constexpr unsigned patch_size_pixels = 12;
// Some global OpenGL objects.
-GLuint nearest_sampler, linear_sampler;
+GLuint nearest_sampler, linear_sampler, smoothness_sampler;
GLuint vertex_vbo;
string read_file(const string &filename)
// Set up the equations set (two equations in two unknowns, per pixel).
// We store five floats; the three non-redundant elements of the 2x2 matrix (A)
// as 32-bit floats, and the two elements on the right-hand side (b) as 16-bit
-// floats. This fits into four u32 values; R, G, B for the matrix (the last
-// element is symmetric) and A for the two b values. All the values of the
-// energy term (E_I, E_G, E_S), except the smoothness terms that depend on
-// other pixels, are calculated in one pass.
+// floats. (Actually, we store the inverse of the diagonal elements, because
+// we only ever need to divide by them.) This fits into four u32 values;
+// R, G, B for the matrix (the last element is symmetric) and A for the two b values.
+// All the values of the energy term (E_I, E_G, E_S), except the smoothness
+// terms that depend on other pixels, are calculated in one pass.
//
// See variational_refinement.txt for more information.
class SetupEquations {
void exec(GLuint I_x_y_tex, GLuint I_t_tex, GLuint diff_flow_tex, GLuint flow_tex, GLuint beta_0_tex, GLuint smoothness_x_tex, GLuint smoothness_y_tex, GLuint equation_tex, int level_width, int level_height);
private:
- GLuint smoothness_sampler;
-
GLuint equations_vs_obj;
GLuint equations_fs_obj;
GLuint equations_program;
SetupEquations::SetupEquations()
{
- // The smoothness is sampled so that once we get to a smoothness involving
- // a value outside the border, the diffusivity between the two becomes zero.
- glCreateSamplers(1, &smoothness_sampler);
- glSamplerParameteri(smoothness_sampler, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
- glSamplerParameteri(smoothness_sampler, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
- glSamplerParameteri(smoothness_sampler, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
- glSamplerParameteri(smoothness_sampler, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
- float zero[] = { 0.0f, 0.0f, 0.0f, 0.0f };
- glSamplerParameterfv(smoothness_sampler, GL_TEXTURE_BORDER_COLOR, zero);
-
equations_vs_obj = compile_shader(read_file("vs.vert"), GL_VERTEX_SHADER);
equations_fs_obj = compile_shader(read_file("equations.frag"), GL_FRAGMENT_SHADER);
equations_program = link_program(equations_vs_obj, equations_fs_obj);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
}
+// Calculate the smoothness constraints between neighboring pixels;
+// s_x(x,y) stores smoothness between pixel (x,y) and (x+1,y),
+// and s_y(x,y) stores between (x,y) and (x,y+1). We'll sample with
+// border color (0,0) later, so that there's zero diffusion out of
+// the border.
+//
+// See variational_refinement.txt for more information.
+class SOR {
+public:
+ SOR();
+ void exec(GLuint diff_flow_tex, GLuint equation_tex, GLuint smoothness_x_tex, GLuint smoothness_y_tex, int level_width, int level_height, int num_iterations);
+
+private:
+ GLuint sor_vs_obj;
+ GLuint sor_fs_obj;
+ GLuint sor_program;
+ GLuint sor_vao;
+
+ GLuint uniform_diff_flow_tex;
+ GLuint uniform_equation_tex;
+ GLuint uniform_smoothness_x_tex, uniform_smoothness_y_tex;
+};
+
+SOR::SOR()
+{
+ sor_vs_obj = compile_shader(read_file("vs.vert"), GL_VERTEX_SHADER);
+ sor_fs_obj = compile_shader(read_file("sor.frag"), GL_FRAGMENT_SHADER);
+ sor_program = link_program(sor_vs_obj, sor_fs_obj);
+
+ // Set up the VAO containing all the required position/texcoord data.
+ glCreateVertexArrays(1, &sor_vao);
+ glBindVertexArray(sor_vao);
+ glBindBuffer(GL_ARRAY_BUFFER, vertex_vbo);
+
+ GLint position_attrib = glGetAttribLocation(sor_program, "position");
+ glEnableVertexArrayAttrib(sor_vao, position_attrib);
+ glVertexAttribPointer(position_attrib, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));
+
+ uniform_diff_flow_tex = glGetUniformLocation(sor_program, "diff_flow_tex");
+ uniform_equation_tex = glGetUniformLocation(sor_program, "equation_tex");
+}
+
+void SOR::exec(GLuint diff_flow_tex, GLuint equation_tex, GLuint smoothness_x_tex, GLuint smoothness_y_tex, int level_width, int level_height, int num_iterations)
+{
+ glUseProgram(sor_program);
+
+ bind_sampler(sor_program, uniform_diff_flow_tex, 0, diff_flow_tex, nearest_sampler);
+ bind_sampler(sor_program, uniform_smoothness_x_tex, 1, smoothness_x_tex, smoothness_sampler);
+ bind_sampler(sor_program, uniform_smoothness_y_tex, 2, smoothness_y_tex, smoothness_sampler);
+ bind_sampler(sor_program, uniform_equation_tex, 3, equation_tex, nearest_sampler);
+
+ GLuint sor_fbo; // TODO: cleanup
+ glCreateFramebuffers(1, &sor_fbo);
+ glNamedFramebufferTexture(sor_fbo, GL_COLOR_ATTACHMENT0, diff_flow_tex, 0); // NOTE: Bind to same as we render from!
+
+ glViewport(0, 0, level_width, level_height);
+ glDisable(GL_BLEND);
+ glBindVertexArray(sor_vao);
+ glBindFramebuffer(GL_FRAMEBUFFER, sor_fbo);
+
+ for (int i = 0; i < num_iterations; ++i) {
+ glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+ if (i != num_iterations - 1) {
+ glTextureBarrier();
+ }
+ }
+}
+
int main(void)
{
if (SDL_Init(SDL_INIT_EVERYTHING) == -1) {
glSamplerParameteri(linear_sampler, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glSamplerParameteri(linear_sampler, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+ // The smoothness is sampled so that once we get to a smoothness involving
+ // a value outside the border, the diffusivity between the two becomes zero.
+ glCreateSamplers(1, &smoothness_sampler);
+ glSamplerParameteri(smoothness_sampler, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+ glSamplerParameteri(smoothness_sampler, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+ glSamplerParameteri(smoothness_sampler, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
+ glSamplerParameteri(smoothness_sampler, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
+ float zero[] = { 0.0f, 0.0f, 0.0f, 0.0f };
+ glSamplerParameterfv(smoothness_sampler, GL_TEXTURE_BORDER_COLOR, zero);
+
float vertices[] = {
0.0f, 1.0f,
0.0f, 0.0f,
Derivatives derivatives;
ComputeSmoothness compute_smoothness;
SetupEquations setup_equations;
+ SOR sor;
GLuint query;
glGenQueries(1, &query);
// Set up the 2x2 equation system for each pixel.
setup_equations.exec(I_x_y_tex, I_t_tex, du_dv_tex, dense_flow_tex, beta_0_tex, smoothness_x_tex, smoothness_y_tex, equation_tex, level_width, level_height);
+
+ // Run a few SOR (or quasi-SOR, since we're not really Jacobi) iterations.
+ // Note that these are to/from the same texture.
+ sor.exec(du_dv_tex, equation_tex, smoothness_x_tex, smoothness_y_tex, level_width, level_height, 5);
}
prev_level_flow_tex = dense_flow_tex;
--- /dev/null
+#version 450 core
+
+in vec2 tc;
+out vec2 diff_flow;
+
+uniform sampler2D diff_flow_tex, smoothness_x_tex, smoothness_y_tex;
+uniform usampler2D equation_tex;
+
+void main()
+{
+ uvec4 equation = texture(equation_tex, tc);
+ float inv_A11 = uintBitsToFloat(equation.x);
+ float A12 = uintBitsToFloat(equation.y);
+ float inv_A22 = uintBitsToFloat(equation.z);
+ vec2 b = unpackHalf2x16(equation.w);
+
+ // Subtract the missing terms from the right-hand side
+ // (it couldn't be done earlier, because we didn't know
+ // the values of the neighboring pixels; they change for
+ // each SOR iteration).
+ // TODO: Multiply by some gamma.
+ float smooth_l = textureOffset(smoothness_x_tex, tc, ivec2(-1, 0)).x;
+ float smooth_r = texture(smoothness_x_tex, tc).x;
+ float smooth_d = textureOffset(smoothness_y_tex, tc, ivec2( 0, -1)).x;
+ float smooth_u = texture(smoothness_y_tex, tc).x;
+ b -= smooth_l * textureOffset(diff_flow_tex, tc, ivec2(-1, 0)).xy;
+ b -= smooth_r * textureOffset(diff_flow_tex, tc, ivec2( 1, 0)).xy;
+ b -= smooth_d * textureOffset(diff_flow_tex, tc, ivec2( 0, -1)).xy;
+ b -= smooth_u * textureOffset(diff_flow_tex, tc, ivec2( 0, 1)).xy;
+
+ const float omega = 1.6;
+ diff_flow = texture(diff_flow_tex, tc).xy;
+
+ // From https://en.wikipedia.org/wiki/Successive_over-relaxation.
+ float sigma_u = A12 * diff_flow.y;
+ diff_flow.x += omega * ((b.x - sigma_u) * inv_A11 - diff_flow.x);
+ float sigma_v = A12 * diff_flow.x;
+ diff_flow.y += omega * ((b.y - sigma_v) * inv_A22 - diff_flow.y);
+}
projects / nageru / commitdiff