--- /dev/null
+#include <math.h>
+#include <GL/glew.h>
+
+#include "padding_effect.h"
+#include "util.h"
+
+PaddingEffect::PaddingEffect()
+ : border_color(0.0f, 0.0f, 0.0f, 0.0f),
+ output_width(1280),
+ output_height(720),
+ top(0),
+ left(0)
+{
+ register_vec4("border_color", (float *)&border_color);
+ register_int("width", &output_width);
+ register_int("height", &output_height);
+ register_float("top", &top);
+ register_float("left", &left);
+}
+
+std::string PaddingEffect::output_fragment_shader()
+{
+ return read_file("padding_effect.frag");
+}
+
+void PaddingEffect::set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num)
+{
+ Effect::set_gl_state(glsl_program_num, prefix, sampler_num);
+
+ float offset[2] = {
+ left / output_width,
+ (output_height - input_height - top) / output_height
+ };
+ set_uniform_vec2(glsl_program_num, prefix, "offset", offset);
+
+ float scale[2] = {
+ float(output_width) / input_width,
+ float(output_height) / input_height
+ };
+ set_uniform_vec2(glsl_program_num, prefix, "scale", scale);
+
+ // Due to roundoff errors, the test against 0.5 is seldom exact,
+ // even though we test for less than and not less-than-or-equal.
+ // We'd rather keep an extra border pixel in those very rare cases
+ // (where the image is shifted pretty much exactly a half-pixel)
+ // than losing a pixel in the common cases of integer shift.
+ // Thus the 1e-3 fudge factors.
+ float texcoord_min[2] = {
+ (0.5f - 1e-3) / input_width,
+ (0.5f - 1e-3) / input_height
+ };
+ set_uniform_vec2(glsl_program_num, prefix, "texcoord_min", texcoord_min);
+
+ float texcoord_max[2] = {
+ 1.0f - (0.5f - 1e-3) / input_width,
+ 1.0f - (0.5f - 1e-3) / input_height
+ };
+ set_uniform_vec2(glsl_program_num, prefix, "texcoord_max", texcoord_max);
+}
+
+// We don't change the pixels of the image itself, so the only thing that
+// can make us less flexible is if the border color can be interpreted
+// differently in different modes.
+
+// 0.0 and 1.0 are interpreted the same, no matter the gamma ramp.
+// Alpha is not affected by gamma.
+bool PaddingEffect::needs_linear_light() const
+{
+ if ((border_color.r == 0.0 || border_color.r == 1.0) &&
+ (border_color.g == 0.0 || border_color.g == 1.0) &&
+ (border_color.b == 0.0 || border_color.b == 1.0)) {
+ return false;
+ }
+ return true;
+}
+
+// The white point is the same (D65) in all the color spaces we currently support,
+// so any gray would be okay, but we don't really have a guarantee for that.
+// Stay safe and say that only pure black and pure white is okay.
+// Alpha is not affected by color space.
+bool PaddingEffect::needs_srgb_primaries() const
+{
+ if (border_color.r == 0.0 && border_color.g == 0.0 && border_color.b == 0.0) {
+ return false;
+ }
+ if (border_color.r == 1.0 && border_color.g == 1.0 && border_color.b == 1.0) {
+ return false;
+ }
+ return true;
+}
+
+// If the border color is black, it doesn't matter if we're pre- or postmultiplied
+// (or even blank, as a hack). Otherwise, it does.
+Effect::AlphaHandling PaddingEffect::alpha_handling() const
+{
+ if (border_color.r == 0.0 && border_color.g == 0.0 && border_color.b == 0.0) {
+ return DONT_CARE_ALPHA_TYPE;
+ }
+ return INPUT_AND_OUTPUT_ALPHA_PREMULTIPLIED;
+}
+
+void PaddingEffect::get_output_size(unsigned *width, unsigned *height) const
+{
+ *width = output_width;
+ *height = output_height;
+}
+
+void PaddingEffect::inform_input_size(unsigned input_num, unsigned width, unsigned height)
+{
+ assert(input_num == 0);
+ input_width = width;
+ input_height = height;
+}
--- /dev/null
+uniform vec2 PREFIX(offset);
+uniform vec2 PREFIX(scale);
+uniform vec2 PREFIX(texcoord_min);
+uniform vec2 PREFIX(texcoord_max);
+
+vec4 FUNCNAME(vec2 tc) {
+ tc -= PREFIX(offset);
+ tc *= PREFIX(scale);
+
+#if 1
+ if (any(lessThan(tc, PREFIX(texcoord_min))) ||
+ any(greaterThan(tc, PREFIX(texcoord_max)))) {
+ return PREFIX(border_color);
+ }
+#endif
+ if (any(lessThan(tc, vec2(0.0))) ||
+ any(greaterThan(tc, vec2(1.0)))) {
+ return PREFIX(border_color);
+ }
+#if 0
+ // In theory, maybe we should test on the outmost textel centers
+ // (e.g. (0.5/width, 0.5/height) for the top-left) instead of the
+ // texture border. However, since we only support integer padding
+ if (any(lessThan(tc, vec2(0.0))) || any(greaterThan(tc, vec2(1.0)))) {
+ return PREFIX(border_color);
+ }
+#endif
+
+ return INPUT(tc);
+}
--- /dev/null
+#ifndef _PADDING_EFFECT_H
+#define _PADDING_EFFECT_H 1
+
+// Takes an image and pads it to fit a larger image, or crops it to fit a smaller one
+// (although the latter is implemented slightly less efficiently, and you cannot both
+// pad and crop in the same effect).
+//
+// The source image is cut off at the texel borders (so there is no interpolation
+// outside them), and then given a user-specific color; by default, full transparent.
+//
+// The border color is taken to be in linear gamma, sRGB, with premultiplied alpha.
+// You may not change it after calling finalize(), since that could change the
+// graph (need_linear_light() etc. depend on the border color you choose).
+
+#include "effect.h"
+
+class PaddingEffect : public Effect {
+public:
+ PaddingEffect();
+ virtual std::string effect_type_id() const { return "PaddingEffect"; }
+ std::string output_fragment_shader();
+ void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num);
+
+ virtual bool needs_linear_light() const;
+ virtual bool needs_srgb_primaries() const;
+ virtual AlphaHandling alpha_handling() const;
+
+ virtual bool changes_output_size() const { return true; }
+ virtual void get_output_size(unsigned *width, unsigned *height) const;
+ virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height);
+
+private:
+ RGBATriplet border_color;
+ int input_width, input_height;
+ int output_width, output_height;
+ float top, left;
+};
+
+#endif // !defined(_PADDING_EFFECT_H)