added gradient shader logic to trapezoids

primatives/trapezoid.cpp

@@ -5,6 +5,7 @@
 #include "../datatypes.cpp"
 #include "../helpers.cpp"
 #include "../buffer.cpp"
+#include "../shader.cpp"
 
 namespace UwU {
   // trapezoid (horizontally constrained)
@@ -28,9 +29,7 @@ namespace UwU {
       
       // Draw a horizontally bounded trapezoid
       // y1 >= y0
-      // todo move to private and add public checks
-      void draw (Buffer buffer, Color color) {
-        // printf("(%u, %u, %u, %u, %u, %u)", coords.y0, coords.y1, coords.xl0, coords.xl1, coords.xr0, coords.xr1);
+      void draw (Buffer buffer, Shader shader) {
         uint16_t height = 1 + y1 - y0;
         int16_t LeftBound[height];
         int16_t RightBound[height];
@@ -38,20 +37,51 @@ namespace UwU {
         Helpers::bresenham(0, xl0, y1 - y0, xl1, LeftBound);
         Helpers::bresenham(0, xr0, y1 - y0, xr1, RightBound);
         
-        // printf("leftbound\n");
-        for (uint16_t i = 0; i < height; i++) {
-          // printf("(%u, %u)\n", i, LeftBound[i]);
-        }
-        // printf("rightbound\n");
-        for (uint16_t i = 0; i < height; i++) {
-          // printf("(%u, %u)\n", i, RightBound[i]);
-        }
-        
-        for (uint16_t i = 0; i < height; i++) {
-          for (uint16_t x = LeftBound[i]; x <= RightBound[i]; x++) {
-            // printf("(%u, %u)", x, i + coords.y0);
-            buffer.drawPixel(Coord2(x, i + y0), color);
+        if (shader.shaderType == COLOR) {
+          for (uint16_t i = 0; i < height; i++) {
+            for (uint16_t x = LeftBound[i]; x <= RightBound[i]; x++) {
+              buffer.drawPixel(x, i + y0, shader.c0);
+            }
           }
+          return;
+
+        } else if (shader.shaderType == HGRADIENT) {
+          // find left-right boundaries
+          uint16_t leftmost, rightmost;
+          if (xl0 < xl1) {
+            leftmost = xl0;
+          } else {
+            leftmost = xl1;
+          }
+          if (xr0 > xr1) {
+            rightmost = xr0;
+          } else {
+            rightmost = xr1;
+          }
+
+          // precompute gradient LUT
+          Color cols[rightmost - leftmost];
+          for (uint16_t x = leftmost; x < rightmost; x++) {
+            cols[x - leftmost] = ShaderMethods::gradient(shader.u0, shader.scale, shader.c0, shader.c1, x);
+          }
+
+          for (uint16_t i = 0; i < height; i++) {
+            for (uint16_t x = LeftBound[i]; x <= RightBound[i]; x++) {
+              buffer.drawPixel(x, i + y0, cols[x - leftmost]);
+            }
+          }
+          return;
+
+        } else if (shader.shaderType == VGRADIENT) {
+          Color c;
+          for (uint16_t i = 0; i < height; i++) {
+            c = ShaderMethods::gradient(shader.v0, shader.scale, shader.c0, shader.c1, i + y0);
+            for (uint16_t x = LeftBound[i]; x <= RightBound[i]; x++) {
+              buffer.drawPixel(x, i + y0, c);
+            }
+          }
+          return;
+
         }
         return;
       }