {
+                rRes = 0.0f;
+            }
+            if(gRes < 0.0f)
+            {
+                gRes = 0.0f;
+            }
+            if(bRes < 0.0f)
+            {
+                bRes = 0.0f;
+            }
+
+            if(rRes > 1.0f)
+            {
+                rRes = 1.0f;
+            }
+            if(gRes > 1.0f)
+            {
+                gRes = 1.0f;
+            }
+             if(bRes > 1.0f)
+            {
+                bRes = 1.0f;
+            }
+
+            imageCopy2[image->width * (x) + (y)].x = rRes;
+            imageCopy2[image->width * (x) + (y)].y = gRes;
+            imageCopy2[image->width * (x) + (y)].z = bRes;
+            imageCopy2[image->width * (x) + (y)].w = aRes;
+
+            rRes = 0.0f;
+            gRes = 0.0f;
+            bRes = 0.0f;
+            aRes = 0.0f;
+
+            for(int i = 0; i < kernelSize; i++)
+            {
+                temp[i].x = 0.0f;
+                temp[i].y = 0.0f;
+                temp[i].z = 0.0f;
+                temp[i].w = 0.0f;
+            }
+        }
+    }
+
+    for (int i = 0; i < (image->width) * (image->height); i++) 
+    {
+        float alpha = (float)imageCopy2[i].w;
+        pixels[i].r = (unsigned char)((imageCopy2[i].x)*255.0f);
+        pixels[i].g = (unsigned char)((imageCopy2[i].y)*255.0f);
+        pixels[i].b = (unsigned char)((imageCopy2[i].z)*255.0f);
+        pixels[i].a = (unsigned char)((alpha)*255.0f);
+        // printf("pixels[%d] = %d", i, pixels[i].r); 
+    }
+
+
+    int format = image->format;
+    RL_FREE(image->data);
+    RL_FREE(imageCopy2);
+    RL_FREE(temp);
+
+    image->data = pixels;
+    image->format = PIXELFORMAT_UNCOMPRESSED_R8G8B8A8;
+    ImageFormat(image, format);
+}
+
 // Generate all mipmap levels for a provided image
 // NOTE 1: Supports POT and NPOT images
 // NOTE 2: image.data is scaled to include mipmap levels