// drawing line between 2 points from left to right // papb -> pcpd // pa, pb, pc, pd must then be sorted before void ProcessScanLine(ScanLineData data, Vertex va, Vertex vb, Vertex vc, Vertex vd, Color4 color) { Vector3 pa = va.Coordinates; Vector3 pb = vb.Coordinates; Vector3 pc = vc.Coordinates; Vector3 pd = vd.Coordinates; // Thanks to current Y, we can compute the gradient to compute others values like // the starting X (sx) and ending X (ex) to draw between // if pa.Y == pb.Y or pc.Y == pd.Y, gradient is forced to 1 var gradient1 = pa.Y != pb.Y ? (data.currentY - pa.Y) / (pb.Y - pa.Y) : 1; var gradient2 = pc.Y != pd.Y ? (data.currentY - pc.Y) / (pd.Y - pc.Y) : 1; int sx = (int)Interpolate(pa.X, pb.X, gradient1); int ex = (int)Interpolate(pc.X, pd.X, gradient2); // starting Z & ending Z float z1 = Interpolate(pa.Z, pb.Z, gradient1); float z2 = Interpolate(pc.Z, pd.Z, gradient2); var snl = Interpolate(data.ndotla, data.ndotlb, gradient1); var enl = Interpolate(data.ndotlc, data.ndotld, gradient2); // drawing a line from left (sx) to right (ex) for (var x = sx; x < ex; x++) { float gradient = (x - sx) / (float)(ex - sx); var z = Interpolate(z1, z2, gradient); var ndotl = Interpolate(snl, enl, gradient); // changing the color value using the cosine of the angle // between the light vector and the normal vector DrawPoint(new Vector3(x, data.currentY, z), color * ndotl); } }
// drawing line between 2 points from left to right // papb -> pcpd // pa, pb, pc, pd must then be sorted before void ProcessScanLine(ScanLineData data, Vertex va, Vertex vb, Vertex vc, Vertex vd, Color4 color, Texture texture) { Vector3 pa = va.Coordinates; Vector3 pb = vb.Coordinates; Vector3 pc = vc.Coordinates; Vector3 pd = vd.Coordinates; // Thanks to current Y, we can compute the gradient to compute others values like // the starting X (sx) and ending X (ex) to draw between // if pa.Y == pb.Y or pc.Y == pd.Y, gradient is forced to 1 var gradient1 = pa.Y != pb.Y ? (data.currentY - pa.Y) / (pb.Y - pa.Y) : 1; var gradient2 = pc.Y != pd.Y ? (data.currentY - pc.Y) / (pd.Y - pc.Y) : 1; int sx = (int)Interpolate(pa.X, pb.X, gradient1); int ex = (int)Interpolate(pc.X, pd.X, gradient2); // starting Z & ending Z float z1 = Interpolate(pa.Z, pb.Z, gradient1); float z2 = Interpolate(pc.Z, pd.Z, gradient2); // Interpolating normals on Y var snl = Interpolate(data.ndotla, data.ndotlb, gradient1); var enl = Interpolate(data.ndotlc, data.ndotld, gradient2); // Interpolating texture coordinates on Y var su = Interpolate(data.ua, data.ub, gradient1); var eu = Interpolate(data.uc, data.ud, gradient2); var sv = Interpolate(data.va, data.vb, gradient1); var ev = Interpolate(data.vc, data.vd, gradient2); // drawing a line from left (sx) to right (ex) for (var x = sx; x < ex; x++) { float gradient = (x - sx) / (float)(ex - sx); // Interpolating Z, normal and texture coordinates on X var z = Interpolate(z1, z2, gradient); var ndotl = Interpolate(snl, enl, gradient); var u = Interpolate(su, eu, gradient); var v = Interpolate(sv, ev, gradient); Color4 textureColor; if (texture != null) { textureColor = texture.Map(u, v); } else { textureColor = new Color4(1, 1, 1, 1); } // changing the native color value using the cosine of the angle // between the light vector and the normal vector // and the texture color DrawPoint(new Vector3(x, data.currentY, z), color * ndotl * textureColor); } }
private void DrawLeftTriangle( Color4 colour, Texture texture, Vector3 p1, Vector3 p2, Vector3 p3, Vertex v1, Vertex v2, Vertex v3, float nl1, float nl2, float nl3) { var data = new ScanLineData(); for (var y = (int)p1.Y; y <= (int)p3.Y; y++) { data.currentY = y; if (y < p2.Y) { data.ndotla = nl1; data.ndotlb = nl2; data.ndotlc = nl1; data.ndotld = nl3; data.ua = v1.TextureCoordinates.X; data.ub = v2.TextureCoordinates.X; data.uc = v1.TextureCoordinates.X; data.ud = v3.TextureCoordinates.X; data.va = v1.TextureCoordinates.Y; data.vb = v2.TextureCoordinates.Y; data.vc = v1.TextureCoordinates.Y; data.vd = v3.TextureCoordinates.Y; ProcessScanLine(data, v1, v2, v1, v3, colour, texture); } else { data.ndotla = nl2; data.ndotlb = nl3; data.ndotlc = nl1; data.ndotld = nl3; data.ua = v2.TextureCoordinates.X; data.ub = v3.TextureCoordinates.X; data.uc = v1.TextureCoordinates.X; data.ud = v3.TextureCoordinates.X; data.va = v2.TextureCoordinates.Y; data.vb = v3.TextureCoordinates.Y; data.vc = v1.TextureCoordinates.Y; data.vd = v3.TextureCoordinates.Y; ProcessScanLine(data, v2, v3, v1, v3, colour, texture); } } }
public void DrawTriangle(Vertex v1, Vertex v2, Vertex v3, Color4 color, Texture texture) { // Sorting the points in order to always have this order on screen p1, p2 & p3 // with p1 always up (thus having the Y the lowest possible to be near the top screen) // then p2 between p1 & p3 if (v1.Coordinates.Y > v2.Coordinates.Y) { var temp = v2; v2 = v1; v1 = temp; } if (v2.Coordinates.Y > v3.Coordinates.Y) { var temp = v2; v2 = v3; v3 = temp; } if (v1.Coordinates.Y > v2.Coordinates.Y) { var temp = v2; v2 = v1; v1 = temp; } Vector3 p1 = v1.Coordinates; Vector3 p2 = v2.Coordinates; Vector3 p3 = v3.Coordinates; // Light position Vector3 lightPos = new Vector3(0, 10, 10); // computing the cos of the angle between the light vector and the normal vector // it will return a value between 0 and 1 that will be used as the intensity of the color float nl1 = ComputeNDotL(v1.WorldCoordinates, v1.Normal, lightPos); float nl2 = ComputeNDotL(v2.WorldCoordinates, v2.Normal, lightPos); float nl3 = ComputeNDotL(v3.WorldCoordinates, v3.Normal, lightPos); var data = new ScanLineData { }; // computing lines' directions float dP1P2, dP1P3; // http://en.wikipedia.org/wiki/Slope // Computing slopes if (p2.Y - p1.Y > 0) { dP1P2 = (p2.X - p1.X) / (p2.Y - p1.Y); } else { dP1P2 = 0; } if (p3.Y - p1.Y > 0) { dP1P3 = (p3.X - p1.X) / (p3.Y - p1.Y); } else { dP1P3 = 0; } // First case where triangles are like that: // P1 // - // -- // - - // - - // - - P2 // - - // - - // - // P3 if (dP1P2 > dP1P3) { for (var y = (int)p1.Y; y <= (int)p3.Y; y++) { data.currentY = y; if (y < p2.Y) { data.ndotla = nl1; data.ndotlb = nl3; data.ndotlc = nl1; data.ndotld = nl2; data.ua = v1.TextureCoordinates.X; data.ub = v3.TextureCoordinates.X; data.uc = v1.TextureCoordinates.X; data.ud = v2.TextureCoordinates.X; data.va = v1.TextureCoordinates.Y; data.vb = v3.TextureCoordinates.Y; data.vc = v1.TextureCoordinates.Y; data.vd = v2.TextureCoordinates.Y; ProcessScanLine(data, v1, v3, v1, v2, color, texture); } else { data.ndotla = nl1; data.ndotlb = nl3; data.ndotlc = nl2; data.ndotld = nl3; data.ua = v1.TextureCoordinates.X; data.ub = v3.TextureCoordinates.X; data.uc = v2.TextureCoordinates.X; data.ud = v3.TextureCoordinates.X; data.va = v1.TextureCoordinates.Y; data.vb = v3.TextureCoordinates.Y; data.vc = v2.TextureCoordinates.Y; data.vd = v3.TextureCoordinates.Y; ProcessScanLine(data, v1, v3, v2, v3, color, texture); } } } // First case where triangles are like that: // P1 // - // -- // - - // - - // P2 - - // - - // - - // - // P3 else { for (var y = (int)p1.Y; y <= (int)p3.Y; y++) { data.currentY = y; if (y < p2.Y) { data.ndotla = nl1; data.ndotlb = nl2; data.ndotlc = nl1; data.ndotld = nl3; data.ua = v1.TextureCoordinates.X; data.ub = v2.TextureCoordinates.X; data.uc = v1.TextureCoordinates.X; data.ud = v3.TextureCoordinates.X; data.va = v1.TextureCoordinates.Y; data.vb = v2.TextureCoordinates.Y; data.vc = v1.TextureCoordinates.Y; data.vd = v3.TextureCoordinates.Y; ProcessScanLine(data, v1, v2, v1, v3, color, texture); } else { data.ndotla = nl2; data.ndotlb = nl3; data.ndotlc = nl1; data.ndotld = nl3; data.ua = v2.TextureCoordinates.X; data.ub = v3.TextureCoordinates.X; data.uc = v1.TextureCoordinates.X; data.ud = v3.TextureCoordinates.X; data.va = v2.TextureCoordinates.Y; data.vb = v3.TextureCoordinates.Y; data.vc = v1.TextureCoordinates.Y; data.vd = v3.TextureCoordinates.Y; ProcessScanLine(data, v2, v3, v1, v3, color, texture); } } } }
// drawing line between 2 points from left to right // papb -> pcpd // pa, pb, pc, pd must then be sorted before void ProcessScanLine(ScanLineData data, Vertex va, Vertex vb, Vertex vc, Vertex vd, Color4 color, Texture texture) { Vector3d pa = va.Coordinates; Vector3d pb = vb.Coordinates; Vector3d pc = vc.Coordinates; Vector3d pd = vd.Coordinates; // Thanks to current Y, we can compute the gradient to compute others values like // the starting X (sx) and ending X (ex) to draw between // if pa.Y == pb.Y or pc.Y == pd.Y, gradient is forced to 1 double gradient1 = pa.Y != pb.Y ? (data.currentY - pa.Y) / (pb.Y - pa.Y) : 1; double gradient2 = pc.Y != pd.Y ? (data.currentY - pc.Y) / (pd.Y - pc.Y) : 1; int sx = (int)Interpolate(pa.X, pb.X, gradient1); int ex = (int)Interpolate(pc.X, pd.X, gradient2); // starting Z & ending Z double z1 = Interpolate(pa.Z, pb.Z, gradient1); double z2 = Interpolate(pc.Z, pd.Z, gradient2); // Interpolating normals on Y double snl = Interpolate(data.ndotla, data.ndotlb, gradient1); double enl = Interpolate(data.ndotlc, data.ndotld, gradient2); // Interpolating texture coordinates on Y double su = Interpolate(data.ua, data.ub, gradient1); double eu = Interpolate(data.uc, data.ud, gradient2); double sv = Interpolate(data.va, data.vb, gradient1); double ev = Interpolate(data.vc, data.vd, gradient2); // drawing a line from left (sx) to right (ex) for (int x = sx; x < ex; x++) { double gradient = (x - sx) / (double)(ex - sx); double z = Interpolate(z1, z2, gradient); //double ndotl = data.ndotla; //flat shader double ndotl = Interpolate(snl, enl, gradient); //for gradient double u = Interpolate(su, eu, gradient); double v = Interpolate(sv, ev, gradient); //// changing the color value using the cosine of the angle //// between the light vector and the normal vector //var c1 = new Color4((float)(color.r * ndotl), // (float)(color.g * ndotl), // (float)(color.b * ndotl), // (float)(1)); //DrawPoint(new Vector3d(x, data.currentY, z), c1); Color4 textureColor; if (texture != null) { textureColor = texture.Map(u, v); } else { textureColor = new Color4(1, 1, 1, 1); } // changing the native color value using the cosine of the angle // between the light vector and the normal vector // and the texture color DrawPoint(new Vector3d(x, data.currentY, z), new Color4( (float)(color.r * ndotl * textureColor.r), (float)(color.g * ndotl * textureColor.g), (float)(color.b * ndotl * textureColor.b), 1 )); } }