/**
* Create a gear wheel.
*
* @param inner_radius radius of hole at center
* @param outer_radius radius at center of teeth
* @param width width of gear
* @param teeth number of teeth
* @param tooth_depth depth of tooth
*
* @return pointer to the constructed struct gear
*/
static struct gear *
create_gear (GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
GLint teeth, GLfloat tooth_depth)
{
GLfloat r0, r1, r2;
GLfloat da;
GearVertex *v;
struct gear *gear;
double s[5], c[5];
GLfloat normal[3];
int cur_strip = 0;
int i;
/* Allocate memory for the gear */
gear = malloc (sizeof *gear);
if (gear == NULL)
return NULL;
/* Calculate the radii used in the gear */
r0 = inner_radius;
r1 = outer_radius - tooth_depth / 2.0;
r2 = outer_radius + tooth_depth / 2.0;
da = 2.0 * M_PI / teeth / 4.0;
/* Allocate memory for the triangle strip information */
gear->nstrips = STRIPS_PER_TOOTH * teeth;
gear->strips = calloc (gear->nstrips, sizeof (*gear->strips));
/* Allocate memory for the vertices */
gear->vertices = calloc (VERTICES_PER_TOOTH * teeth, sizeof(*gear->vertices));
v = gear->vertices;
for (i = 0; i < teeth; i++) {
/* Calculate needed sin/cos for varius angles */
sincos (i * 2.0 * M_PI / teeth, &s[0], &c[0]);
sincos (i * 2.0 * M_PI / teeth + da, &s[1], &c[1]);
sincos (i * 2.0 * M_PI / teeth + da * 2, &s[2], &c[2]);
sincos (i * 2.0 * M_PI / teeth + da * 3, &s[3], &c[3]);
sincos (i * 2.0 * M_PI / teeth + da * 4, &s[4], &c[4]);
/* A set of macros for making the creation of the gears easier */
#define GEAR_POINT(r, da) { (r) * c[(da)], (r) * s[(da)] }
#define SET_NORMAL(x, y, z) do { \
normal[0] = (x); normal[1] = (y); normal[2] = (z); \
} while(0)
#define GEAR_VERT(v, point, sign) vert((v), p[(point)].x, p[(point)].y, (sign) * width * 0.5, normal)
#define START_STRIP do { \
gear->strips[cur_strip].first = v - gear->vertices; \
} while(0);
#define END_STRIP do { \
int _tmp = (v - gear->vertices); \
gear->strips[cur_strip].count = _tmp - gear->strips[cur_strip].first; \
cur_strip++; \
} while (0)
#define QUAD_WITH_NORMAL(p1, p2) do { \
SET_NORMAL((p[(p1)].y - p[(p2)].y), -(p[(p1)].x - p[(p2)].x), 0); \
v = GEAR_VERT(v, (p1), -1); \
v = GEAR_VERT(v, (p1), 1); \
v = GEAR_VERT(v, (p2), -1); \
v = GEAR_VERT(v, (p2), 1); \
} while(0)
{
struct point {
GLfloat x;
GLfloat y;
};
/* Create the 7 points (only x,y coords) used to draw a tooth */
struct point p[7] = {
GEAR_POINT (r2, 1), // 0
GEAR_POINT (r2, 2), // 1
GEAR_POINT (r1, 0), // 2
GEAR_POINT (r1, 3), // 3
GEAR_POINT (r0, 0), // 4
GEAR_POINT (r1, 4), // 5
GEAR_POINT (r0, 4), // 6
};
/* Front face */
START_STRIP;
SET_NORMAL (0, 0, 1.0);
v = GEAR_VERT (v, 0, +1);
v = GEAR_VERT (v, 1, +1);
v = GEAR_VERT (v, 2, +1);
v = GEAR_VERT (v, 3, +1);
v = GEAR_VERT (v, 4, +1);
v = GEAR_VERT (v, 5, +1);
v = GEAR_VERT (v, 6, +1);
END_STRIP;
/* Inner face */
START_STRIP;
QUAD_WITH_NORMAL (4, 6);
END_STRIP;
/* Back face */
START_STRIP;
SET_NORMAL (0, 0, -1.0);
v = GEAR_VERT (v, 6, -1);
v = GEAR_VERT (v, 5, -1);
v = GEAR_VERT (v, 4, -1);
v = GEAR_VERT (v, 3, -1);
v = GEAR_VERT (v, 2, -1);
v = GEAR_VERT (v, 1, -1);
v = GEAR_VERT (v, 0, -1);
END_STRIP;
/* Outer face */
START_STRIP;
QUAD_WITH_NORMAL (0, 2);
END_STRIP;
START_STRIP;
QUAD_WITH_NORMAL (1, 0);
END_STRIP;
START_STRIP;
QUAD_WITH_NORMAL (3, 1);
END_STRIP;
START_STRIP;
QUAD_WITH_NORMAL (5, 3);
END_STRIP;
}
}
gear->nvertices = (v - gear->vertices);
/* Store the vertices in a vertex buffer object (VBO) */
glGenBuffers (1, &gear->vbo);
glBindBuffer (GL_ARRAY_BUFFER, gear->vbo);
glBufferData (GL_ARRAY_BUFFER, gear->nvertices * sizeof(GearVertex),
gear->vertices, GL_STATIC_DRAW);
return gear;
}
/**
* Create a gear wheel.
*
* @param inner_radius radius of hole at center
* @param outer_radius radius at center of teeth
* @param width width of gear
* @param teeth number of teeth
* @param tooth_depth depth of tooth
*
* @return pointer to the constructed struct gear
*/
static struct gear *
create_gear(struct pipe_screen *screen, struct pipe_context *pipe, float inner_radius, float outer_radius, float width,
int teeth, float tooth_depth)
{
float r0, r1, r2;
float da;
GearVertex *v;
struct gear *gear;
double s[5], c[5];
float normal[3];
int cur_strip = 0;
int i;
/* Allocate memory for the gear */
gear = malloc(sizeof *gear);
if (gear == NULL)
return NULL;
/* Calculate the radii used in the gear */
r0 = inner_radius;
r1 = outer_radius - tooth_depth / 2.0;
r2 = outer_radius + tooth_depth / 2.0;
da = 2.0 * M_PI / teeth / 4.0;
/* Allocate memory for the triangle strip information */
gear->nstrips = STRIPS_PER_TOOTH * teeth;
gear->strips = calloc(gear->nstrips, sizeof (*gear->strips));
/* Allocate memory for the vertices */
gear->vertices = calloc(VERTICES_PER_TOOTH * teeth, sizeof(*gear->vertices));
v = gear->vertices;
for (i = 0; i < teeth; i++) {
/* Calculate needed sin/cos for varius angles */
sincos_(i * 2.0 * M_PI / teeth, &s[0], &c[0]);
sincos_(i * 2.0 * M_PI / teeth + da, &s[1], &c[1]);
sincos_(i * 2.0 * M_PI / teeth + da * 2, &s[2], &c[2]);
sincos_(i * 2.0 * M_PI / teeth + da * 3, &s[3], &c[3]);
sincos_(i * 2.0 * M_PI / teeth + da * 4, &s[4], &c[4]);
/* A set of macros for making the creation of the gears easier */
#define GEAR_POINT(r, da) { (r) * c[(da)], (r) * s[(da)] }
#define SET_NORMAL(x, y, z) do { \
normal[0] = (x); normal[1] = (y); normal[2] = (z); \
} while(0)
#define GEAR_VERT(v, point, sign) vert((v), p[(point)].x, p[(point)].y, (sign) * width * 0.5, normal)
#define START_STRIP do { \
gear->strips[cur_strip].first = v - gear->vertices; \
} while(0);
#define END_STRIP do { \
int _tmp = (v - gear->vertices); \
gear->strips[cur_strip].count = _tmp - gear->strips[cur_strip].first; \
cur_strip++; \
} while (0)
#define QUAD_WITH_NORMAL(p1, p2) do { \
SET_NORMAL((p[(p1)].y - p[(p2)].y), -(p[(p1)].x - p[(p2)].x), 0); \
v = GEAR_VERT(v, (p1), -1); \
v = GEAR_VERT(v, (p1), 1); \
v = GEAR_VERT(v, (p2), -1); \
v = GEAR_VERT(v, (p2), 1); \
} while(0)
struct point {
float x;
float y;
};
/* Create the 7 points (only x,y coords) used to draw a tooth */
struct point p[7] = {
GEAR_POINT(r2, 1), // 0
GEAR_POINT(r2, 2), // 1
GEAR_POINT(r1, 0), // 2
GEAR_POINT(r1, 3), // 3
GEAR_POINT(r0, 0), // 4
GEAR_POINT(r1, 4), // 5
GEAR_POINT(r0, 4), // 6
};
/* Front face */
START_STRIP;
SET_NORMAL(0, 0, 1.0);
v = GEAR_VERT(v, 0, +1);
v = GEAR_VERT(v, 1, +1);
v = GEAR_VERT(v, 2, +1);
v = GEAR_VERT(v, 3, +1);
v = GEAR_VERT(v, 4, +1);
v = GEAR_VERT(v, 5, +1);
v = GEAR_VERT(v, 6, +1);
END_STRIP;
/* Inner face */
START_STRIP;
QUAD_WITH_NORMAL(4, 6);
END_STRIP;
/* Back face */
START_STRIP;
SET_NORMAL(0, 0, -1.0);
v = GEAR_VERT(v, 6, -1);
v = GEAR_VERT(v, 5, -1);
v = GEAR_VERT(v, 4, -1);
v = GEAR_VERT(v, 3, -1);
v = GEAR_VERT(v, 2, -1);
v = GEAR_VERT(v, 1, -1);
v = GEAR_VERT(v, 0, -1);
END_STRIP;
/* Outer face */
START_STRIP;
QUAD_WITH_NORMAL(0, 2);
END_STRIP;
START_STRIP;
QUAD_WITH_NORMAL(1, 0);
END_STRIP;
START_STRIP;
QUAD_WITH_NORMAL(3, 1);
END_STRIP;
START_STRIP;
QUAD_WITH_NORMAL(5, 3);
END_STRIP;
}
gear->nvertices = (v - gear->vertices);
/* element layout */
struct pipe_vertex_element pipe_vertex_elements[] = {
{ /* positions */
.src_offset = 0x0,
.instance_divisor = 0,
.vertex_buffer_index = 0,
.src_format = PIPE_FORMAT_R32G32B32_FLOAT
},
{ /* normals */
.src_offset = 0xc,
