Interpolate normals when subdividing

1 files changed, 45 insertions, 16 deletions

diff --git a/src/model.c b/src/model.c
index 5c12f0e..3dc6d46 100644
--- a/src/model.c
+++ b/src/model.c
@@ -343,14 +343,26 @@ static int model_load(ModelContext *ctx, const char *name, RenderContext *render
 					GLfloat v2x, v2y, v2z;
 					GLfloat v3x, v3y, v3z;
 					GLfloat v4x, v4y, v4z;
-					GLfloat nx, ny, nz;
+					GLfloat n1x, n1y, n1z;
+					GLfloat n2x, n2y, n2z;
+					GLfloat n3x, n3y, n3z;
+					GLfloat n4x, n4y, n4z;
 					GLfloat t1x, t1y;
 					GLfloat t2x, t2y;
 					GLfloat t3x, t3y;
 					GLfloat t4x, t4y;
-					nx = normals[3*(num_vertices-1) + 0];
-					ny = normals[3*(num_vertices-1) + 1];
-					nz = normals[3*(num_vertices-1) + 2];
+					n4x = normals[3*(num_vertices-1) + 0];
+					n4y = normals[3*(num_vertices-1) + 1];
+					n4z = normals[3*(num_vertices-1) + 2];
+					n3x = normals[3*(num_vertices-2) + 0];
+					n3y = normals[3*(num_vertices-2) + 1];
+					n3z = normals[3*(num_vertices-2) + 2];
+					n2x = normals[3*(num_vertices-3) + 0];
+					n2y = normals[3*(num_vertices-3) + 1];
+					n2z = normals[3*(num_vertices-3) + 2];
+					n1x = normals[3*(num_vertices-4) + 0];
+					n1y = normals[3*(num_vertices-4) + 1];
+					n1z = normals[3*(num_vertices-4) + 2];
 					v4x = vertices[3*(num_vertices-1) + 0];
 					v4y = vertices[3*(num_vertices-1) + 1];
 					v4z = vertices[3*(num_vertices-1) + 2];
@@ -385,6 +397,10 @@ static int model_load(ModelContext *ctx, const char *name, RenderContext *render
 							GLfloat tl2x, tl2y;
 							GLfloat tl3x, tl3y;
 							GLfloat tl4x, tl4y;
+							GLfloat nl1x, nl1y, nl1z;
+							GLfloat nl2x, nl2y, nl2z;
+							GLfloat nl3x, nl3y, nl3z;
+							GLfloat nl4x, nl4y, nl4z;
 							/* Interpolate vertices */
 							l1x = v1x + u*(v2x-v1x)/x;
 							l1y = v1y + u*(v2y-v1y)/x;
@@ -407,42 +423,55 @@ static int model_load(ModelContext *ctx, const char *name, RenderContext *render
 							tl3y = t1y + (u+1)*(t2y-t1y)/x;
 							tl4x = t4x + (u+1)*(t3x-t4x)/x;
 							tl4y = t4y + (u+1)*(t3y-t4y)/x;
+							/* Interpolate normals */
+							nl1x = n1x + u*(n2x-n1x)/x;
+							nl1y = n1y + u*(n2y-n1y)/x;
+							nl1z = n1z + u*(n2z-n1z)/x;
+							nl2x = n4x + u*(n3x-n4x)/x;
+							nl2y = n4y + u*(n3y-n4y)/x;
+							nl2z = n4z + u*(n3z-n4z)/x;
+							nl3x = n1x + (u+1)*(n2x-n1x)/x;
+							nl3y = n1y + (u+1)*(n2y-n1y)/x;
+							nl3z = n1z + (u+1)*(n2z-n1z)/x;
+							nl4x = n4x + (u+1)*(n3x-n4x)/x;
+							nl4y = n4y + (u+1)*(n3y-n4y)/x;
+							nl4z = n4z + (u+1)*(n3z-n4z)/x;
 							/* Calculate vertices */
 							vertices[3*num_vertices+0] = l1x + v*(l2x-l1x)/y;
 							vertices[3*num_vertices+1] = l1y + v*(l2y-l1y)/y;
 							vertices[3*num_vertices+2] = l1z + v*(l2z-l1z)/y;
 							texcoords[2*num_vertices+0] = tl1x + v*(tl2x-tl1x)/y;
 							texcoords[2*num_vertices+1] = tl1y + v*(tl2y-tl1y)/y;
-							normals[3*num_vertices+0] = nx;
-							normals[3*num_vertices+1] = ny;
-							normals[3*num_vertices+2] = nz;
+							normals[3*num_vertices+0] = nl1x + v*(nl2x-nl1x)/y;
+							normals[3*num_vertices+1] = nl1y + v*(nl2y-nl1y)/y;
+							normals[3*num_vertices+2] = nl1z + v*(nl2z-nl1z)/y;
 							num_vertices++;
 							vertices[3*num_vertices+0] = l3x + v*(l4x-l3x)/y;
 							vertices[3*num_vertices+1] = l3y + v*(l4y-l3y)/y;
 							vertices[3*num_vertices+2] = l3z + v*(l4z-l3z)/y;
 							texcoords[2*num_vertices+0] = tl3x + v*(tl4x-tl3x)/y;
 							texcoords[2*num_vertices+1] = tl3y + v*(tl4y-tl3y)/y;
-							normals[3*num_vertices+0] = nx;
-							normals[3*num_vertices+1] = ny;
-							normals[3*num_vertices+2] = nz;
+							normals[3*num_vertices+0] = nl3x + v*(nl4x-nl3x)/y;
+							normals[3*num_vertices+1] = nl3y + v*(nl4y-nl3y)/y;
+							normals[3*num_vertices+2] = nl3z + v*(nl4z-nl3z)/y;
 							num_vertices++;
 							vertices[3*num_vertices+0] = l3x + (v+1)*(l4x-l3x)/y;
 							vertices[3*num_vertices+1] = l3y + (v+1)*(l4y-l3y)/y;
 							vertices[3*num_vertices+2] = l3z + (v+1)*(l4z-l3z)/y;
 							texcoords[2*num_vertices+0] = tl3x + (v+1)*(tl4x-tl3x)/y;
 							texcoords[2*num_vertices+1] = tl3y + (v+1)*(tl4y-tl3y)/y;
-							normals[3*num_vertices+0] = nx;
-							normals[3*num_vertices+1] = ny;
-							normals[3*num_vertices+2] = nz;
+							normals[3*num_vertices+0] = nl3x + (v+1)*(nl4x-nl3x)/y;
+							normals[3*num_vertices+1] = nl3y + (v+1)*(nl4y-nl3y)/y;
+							normals[3*num_vertices+2] = nl3z + (v+1)*(nl4z-nl3z)/y;
 							num_vertices++;
 							vertices[3*num_vertices+0] = l1x + (v+1)*(l2x-l1x)/y;
 							vertices[3*num_vertices+1] = l1y + (v+1)*(l2y-l1y)/y;
 							vertices[3*num_vertices+2] = l1z + (v+1)*(l2z-l1z)/y;
 							texcoords[2*num_vertices+0] = tl1x + (v+1)*(tl2x-tl1x)/y;
 							texcoords[2*num_vertices+1] = tl1y + (v+1)*(tl2y-tl1y)/y;
-							normals[3*num_vertices+0] = nx;
-							normals[3*num_vertices+1] = ny;
-							normals[3*num_vertices+2] = nz;
+							normals[3*num_vertices+0] = n1x + (v+1)*(nl2x-nl1x)/y;
+							normals[3*num_vertices+1] = n1y + (v+1)*(nl2y-nl1y)/y;
+							normals[3*num_vertices+2] = n1z + (v+1)*(nl2z-nl1z)/y;
 							num_vertices++;
 						}
 					}