Я пытаюсь создать среднюю половину сферы. В основном для создания сферы даются номера стеков и номеров срезов, и есть две переменные phi
(для срезов) и theta
(для стеков), отвечающие за прогресс. И процесс делится на создание нижней крышки, корпуса и верхней крышки (как показано ниже). Чтобы достичь средней половины ( theta
в среднем 50%, как показано ниже), нам нужно опустить колпачки и как-то модифицировать корпус. Я играл с номерами стеков ( 1/4*stackNumbers to 3/4*stackNumbers
), но не дал желаемого результата.
Как мне изменить генерацию сферы для достижения средней половины ( pi/4 <theta <pi*3/4
)? Моя общая проблема заключается в том, как разделить сферу на 3 части: верхние 25%, средние 50% и нижние 25%?
Вот популярный код для программной генерации сферы:
private void generateSphere(int stackNumber, int sliceNumber, boolean facingOut) {
int capVertexNumber = 3 * sliceNumber;
int bodyVertexNumber = 4 * sliceNumber * (stackNumber - 2);
int vertexNumber = (2 * capVertexNumber) + bodyVertexNumber;
int triangleNumber = (2 * capVertexNumber) + (6 * sliceNumber * (stackNumber - 2));
vertices = new float[3 * vertexNumber];
normals = new float[3 * vertexNumber];
texCoords = new float[2 * vertexNumber];
indices = new char[triangleNumber];
// bottom cap
// createCap(stackNumber, sliceNumber, false, facingOut);
// body
createBody(stackNumber, sliceNumber, facingOut);
// top cap
createCap(stackNumber, sliceNumber, true, facingOut);
}
private void createCap(int stackNumber, int sliceNumber, boolean top, boolean facingOut) {
float stackPercentage0;
float stackPercentage1;
if (!top) {
stackPercentage0 = ((float) (stackNumber - 1) / stackNumber);
stackPercentage1 = 1.0f;
} else {
stackPercentage0 = (1.0f / stackNumber);
stackPercentage1 = 0.0f;
}
float t0 = stackPercentage0;
float t1 = stackPercentage1;
double theta0 = stackPercentage0 * Math.PI;
double theta1 = stackPercentage1 * Math.PI;
double cosTheta0 = Math.cos(theta0);
double sinTheta0 = Math.sin(theta0);
double cosTheta1 = Math.cos(theta1);
double sinTheta1 = Math.sin(theta1);
for (int slice = 0; slice < sliceNumber; slice++) {
float slicePercentage0 = ((float) (slice) / sliceNumber);
float slicePercentage1 = ((float) (slice + 1) / sliceNumber);
double phi0 = slicePercentage0 * 2.0 * Math.PI;
double phi1 = slicePercentage1 * 2.0 * Math.PI;
float s0, s1;
if (facingOut) {
s0 = 1 - slicePercentage0;
s1 = 1 - slicePercentage1;
} else {
s0 = slicePercentage0;
s1 = slicePercentage1;
}
float s2 = (s0 + s1) / 2.0f;
double cosPhi0 = Math.cos(phi0);
double sinPhi0 = Math.sin(phi0);
double cosPhi1 = Math.cos(phi1);
double sinPhi1 = Math.sin(phi1);
float x0 = (float) (sinTheta0 * cosPhi0);
float y0 = (float) cosTheta0;
float z0 = (float) (sinTheta0 * sinPhi0);
float x1 = (float) (sinTheta0 * cosPhi1);
float y1 = (float) cosTheta0;
float z1 = (float) (sinTheta0 * sinPhi1);
float x2 = (float) (sinTheta1 * cosPhi0);
float y2 = (float) cosTheta1;
float z2 = (float) (sinTheta1 * sinPhi0);
vertices[vertexCount + 0] = x0;
vertices[vertexCount + 1] = y0;
vertices[vertexCount + 2] = z0;
vertices[vertexCount + 3] = x1;
vertices[vertexCount + 4] = y1;
vertices[vertexCount + 5] = z1;
vertices[vertexCount + 6] = x2;
vertices[vertexCount + 7] = y2;
vertices[vertexCount + 8] = z2;
if (facingOut) {
normals[vertexCount + 0] = x0;
normals[vertexCount + 1] = y0;
normals[vertexCount + 2] = z0;
normals[vertexCount + 3] = x1;
normals[vertexCount + 4] = y1;
normals[vertexCount + 5] = z1;
normals[vertexCount + 6] = x2;
normals[vertexCount + 7] = y2;
normals[vertexCount + 8] = z2;
} else {
normals[vertexCount + 0] = -x0;
normals[vertexCount + 1] = -y0;
normals[vertexCount + 2] = -z0;
normals[vertexCount + 3] = -x1;
normals[vertexCount + 4] = -y1;
normals[vertexCount + 5] = -z1;
normals[vertexCount + 6] = -x2;
normals[vertexCount + 7] = -y2;
normals[vertexCount + 8] = -z2;
}
texCoords[texCoordCount + 0] = s0;
texCoords[texCoordCount + 1] = t0;
texCoords[texCoordCount + 2] = s1;
texCoords[texCoordCount + 3] = t0;
texCoords[texCoordCount + 4] = s2;
texCoords[texCoordCount + 5] = t1;
if ((facingOut && top) || (!facingOut && !top)) {
indices[indexCount + 0] = (char) (triangleCount + 1);
indices[indexCount + 1] = (char) (triangleCount + 0);
indices[indexCount + 2] = (char) (triangleCount + 2);
} else {
indices[indexCount + 0] = (char) (triangleCount + 0);
indices[indexCount + 1] = (char) (triangleCount + 1);
indices[indexCount + 2] = (char) (triangleCount + 2);
}
vertexCount += 9;
texCoordCount += 6;
indexCount += 3;
triangleCount += 3;
}
}
private void createBody(int stackNumber, int sliceNumber, boolean facingOut) {
for (int stack = 1; stack < stackNumber - 1; stack++) {
float stackPercentage0 = ((float) (stack) / stackNumber);
float stackPercentage1 = ((float) (stack + 1) / stackNumber);
float t0 = stackPercentage0;
float t1 = stackPercentage1;
double theta0 = stackPercentage0 * Math.PI;
double theta1 = stackPercentage1 * Math.PI;
double cosTheta0 = Math.cos(theta0);
double sinTheta0 = Math.sin(theta0);
double cosTheta1 = Math.cos(theta1);
double sinTheta1 = Math.sin(theta1);
for (int slice = 0; slice < sliceNumber; slice++) {
float slicePercentage0 = ((float) (slice) / sliceNumber);
float slicePercentage1 = ((float) (slice + 1) / sliceNumber);
double phi0 = slicePercentage0 * 2.0 * Math.PI;
double phi1 = slicePercentage1 * 2.0 * Math.PI;
float s0, s1;
if (facingOut) {
s0 = 1.0f - slicePercentage0;
s1 = 1.0f - slicePercentage1;
} else {
s0 = slicePercentage0;
s1 = slicePercentage1;
}
double cosPhi0 = Math.cos(phi0);
double sinPhi0 = Math.sin(phi0);
double cosPhi1 = Math.cos(phi1);
double sinPhi1 = Math.sin(phi1);
float x0 = (float) (sinTheta0 * cosPhi0);
float y0 = (float) cosTheta0;
float z0 = (float) (sinTheta0 * sinPhi0);
float x1 = (float) (sinTheta0 * cosPhi1);
float y1 = (float) cosTheta0;
float z1 = (float) (sinTheta0 * sinPhi1);
float x2 = (float) (sinTheta1 * cosPhi0);
float y2 = (float) cosTheta1;
float z2 = (float) (sinTheta1 * sinPhi0);
float x3 = (float) (sinTheta1 * cosPhi1);
float y3 = (float) cosTheta1;
float z3 = (float) (sinTheta1 * sinPhi1);
vertices[vertexCount + 0] = x0;
vertices[vertexCount + 1] = y0;
vertices[vertexCount + 2] = z0;
vertices[vertexCount + 3] = x1;
vertices[vertexCount + 4] = y1;
vertices[vertexCount + 5] = z1;
vertices[vertexCount + 6] = x2;
vertices[vertexCount + 7] = y2;
vertices[vertexCount + 8] = z2;
vertices[vertexCount + 9] = x3;
vertices[vertexCount + 10] = y3;
vertices[vertexCount + 11] = z3;
if (facingOut) {
normals[vertexCount + 0] = x0;
normals[vertexCount + 1] = y0;
normals[vertexCount + 2] = z0;
normals[vertexCount + 3] = x1;
normals[vertexCount + 4] = y1;
normals[vertexCount + 5] = z1;
normals[vertexCount + 6] = x2;
normals[vertexCount + 7] = y2;
normals[vertexCount + 8] = z2;
normals[vertexCount + 9] = x3;
normals[vertexCount + 10] = y3;
normals[vertexCount + 11] = z3;
} else {
normals[vertexCount + 0] = -x0;
normals[vertexCount + 1] = -y0;
normals[vertexCount + 2] = -z0;
normals[vertexCount + 3] = -x1;
normals[vertexCount + 4] = -y1;
normals[vertexCount + 5] = -z1;
normals[vertexCount + 6] = -x2;
normals[vertexCount + 7] = -y2;
normals[vertexCount + 8] = -z2;
normals[vertexCount + 9] = -x3;
normals[vertexCount + 10] = -y3;
normals[vertexCount + 11] = -z3;
}
texCoords[texCoordCount + 0] = s0;
texCoords[texCoordCount + 1] = t0;
texCoords[texCoordCount + 2] = s1;
texCoords[texCoordCount + 3] = t0;
texCoords[texCoordCount + 4] = s0;
texCoords[texCoordCount + 5] = t1;
texCoords[texCoordCount + 6] = s1;
texCoords[texCoordCount + 7] = t1;
// one quad looking from outside toward center
//
// @formatter:off
//
// s1 --> s0
//
// t0 1-----0
// | | |
// v | |
// t1 3-----2
//
// @formatter:on
//
// Note that tex_coord t increase from top to bottom because the
// texture image is loaded upside down.
if (facingOut) {
indices[indexCount + 0] = (char) (triangleCount + 0);
indices[indexCount + 1] = (char) (triangleCount + 1);
indices[indexCount + 2] = (char) (triangleCount + 2);
indices[indexCount + 3] = (char) (triangleCount + 2);
indices[indexCount + 4] = (char) (triangleCount + 1);
indices[indexCount + 5] = (char) (triangleCount + 3);
} else {
indices[indexCount + 0] = (char) (triangleCount + 0);
indices[indexCount + 1] = (char) (triangleCount + 2);
indices[indexCount + 2] = (char) (triangleCount + 1);
indices[indexCount + 3] = (char) (triangleCount + 2);
indices[indexCount + 4] = (char) (triangleCount + 3);
indices[indexCount + 5] = (char) (triangleCount + 1);
}
vertexCount += 12;
texCoordCount += 8;
indexCount += 6;
triangleCount += 4;
}
}
}