Calculating normals

Ruudje · 2003-09-24T09:12:25

Ive got my 3ds loader to work, but I need to calculate the normals of faces and integrate that into my rendring function. here''s some code This function is wrong i think: void file_3ds::calculate_normals(void) { for(int i = 0; i < object->polygons_qty; i++) { object->normal.x = object->vertex[i].x + object->vertex[i+1].x + object->vertex[i+2].x; object->normal[i].y = object->vertex[i].y + object->vertex[i+1].y + object->vertex[i+2].y; object->normal[i].z = object->vertex[i].z + object->vertex[i+1].z + object->vertex[i+2].z; } } This is my rendering function. It uses the values from the above function, but im not sure it uses them correctly. One of these two (or both) are wrong: void file_3ds::render(void) { int l_index; glBegin(GL_TRIANGLES); // glBegin and glEnd delimit the vertices that define a primitive (in our case triangles) for (l_index=0;l_index<object->polygons_qty;l_index++) { //----------------- FIRST VERTEX ----------------- glNormal3f( object->normal[ object->polygon[l_index].a ].x, object->normal[ object->polygon[l_index].a ].y, object->normal[ object->polygon[l_index].a ].z ); // Texture coordinates of the first vertex glTexCoord2f( object->mapcoord[ object->polygon[l_index].a ].u, object->mapcoord[ object->polygon[l_index].a ].v); // Coordinates of the first vertex glVertex3f( object->vertex[ object->polygon[l_index].a ].x, object->vertex[ object->polygon[l_index].a ].y, object->vertex[ object->polygon[l_index].a ].z); //Vertex definition //----------------- SECOND VERTEX ----------------- glNormal3f( object->normal[ object->polygon[l_index].b ].x, object->normal[ object->polygon[l_index].b ].y, object->normal[ object->polygon[l_index].b ].z ); // Texture coordinates of the second vertex glTexCoord2f( object->mapcoord[ object->polygon[l_index].b ].u, object->mapcoord[ object->polygon[l_index].b ].v); // Coordinates of the second vertex glVertex3f( object->vertex[ object->polygon[l_index].b ].x, object->vertex[ object->polygon[l_index].b ].y, object->vertex[ object->polygon[l_index].b ].z); //----------------- THIRD VERTEX ----------------- glNormal3f( object->normal[ object->polygon[l_index].c ].x, object->normal[ object->polygon[l_index].c ].y, object->normal[ object->polygon[l_index].c ].z ); // Texture coordinates of the third vertex glTexCoord2f( object->mapcoord[ object->polygon[l_index].c ].u, object->mapcoord[ object->polygon[l_index].c ].v); // Coordinates of the Third vertex glVertex3f( object->vertex[ object->polygon[l_index].c ].x, object->vertex[ object->polygon[l_index].c ].y, object->vertex[ object->polygon[l_index].c ].z); } glEnd(); } Note: my functions lack good commenting at the moment...

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Started by Ruudje September 22, 2003 07:17 AM

9 comments, last by Ruudje 20 years, 7 months ago

Ruudje

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September 24, 2003 09:12 AM

Well thats what I meant

I did that in school today, and now have it working. All that remains now is adding a texture to the class.

But a question: When experimenting with my new class, rendering a model with 1 light near it, I did notice that some faces got extremely bright, even when I moved the light far away from the object. Is this because there is no texture assigned to it, even though I render the uv-coordinates?

Calculating normals

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Calculating normals

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