/*
* Fragment shader for surface color based on surface normals.
*/
static void fragment_shader_color(int y, int x, struct fragment_input *input, struct uniform_variables *vars){
if(input->frag_coord[VAR_Z] >= read_depth(y, x)){
return;
}
vec3 object_normal;
object_normal[VAR_X] = input->attributes[0] / input->frag_coord[VAR_W];
object_normal[VAR_Y] = input->attributes[1] / input->frag_coord[VAR_W];
object_normal[VAR_Z] = input->attributes[2] / input->frag_coord[VAR_W];
normalize_vec3(object_normal);
if(input->front_facing == ER_FALSE){
object_normal[VAR_X] = -object_normal[VAR_X];
object_normal[VAR_Y] = -object_normal[VAR_Y];
object_normal[VAR_Z] = -object_normal[VAR_Z];
}
float red, green, blue;
red = (object_normal[VAR_X] * 0.5f + 0.5f);
red = clamp(red, 0.0f, 1.0f);
green = (object_normal[VAR_Y] * 0.5f + 0.5f);
green = clamp(green, 0.0f, 1.0f);
blue = (object_normal[VAR_X] * 0.5f + 0.5f);
blue = clamp(blue, 0.0f, 1.0f);
write_color(y, x, red, green, blue, 1.0f);
write_depth(y, x, input->frag_coord[VAR_Z]);
}
/*
* Fragment shader for axis and arrows.
*/
static void fragment_shader_axis(int y, int x, struct fragment_input *input, struct uniform_variables *vars){
if(input->frag_coord[VAR_Z] >= read_depth(y, x)){
return;
}
write_color(y, x, input->attributes[0], input->attributes[1], input->attributes[2], 1.0f);
write_depth(y, x, input->frag_coord[VAR_Z]);
}
boost::optional<Eigen::Vector3f> read_depth_and_unproject(const Vector2i &screen_pos,
const Eigen::Matrix4f &model,
const Eigen::Matrix4f &proj,
const Vector2i &viewportSize, bool flipY) {
float z = read_depth(screen_pos, flipY, viewportSize.y());
if (z == 1.0f)
return boost::none;
return unproject(Eigen::Vector3f{(float)screen_pos.x(), (float)screen_pos.y(), z}, model, proj, viewportSize, flipY);
}
static void
find_actual_mrd(GLdouble *next_to_near, GLdouble *next_to_far,
GLdouble *actual_mrd_near, GLdouble *actual_mrd_far)
{
/* Here we use polygon offset to determine the implementation's actual
* MRD.
*/
double base_depth;
glDepthFunc(GL_ALWAYS);
/* Draw a quad far away from the eye and read the depth at its
* center:
*/
glDisable(GL_POLYGON_OFFSET_FILL);
draw_quad_at_distance(*next_to_far);
base_depth = read_depth(piglit_width/2, piglit_height/2);
/* Now draw a quad that's one MRD closer to the eye: */
glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonOffset(0.0, -1.0);
draw_quad_at_distance(*next_to_far);
/* The difference between the depths of the two quads is the value the
* implementation is actually using for one MRD:
*/
*actual_mrd_far = base_depth
- read_depth(piglit_width/2, piglit_height/2);
/* Repeat the process for a quad close to the eye: */
glDisable(GL_POLYGON_OFFSET_FILL);
draw_quad_at_distance(*next_to_near);
base_depth = read_depth(piglit_width / 2, piglit_height / 2);
glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonOffset(0.0, 1.0); /* 1 MRD further away */
draw_quad_at_distance(*next_to_near);
*actual_mrd_near = read_depth(piglit_width / 2, piglit_height / 2)
- base_depth;
}
/*
* Fragment shader for surface lighting. One directional light source, phong shading.
*/
static void fragment_shader_light(int y, int x, struct fragment_input *input, struct uniform_variables *vars){
if(input->frag_coord[VAR_Z] >= read_depth(y, x)){
return;
}
float *light_dir = &(vars->uniform_float[0]);
vec3 eye_normal, object_normal;
object_normal[VAR_X] = input->attributes[0] / input->frag_coord[VAR_W];
object_normal[VAR_Y] = input->attributes[1] / input->frag_coord[VAR_W];
object_normal[VAR_Z] = input->attributes[2] / input->frag_coord[VAR_W];
eye_normal[VAR_X] = input->attributes[3] / input->frag_coord[VAR_W];
eye_normal[VAR_Y] = input->attributes[4] / input->frag_coord[VAR_W];
eye_normal[VAR_Z] = input->attributes[5] / input->frag_coord[VAR_W];
normalize_vec3(eye_normal);
normalize_vec3(object_normal);
if(input->front_facing == ER_FALSE){
eye_normal[VAR_X] = -eye_normal[VAR_X];
eye_normal[VAR_Y] = -eye_normal[VAR_Y];
eye_normal[VAR_Z] = -eye_normal[VAR_Z];
object_normal[VAR_X] = -object_normal[VAR_X];
object_normal[VAR_Y] = -object_normal[VAR_Y];
object_normal[VAR_Z] = -object_normal[VAR_Z];
}
float diffuse_term = max(0.0f, dot_vec3(light_dir, eye_normal) );
float specular_term = 0.0f;
vec3 view_vector;
vec3 half_vector;
view_vector[VAR_X] = 0.0f;
view_vector[VAR_Y] = 0.0f;
view_vector[VAR_Z] = 1.0f;
if(diffuse_term > 0.0f){
half_vector[VAR_X] = light_dir[VAR_X] + view_vector[VAR_X];
half_vector[VAR_Y] = light_dir[VAR_Y] + view_vector[VAR_Y];
half_vector[VAR_Z] = light_dir[VAR_Z] + view_vector[VAR_Z];
normalize_vec3(half_vector);
specular_term = pow( max(0.0f, dot_vec3(half_vector, eye_normal)), 50.0f );
}
float red, green, blue, light_intensity;
light_intensity = 0.6f * diffuse_term + 0.4f * specular_term;
red = (object_normal[VAR_X] * 0.5f + 0.5f) * light_intensity;
red = clamp(red, 0.0f, 1.0f);
green = (object_normal[VAR_Y] * 0.5f + 0.5f) * light_intensity;
green = clamp(green, 0.0f, 1.0f);
blue = (object_normal[VAR_Z] * 0.5f + 0.5f) * light_intensity;
blue = clamp(blue, 0.0f, 1.0f);
write_color(y, x, red, green, blue, 1.0f);
write_depth(y, x, input->frag_coord[VAR_Z]);
}
/*
* Fragment shader for texture mapped cube.
*/
static void fs_cube(int y, int x, struct fragment_input *input, struct uniform_variables *vars){
if(input->frag_coord[VAR_Z] >= read_depth(y, x)){
return;
}
struct texture* tex = vars->uniform_texture[0];
vec2 tex_coord;
vec4 tex_color;
tex_coord[VAR_S] = input->attributes[0] / input->frag_coord[VAR_W];
tex_coord[VAR_T] = input->attributes[1] / input->frag_coord[VAR_W];
texture_lod(tex, tex_coord, 0.0f, tex_color);
write_color(y, x, tex_color[0], tex_color[1], tex_color[2], 1.0f);
write_depth(y, x, input->frag_coord[VAR_Z]);
}
/*
* Fragment shader for texture mapped cube. Calculation of perspective correct derivatives for trilinear filtering.
*/
static void fs_cube_grad(int y, int x, struct fragment_input *input, struct uniform_variables *vars){
if(input->frag_coord[VAR_Z] >= read_depth(y, x)){
return;
}
struct texture *tex = vars->uniform_texture[0];
vec2 tex_coord;
vec4 tex_color;
tex_coord[VAR_S] = input->attributes[0] / input->frag_coord[VAR_W];
tex_coord[VAR_T] = input->attributes[1] / input->frag_coord[VAR_W];
vec2 ddx, ddy;
float one_over_w2 = 1.0f / (input->frag_coord[VAR_W] * input->frag_coord[VAR_W]);
ddx[VAR_S] = (input->ddx[0] * input->frag_coord[VAR_W] - input->attributes[0] * input->dw_dx) * one_over_w2;
ddx[VAR_T] = (input->ddx[1] * input->frag_coord[VAR_W] - input->attributes[1] * input->dw_dx) * one_over_w2;
ddy[VAR_S] = (input->ddy[0] * input->frag_coord[VAR_W] - input->attributes[0] * input->dw_dy) * one_over_w2;
ddy[VAR_T] = (input->ddy[1] * input->frag_coord[VAR_W] - input->attributes[1] * input->dw_dy) * one_over_w2;
texture_grad(tex, tex_coord, ddx, ddy, tex_color);
write_color(y, x, tex_color[0], tex_color[1], tex_color[2], 1.0f);
write_depth(y, x, input->frag_coord[VAR_Z]);
}
static bool
check_slope_offset(const struct angle_axis *aa, GLdouble *ideal_mrd_near)
{
/* This function checks for correct slope-based offsets for a quad
* rotated to a given angle around a given axis.
*
* The basic strategy is to:
* Draw the quad. (Note: the quad's size and position
* are chosen so that it won't ever be clipped.)
* Sample three points in the quad's interior.
* Compute dz/dx and dz/dy based on those samples.
* Compute the range of allowable offsets; must be between
* max(abs(dz/dx), abs(dz/dy)) and
* sqrt((dz/dx)**2, (dz/dy)**2)
* Sample the depth of the quad at its center.
* Use PolygonOffset to produce an offset equal to one
* times the depth slope of the base quad.
* Draw another quad with the same orientation as the first.
* Sample the second quad at its center.
* Compute the difference in depths between the first quad
* and the second.
* Verify that the difference is within the allowable range.
* Repeat for a third quad at twice the offset from the first.
* (This verifies that the implementation is scaling
* the depth offset correctly.)
*/
const GLfloat quad_dist = 2.5; /* must be > 1+sqrt(2) to avoid */
/* clipping by the near plane */
GLdouble modelview_mat[16];
GLdouble projection_mat[16];
GLint viewport[4];
GLdouble centerw[3];
GLdouble base_depth;
GLdouble p0[3];
GLdouble p1[3];
GLdouble p2[3];
double det, dzdx, dzdy, mmax, mmin;
GLdouble offset_depth, offset;
glClearDepth(1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LESS);
glColor3f(1.0, 0.0, 0.0); /* red */
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0.0, 0.0, -quad_dist);
glRotatef(aa->angle, aa->axis[0], aa->axis[1], aa->axis[2]);
glGetDoublev(GL_MODELVIEW_MATRIX, modelview_mat);
glGetDoublev(GL_PROJECTION_MATRIX, projection_mat);
glGetIntegerv(GL_VIEWPORT, viewport);
glDisable(GL_POLYGON_OFFSET_FILL);
piglit_draw_rect(-1.0, -1.0, 2.0, 2.0);
project(0.0, 0.0, 0.0, modelview_mat, projection_mat, viewport,
centerw);
base_depth = read_depth(centerw[0], centerw[1]);
project(-0.9, -0.9, 0.0, modelview_mat, projection_mat, viewport, p0);
p0[2] = read_depth(p0[0], p0[1]);
project( 0.9, -0.9, 0.0, modelview_mat, projection_mat, viewport, p1);
p1[2] = read_depth(p1[0], p1[1]);
project( 0.9, 0.9, 0.0, modelview_mat, projection_mat, viewport, p2);
p2[2] = read_depth(p2[0], p2[1]);
det = (p0[0] - p1[0]) * (p0[1] - p2[1])
- (p0[0] - p2[0]) * (p0[1] - p1[1]);
if (fabs(det) < 0.001)
return false; /* too close to colinear to evaluate */
dzdx = ((p0[2] - p1[2]) * (p0[1] - p2[1])
- (p0[2] - p2[2]) * (p0[1] - p1[1])) / det;
dzdy = ((p0[0] - p1[0]) * (p0[2] - p2[2])
- (p0[0] - p2[0]) * (p0[2] - p1[2])) / det;
mmax = 1.1 * sqrt(dzdx * dzdx + dzdy * dzdy) + (*ideal_mrd_near);
/* (adding ideal_mrd_near is a fudge for roundoff error */
/* when the slope is extremely close to zero) */
mmin = 0.9 * fmax(fabs(dzdx), fabs(dzdy));
glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonOffset(-1.0, 0.0);
piglit_present_results();
piglit_draw_rect(-1.0, -1.0, 2.0, 2.0);
offset_depth = read_depth(centerw[0], centerw[1]);
offset = fmax(base_depth - offset_depth, 0.0);
if (offset < mmin || offset > mmax) {
if (offset < mmin)
printf("Depth-slope related offset was too small");
else
printf("Depth-slope related offset was too large");
printf("; first failure at:\n");
printf("\tAngle = %f degrees, axis = (%f, %f, %f)\n",
aa->angle, aa->axis[0], aa->axis[1], aa->axis[2]);
printf("\tFailing offset was %.16f\n", offset);
printf("\tAllowable range is (%f, %f)\n", mmin, mmax);
return false;
}
glPolygonOffset(-2.0, 0.0);
piglit_present_results();
piglit_draw_rect(-1.0, -1.0, 2.0, 2.0);
offset_depth = read_depth(centerw[0], centerw[1]);
offset = fmax(base_depth - offset_depth, 0.0);
if (offset < 2.0 * mmin || offset > 2.0 * mmax) {
if (offset < 2.0 * mmin)
printf("Depth-slope related offset was too small");
else
printf("Depth-slope related offset was too large");
printf("; first failure at:\n");
printf("\tAngle = %f degrees, axis = (%f, %f, %f)\n",
aa->angle, aa->axis[0], aa->axis[1], aa->axis[2]);
printf("\tFailing offset was %.16f\n", offset);
printf("\tAllowable range is (%f, %f)\n", 2.0 * mmin,
2.0 * mmax);
return false;
}
return true;
}