1 files changed, 63 insertions, 0 deletions
diff --git a/src/instance.c b/src/instance.c
new file mode 100644
index 0000000..e1462b4
--- /dev/null
+++ b/src/instance.c
@@ -0,0 +1,63 @@
+#include "instance.h"
+
+void renderInstance(INSTANCE *instance, SDL_Renderer *renderer) {
+    // Render an instance
+	// Array for projected points
+    POINT projected[instance->model->vertices_length];
+	// Pointers for transformed vertices
+    VERTEX *transformed = malloc(sizeof(VERTEX) * instance->model->vertices_length);
+
+    for (int i = 0; i < instance->model->vertices_length; i++) {
+        // Apply translation and rotation
+        *(transformed + i) = *(instance->model->vertices + i);
+        applyXRotation((transformed + i), *instance->xRotation);
+        applyYRotation((transformed + i), *instance->yRotation);
+        applyZRotation((transformed + i), *instance->zRotation);
+		*(transformed + i) = addVertices((transformed + i), instance->position);
+        // Project vertices
+        projected[i] = projectVertex(transformed + i);
+    }
+    VERTEX n, copyV;
+	// A directional light source
+    VERTEX playerLight = createVertex(0, 0, -1 << FIX_SHIFT);
+    normalizeVertex(&playerLight);
+    TRIANGLE *addr;
+    FIXED intensity;
+    COLOR clr;
+    for (int i = 0; i < instance->model->triangles_length; i++) {
+        // Render the triangle
+        addr = (instance->model->triangles + i);
+        n = computeNormal(transformed, addr);
+        normalizeVertex(&n);
+		// Intensity of light on the triangle
+        intensity = fixed_multiply(dotProduct(&n, &playerLight) + (1 << FIX_SHIFT), 127 << FIX_SHIFT);
+        copyV = *(transformed + addr->v2);
+        normalizeVertex(&copyV);
+
+		// Grayscale color of the triangle from light intensity
+        clr = createColor(intensity >> FIX_SHIFT, intensity >> FIX_SHIFT, intensity >> FIX_SHIFT);
+
+        if (dotProduct(&n, &copyV) < 0) {
+			// The triangle is viewable by the camera
+            drawFilledTriangle(
+                &(projected[addr->v0]),
+                &(projected[addr->v1]),
+                &(projected[addr->v2]),
+                &clr,
+                renderer
+            );
+
+        }
+    }
+	transformed = NULL;
+    free(transformed);
+}
+
+void destroyInstance(INSTANCE *instance) {
+    // Free memory from instance
+	instance->model = NULL;
+	instance->position = NULL;
+	instance->zRotation = NULL;
+	instance->xRotation = NULL;
+	instance->yRotation = NULL;
+}