CODEWITHSUNDEEP
javaopengllwjgl
Mohamad_Hn
Mohamad_Hn

Reputation: 95

texturing a sphere using LWJGL opengl?

I want to draw a sphere and texture it,i draw it by triangles and when i am trying to texture it some triangles aren't covered

i am using this function to generate the Coordinates 

public void createSolidSphere()
    {
        float R = (float) (1./(float)(rings-1));
        float S = (float) (1./(float)(sectors-1));
        int r, s;
        int texCoordsIndex = -1;
        int verticesIndex = -1;
        int normalsIndex = -1;
        int indicesIndex = -1;
        for(r = 0; r < rings; r++) for(s = 0; s < sectors; s++) {
            float y = (float)Math.sin( -Math.PI/2 + Math.PI * r * R );
            float x = (float)Math.cos(2*Math.PI * s * S) * (float)Math.sin( Math.PI * r * R );
            float z = (float)Math.sin(2*Math.PI * s * S) * (float)Math.sin( Math.PI * r * R );

            texcoords[++texCoordsIndex] = s*S;
            texcoords[++texCoordsIndex] = r*R;

            vertices[++verticesIndex] = x * radius;
            vertices[++verticesIndex] = y * radius;
            vertices[++verticesIndex] = z * radius;

            normals[++normalsIndex] = x;
            normals[++normalsIndex] = y;
            normals[++normalsIndex] = z;
        }
        for(r = 0; r < rings; r++) for(s = 0; s < sectors; s++) {


            indices[++indicesIndex] = r * sectors + (s+1);
            indices[++indicesIndex] = (r+1) * sectors + (s+1);
            indices[++indicesIndex] = (r+1) * sectors + s;
        }
    }

Upvotes: 1

Views: 167

Answers (1)

Rabbid76
Rabbid76

Reputation: 210909

You've to draw quads rather than triangles. A quad can be formed by 2 triangles.
Each quad consist of 4 points:

0: r * sectors + (s+1)
1: (r+1) * sectors + (s+1)
2: (r+1) * sectors + s
3: r * sectors + s

This 4 points can be arranged to 2 triangles:

    2           1
     + +-------+
     | \ \     |
     |   \ \   |
     |     \ \ |
     +------+  +
    3           0

You've to add 6 indices for each quad rather than 3: 

for(r = 0; r < rings; r++) for(s = 0; s < sectors; s++) {

    // triangle 1
    indices[++indicesIndex] = r * sectors + (s+1);
    indices[++indicesIndex] = (r+1) * sectors + (s+1);
    indices[++indicesIndex] = (r+1) * sectors + s;

    // triangle 2
    indices[++indicesIndex] = r * sectors + (s+1);
    indices[++indicesIndex] = (r+1) * sectors + s;
    indices[++indicesIndex] = r * sectors + s+;
}

Upvotes: 1

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