#include <stdlib.h>
#include <Eigen/Core>
#include <string>
+#include "defs.h"
+#include "fp16.h"
#define BUFFER_OFFSET(i) ((char *)NULL + (i))
// Output a GLSL 3x3 matrix declaration.
std::string output_glsl_mat3(const std::string &name, const Eigen::Matrix3d &m);
+// Output GLSL scalar, 2-length and 3-length vector declarations.
+std::string output_glsl_float(const std::string &name, float x);
+std::string output_glsl_vec2(const std::string &name, float x, float y);
+std::string output_glsl_vec3(const std::string &name, float x, float y, float z);
+
// Calculate a / b, rounding up. Does not handle overflow correctly.
unsigned div_round_up(unsigned a, unsigned b);
// Calculate where to sample, and with what weight, if one wants to use
// the GPU's bilinear hardware to sample w1 * x[pos1] + w2 * x[pos2],
// where pos1 and pos2 must be normalized coordinates describing neighboring
-// pixels in the mipmap level at which you sample, and the total number of
-// pixels (in given mipmap level) is <size>.
+// texels in the mipmap level at which you sample. <num_subtexels> is the
+// number of distinct accessible subtexels in the given mipmap level,
+// calculated by num_texels / movit_texel_subpixel_precision. It is a float
+// for performance reasons, even though it is expected to be a whole number.
+// <inv_num_subtexels> is simply its inverse (1/x). <pos1_pos2_diff> is
+// (pos2-pos1) and <inv_pos1_pos2_diff> is 1/(pos2-pos1).
//
// Note that since the GPU might have limited precision in its linear
// interpolation, the effective weights might be different from the ones you
// rounded fp16 value. This enables more precise calculation of total_weight
// and sum_sq_error.
template<class DestFloat>
-void combine_two_samples(float w1, float w2, float pos1, float pos2, unsigned size,
- DestFloat *offset, DestFloat *total_weight, float *sum_sq_error);
+void combine_two_samples(float w1, float w2, float pos1, float pos1_pos2_diff, float inv_pos1_pos2_diff, float num_subtexels, float inv_num_subtexels,
+ DestFloat *offset, DestFloat *total_weight, float *sum_sq_error)
+{
+ assert(w1 * w2 >= 0.0f); // Should not have differing signs.
+ float z; // Normalized 0..1 between pos1 and pos2.
+ if (fabs(w1 + w2) < 1e-6) {
+ z = 0.5f;
+ } else {
+ z = w2 / (w1 + w2);
+ }
+
+ // Round to the desired precision. Note that this might take z outside the 0..1 range.
+ *offset = from_fp32<DestFloat>(pos1 + z * pos1_pos2_diff);
+ z = (to_fp32(*offset) - pos1) * inv_pos1_pos2_diff;
+
+ // Round to the minimum number of bits we have measured earlier.
+ // The card will do this for us anyway, but if we know what the real z
+ // is, we can pick a better total_weight below.
+ z = lrintf(z * num_subtexels) * inv_num_subtexels;
+
+ // Choose total weight w so that we minimize total squared error
+ // for the effective weights:
+ //
+ // e = (w(1-z) - a)² + (wz - b)²
+ //
+ // Differentiating by w and setting equal to zero:
+ //
+ // 2(w(1-z) - a)(1-z) + 2(wz - b)z = 0
+ // w(1-z)² - a(1-z) + wz² - bz = 0
+ // w((1-z)² + z²) = a(1-z) + bz
+ // w = (a(1-z) + bz) / ((1-z)² + z²)
+ //
+ // If z had infinite precision, this would simply reduce to w = w1 + w2.
+ *total_weight = from_fp32<DestFloat>((w1 + z * (w2 - w1)) / (z * z + (1 - z) * (1 - z)));
+
+ if (sum_sq_error != NULL) {
+ float err1 = to_fp32(*total_weight) * (1 - z) - w1;
+ float err2 = to_fp32(*total_weight) * z - w2;
+ *sum_sq_error = err1 * err1 + err2 * err2;
+ }
+}
+
+// Create a VBO with the given data. Returns the VBO number.
+GLuint generate_vbo(GLint size, GLenum type, GLsizeiptr data_size, const GLvoid *data);
// Create a VBO with the given data, and bind it to the vertex attribute
// with name <attribute_name>. Returns the VBO number.
// back into anything you intend to pass into OpenGL.
void *get_gl_context_identifier();
+// Used in the check_error() macro, below.
+void abort_gl_error(GLenum err, const char *filename, int line) DOES_NOT_RETURN;
+
} // namespace movit
#ifdef NDEBUG
#define check_error()
#else
-#define check_error() { int err = glGetError(); if (err != GL_NO_ERROR) { printf("GL error 0x%x at %s:%d\n", err, __FILE__, __LINE__); abort(); } }
+#define check_error() { GLenum err = glGetError(); if (err != GL_NO_ERROR) { movit::abort_gl_error(err, __FILE__, __LINE__); } }
#endif
// CHECK() is like assert(), but retains any side effects no matter the compilation mode.
projects / movit / blobdiff