Added screen clipping.

include/softwareRenderer.h

@@ -20,6 +20,12 @@ class SoftwareRenderer {
         //Draws mesh assuming it is made of triangular primites
         //1.-Gets pointers to render data form mesh
         //2.-Builds MVP 
+        //3.-Iterates through all triangle faces
+        //4.-Runs backface culling algo
+        //5.-Applies vertex shader per vertex
+        //6.-Performs clipping of triangles outside frustrum
+        //7.-Runs perspective divide
+        //8.-
         void drawTriangularMesh(Mesh * triMesh);
 
         void clearBuffers();
@@ -32,11 +38,13 @@ class SoftwareRenderer {
         //Buffer methods
         bool createBuffers(int w, int h);
 
-        //Primitive building methods
+        //Primitive level methods
         void buildTri(Vector3i &f, Vector3f *trianglePrim, std::vector<Vector3f> &vals);
+        void perspectiveDivide(Vector3f *clippedVertices);
 
-        //Culling methods
+        //Culling and clipping methods
         bool backFaceCulling(Vector3f *trianglePrim);
+        bool clipTriangles(Vector3f *clipSpaceVertices);
 
         //Pointer to the scene's target camera
         Camera * mCamera;

include/vector3D.h

@@ -28,6 +28,15 @@ struct Vector3{
     Vector3(T val): x(val), y(val), z(val), w(1) {};
     Vector3(T x1, T y1, T z1) : x(x1), y(y1), z(z1), w(1) {};
     
+    //Homogenous coordinates to cartesian transformation
+    Vector3 &perspectiveDivide(){
+        x /= w;
+        y /= w;
+        z /= w;
+        w  = 1;
+        return *this;
+    }
+
     //Scalar-vector operations
     Vector3 &operator-(){//Negate components of vector
         x = -x;
@@ -63,6 +72,9 @@ struct Vector3{
             y *= factor;
             z *= factor;
         }
+        else {
+            printf("WARNING: Attempting to normalize a vector of length 0.\n");
+        }
 
         return *this;
     }

src/camera.cpp

@@ -10,11 +10,11 @@ Camera::Camera(){
 
 void Camera::update(){
     float t = static_cast<float>(SDL_GetTicks());
-    float radius = 4.0;
+    float radius = 5;
     float camX   = std::sin(t/4000) * radius;
     float camZ   = std::cos(t/4000) * radius;
-    position.x = camX;
-    position.y = 0;
-    position.z = camZ;
-    viewMatrix = Matrix4::lookAt(position,target,up);
+    position.x   = 0;
+    position.y   = 0;
+    position.z   = camZ;
+    viewMatrix   = Matrix4::lookAt(position,target,up);
 }

src/engine.cpp

@@ -92,6 +92,7 @@ void Engine::run(){
         //Stats about frame
         end = SDL_GetTicks();
         printf("%2.1d: Loop elapsed time (ms):%d\n",count,end - start);
+        //break;
     }
     printf("Closing engine\n");
 }

src/matrix.cpp

@@ -26,11 +26,12 @@ Vector3f Matrix4::matMultVec(Vector3f &vec){
     
     //Division is expensive, only do it if you need it
     //Also here is where perspective divide happens!
-    if(w2 != 1){
-        newVec.x /= w2;
-        newVec.y /= w2;
-        newVec.z /= w2;
-    }
+    // if(w2 != 1){
+    //     newVec.x /= w2;
+    //     newVec.y /= w2;
+    //     newVec.z /= w2;
+    // }
+    newVec.w = w2;
 
     return newVec;
 }

src/softwareRenderer.cpp

@@ -47,7 +47,6 @@ void SoftwareRenderer::drawTriangularMesh(Mesh* triMesh){
         //Current vertex and normal indices
         Vector3i f = (*vIndices)[j];
         Vector3i n = (*nIndices)[j];
-        f.print();
 
         //Pack vertex and normal data together into an array
         buildTri(f,trianglePrimitive, *vertices);
@@ -62,7 +61,11 @@ void SoftwareRenderer::drawTriangularMesh(Mesh* triMesh){
             trianglePrimitive[i] = shader.vertex(trianglePrimitive[i], MVP, normalPrim[i], lightDir.normalized(), i);
         }
 
-        //Clipping should occur here
+        //Skip triangles that are outside viewing frustrum
+        //Does not rebuild triangles that are partially out TO DO
+        if (clipTriangles(trianglePrimitive)) continue;
+
+        perspectiveDivide(trianglePrimitive);
 
         //Send to rasterizer which will also call the fragment shader and write to the 
         //zbuffer and pixel buffer.
@@ -121,4 +124,23 @@ bool SoftwareRenderer::backFaceCulling(Vector3f *trianglePrim){
         //Returns false if the triangle cannot see the camera
         float intensity =  N.dotProduct(view_dir);
         return intensity <= 0.0;
+}
+
+bool SoftwareRenderer::clipTriangles(Vector3f *clipSpaceVertices){
+    int count = 0;
+    for(int i = 0; i < 3; ++i){
+        Vector3f vertex = clipSpaceVertices[i];
+        bool inside = (-vertex.w <= vertex.x <= vertex.w ) 
+                    && (-vertex.w <= vertex.y <= vertex.w)
+                    && (0 <= vertex.z <= vertex.w);
+        if (!inside) ++count;
+    }
+    //If count equals three it means every vertex was out so we skip it
+    return count == 3 ;
+}
+
+void SoftwareRenderer::perspectiveDivide(Vector3f *clippedVertices){
+    for(int i = 0; i < 3; ++i){
+        clippedVertices[i] = clippedVertices[i].perspectiveDivide();
+    }
 }