added alpha blending and putPixel helper function

test.cpp

@@ -46,7 +46,26 @@ namespace UwU {
   class Draw {
     private:
 
-      // plot lines if m<= 1
+      uint8_t lerp8(uint8_t a, uint8_t b, uint8_t t) {
+        uint16_t product = (a * (255 - t)) + (b * t);
+        return product / 255;
+      }
+
+      void putPixel(uint32_t x, uint32_t y, uint8_t r, uint8_t g, uint8_t b, uint8_t a = 0xff) {
+          size_t i = (size_t)y * waymini_get_stride(this->wm) + (size_t)x * 4;
+          uint8_t b0 = this->pixels[i + 0];
+          uint8_t g0 = this->pixels[i + 1];
+          uint8_t r0 = this->pixels[i + 2];
+          b = lerp8(b0, b, a);
+          g = lerp8(g0, g, a);
+          r = lerp8(r0, r, a);
+          this->pixels[i + 0] = b;    // B
+          this->pixels[i + 1] = g;    // G
+          this->pixels[i + 2] = r;    // R
+          this->pixels[i + 3] = 0xff; // A
+      }
+
+      // plot lines if m <= 1
       void lineLow(int32_t x0, int32_t y0, int32_t x1, int32_t y1, Color color) {
         int32_t dx = x1 - x0;
         int32_t dy = y1 - y0;
@@ -58,11 +77,7 @@ namespace UwU {
         int32_t d = (2 * dy) - dx;
         int32_t y = y0;
         for (int32_t x = x0; x < x1; x++) {
-          size_t i = (size_t)y * waymini_get_stride(this->wm) + (size_t)x * 4;
+          putPixel(x, y, color.r, color.g, color.b, color.a);
-          this->pixels[i + 0] = color.b;  // B
-          this->pixels[i + 1] = color.g;  // G
-          this->pixels[i + 2] = color.r;  // R
-          this->pixels[i + 3] = 0xFF;     // A
           if (d > 0) {
             y += yi;
             d += (2 * (dy - dx));
@@ -73,7 +88,7 @@ namespace UwU {
         return;
       }
 
-      // plot lines if m<= 1
+      // plot lines if m >1
       void lineHigh(int32_t x0, int32_t y0, int32_t x1, int32_t y1, Color color) {
         int32_t dx = x1 - x0;
         int32_t dy = y1 - y0;
@@ -85,11 +100,7 @@ namespace UwU {
         int32_t d = (2 * dx) - dy;
         int32_t x = x0;
         for (int32_t y = y0; y < y1; y++) {
-          size_t i = (size_t)y * waymini_get_stride(this->wm) + (size_t)x * 4;
+          putPixel(x, y, color.r, color.g, color.b, color.a);
-          this->pixels[i + 0] = color.b;  // B
-          this->pixels[i + 1] = color.g;  // G
-          this->pixels[i + 2] = color.r;  // R
-          this->pixels[i + 3] = 0xFF;     // A
           if (d > 0) {
             x += xi;
             d += (2 * (dx - dy));
@@ -128,11 +139,7 @@ namespace UwU {
         if (point0.x > this->width || point0.y > this->height || point1.x > this->width || point1.y > this->height) {return;};
         for (uint32_t y = point0.y; y < point1.y; y++) {
           for (uint32_t x = point0.x; x < point1.x; x++) {
-            size_t i = (size_t)y * waymini_get_stride(this->wm) + (size_t)x * 4;
+            putPixel(x, y, color.r, color.g, color.b, color.a);
-            this->pixels[i + 0] = color.b;  // B
-            this->pixels[i + 1] = color.g;  // G
-            this->pixels[i + 2] = color.r;  // R
-            this->pixels[i + 3] = 0xFF;     // A
           }
         }
         return;
@@ -154,11 +161,7 @@ namespace UwU {
       // Draw a single point
       void point (Coord2 point, Color color) {
         if (point.x > this->width || point.y > this->height) {return;};
-        size_t i = (size_t)point.y * waymini_get_stride(this->wm) + (size_t)point.x * 4;
+        putPixel(point.x, point.y, color.r, color.g, color.b, color.a);
-        this->pixels[i + 0] = color.b;  // B
-        this->pixels[i + 1] = color.g;  // G
-        this->pixels[i + 2] = color.r;  // R
-        this->pixels[i + 3] = 0xFF;     // A
       }
 
       // Uses Bresenham's line algorithm to draw line of any slope
@@ -187,8 +190,8 @@ namespace UwU {
 
 int main(void) {
   uint32_t w = 800, h = 480;
-  UwU::Color fuchsia = UwU::Color(0xb00b69ff);
+  UwU::Color fuchsia = UwU::Color(0xb00b6980);
-  UwU::Color green = UwU::Color(0x00ff00ff);
+  UwU::Color green = UwU::Color(0x00ff0060);
   printf("r: %u, g:%u, b:%u, a:%u\n", fuchsia.r, fuchsia.g, fuchsia.b, fuchsia.a);
 
   // struct waymini *wm = waymini_create(w, h, on_key, NULL);