// Dies if the file does not exist.
std::string read_file(const std::string &filename);
+// Reads <base>.<extension>, <base>.130.<extension> or <base>.300es.<extension> and
+// returns its contents, depending on <movit_shader_level>.
+std::string read_version_dependent_file(const std::string &base, const std::string &extension);
+
// Compile the given GLSL shader (typically a vertex or fragment shader)
// and return the object number.
GLuint compile_shader(const std::string &shader_src, GLenum type);
// Calculate a / b, rounding up. Does not handle overflow correctly.
unsigned div_round_up(unsigned a, unsigned b);
+enum CombineRoundingBehavior {
+ COMBINE_DO_NOT_ROUND = 0,
+ COMBINE_ROUND_TO_FP16 = 1,
+};
+
// Calculate where to sample, and with what weight, if one wants to use
-// the GPU's bilinear hardware to sample w1 * x[0] + w2 * x[1].
+// 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>.
//
// Note that since the GPU might have limited precision in its linear
// interpolation, the effective weights might be different from the ones you
// asked for. sum_sq_error, if not NULL, will contain the sum of the
// (estimated) squared errors of the two weights.
-void combine_two_samples(float w1, float w2, float *offset, float *total_weight, float *sum_sq_error);
+//
+// The answer, in "offset", comes as a normalized coordinate,
+// so if e.g. w2 = 0, you have simply offset = pos1. If <rounding_behavior>
+// is COMBINE_ROUND_TO_FP16, the coordinate is assumed to be stored as a
+// 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);
// Create a VBO with the given data, and bind it to the vertex attribute
// with name <attribute_name>. Returns the VBO number.
// Clean up after fill_vertex_attribute().
void cleanup_vertex_attribute(GLuint glsl_program_num, const std::string &attribute_name, GLuint vbo);
+// If v is not already a power of two, return the first higher power of two.
+unsigned next_power_of_two(unsigned v);
+
+// Get a pointer that represents the current OpenGL context, in a cross-platform way.
+// This is not intended for anything but identification (ie., so you can associate
+// different FBOs with different contexts); you should probably not try to cast it
+// back into anything you intend to pass into OpenGL.
+void *get_gl_context_identifier();
+
} // namespace movit
#ifdef NDEBUG