GLUSvoid GLUSAPIENTRY glusQuaternionRotateRzf(GLUSfloat quaternion[4], const GLUSfloat angle)
{
GLUSfloat halfAngleRadian = glusMathDegToRadf(angle) * 0.5f;
quaternion[0] = 0.0f;
quaternion[1] = 0.0f;
quaternion[2] = sinf(halfAngleRadian);
quaternion[3] = cosf(halfAngleRadian);
}
GLUSvoid GLUSAPIENTRY glusQuaternionRotatef(GLUSfloat quaternion[4], const GLUSfloat angle, const GLUSfloat x, const GLUSfloat y, const GLUSfloat z)
{
GLUSfloat halfAngleRadian = glusMathDegToRadf(angle) * 0.5f;
GLUSfloat s = sinf(halfAngleRadian);
GLUSfloat normalized[3] = { x, y, z };
glusVector3Normalizef(normalized);
quaternion[0] = normalized[0] * s;
quaternion[1] = normalized[1] * s;
quaternion[2] = normalized[2] * s;
quaternion[3] = cosf(halfAngleRadian);
}
GLUSboolean update(GLUSfloat time)
{
static GLfloat angle = 0.0f;
GLfloat angleRadians;
GLfloat viewProjectionMatrix[16];
GLfloat viewMatrix[16];
GLfloat modelMatrix[16];
GLfloat normalMatrix[9];
GLfloat camera[4] = {0.0, 0.0, 0.0, 1.0};
angleRadians = glusMathDegToRadf(angle);
camera[0] = g_circleRadius * -sinf(angleRadians);
camera[2] = g_circleRadius * cosf(angleRadians);
// Circle with the camera around the origin by looking at it.
glusMatrix4x4LookAtf(viewMatrix, camera[0], 0.0f, camera[2], 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f);
glusMatrix4x4Multiplyf(viewProjectionMatrix, g_projectionMatrix, viewMatrix);
glusMatrix4x4Identityf(modelMatrix);
glusMatrix4x4Translatef(modelMatrix, 0.0f, -0.5f, 0.0f);
glusMatrix4x4RotateRxf(modelMatrix, 45.0f);
glusMatrix4x4ExtractMatrix3x3f(normalMatrix, modelMatrix);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//
// First render the background.
glUseProgram(g_programBackground.program);
glUniformMatrix4fv(g_viewProjectionMatrixBackgroundLocation, 1, GL_FALSE, viewProjectionMatrix);
glUniformMatrix4fv(g_modelMatrixBackgroundLocation, 1, GL_FALSE, modelMatrix);
glBindVertexArray(g_vaoBackground);
glFrontFace(GL_CW);
glDrawElements(GL_TRIANGLES, g_numberIndicesBackground, GL_UNSIGNED_INT, 0);
// Now render the sphere.
glUseProgram(g_program.program);
glUniformMatrix4fv(g_viewProjectionMatrixLocation, 1, GL_FALSE, viewProjectionMatrix);
glUniformMatrix4fv(g_modelMatrixLocation, 1, GL_FALSE, modelMatrix);
glUniformMatrix3fv(g_normalMatrixLocation, 1, GL_FALSE, normalMatrix);
glUniform4fv(g_cameraLocation, 1, camera);
glBindVertexArray(g_vao);
glFrontFace(GL_CCW);
glDrawElements(GL_TRIANGLES, g_numberIndicesSphere, GL_UNSIGNED_INT, 0);
// Increase the angle 30 degree per second.
angle += 30.0f * time;
return GLUS_TRUE;
}