+#define GL_GLEXT_PROTOTYPES 1
+
+#include <string.h>
+#include <GL/gl.h>
+#include <GL/glext.h>
+#include <assert.h>
+
+#include "input.h"
+#include "util.h"
+
+Input::Input(ImageFormat image_format, unsigned width, unsigned height)
+ : image_format(image_format),
+ needs_update(false),
+ use_srgb_texture_format(false),
+ needs_mipmaps(false),
+ width(width),
+ height(height)
+{
+ register_int("use_srgb_texture_format", &use_srgb_texture_format);
+ register_int("needs_mipmaps", &needs_mipmaps);
+}
+
+void Input::finalize()
+{
+ // Translate the input format to OpenGL's enums.
+ GLenum internal_format;
+ if (use_srgb_texture_format) {
+ internal_format = GL_SRGB8;
+ } else {
+ internal_format = GL_RGBA8;
+ }
+ if (image_format.pixel_format == FORMAT_RGB) {
+ format = GL_RGB;
+ bytes_per_pixel = 3;
+ } else if (image_format.pixel_format == FORMAT_RGBA) {
+ format = GL_RGBA;
+ bytes_per_pixel = 4;
+ } else if (image_format.pixel_format == FORMAT_BGR) {
+ format = GL_BGR;
+ bytes_per_pixel = 3;
+ } else if (image_format.pixel_format == FORMAT_BGRA) {
+ format = GL_BGRA;
+ bytes_per_pixel = 4;
+ } else {
+ assert(false);
+ }
+
+ // Create PBO to hold the texture holding the input image, and then the texture itself.
+ glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 2);
+ check_error();
+ glBufferData(GL_PIXEL_UNPACK_BUFFER_ARB, width * height * bytes_per_pixel, NULL, GL_STREAM_DRAW);
+ check_error();
+ glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
+ check_error();
+
+ glGenTextures(1, &texture_num);
+ check_error();
+ glBindTexture(GL_TEXTURE_2D, texture_num);
+ check_error();
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+ check_error();
+ // Intel/Mesa seems to have a broken glGenerateMipmap() for non-FBO textures, so do it here
+ // instead of calling glGenerateMipmap().
+ glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, needs_mipmaps);
+ check_error();
+ glTexImage2D(GL_TEXTURE_2D, 0, internal_format, width, height, 0, format, GL_UNSIGNED_BYTE, NULL);
+ check_error();
+
+ needs_update = false;
+}
+
+void Input::set_gl_state(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num)
+{
+ if (needs_update) {
+ // Copy the pixel data into the PBO.
+ glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 2);
+ check_error();
+ void *mapped_pbo = glMapBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB, GL_WRITE_ONLY);
+ memcpy(mapped_pbo, pixel_data, width * height * bytes_per_pixel);
+ glUnmapBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB);
+ check_error();
+
+ // Re-upload the texture from the PBO.
+ glActiveTexture(GL_TEXTURE0);
+ check_error();
+ glBindTexture(GL_TEXTURE_2D, texture_num);
+ check_error();
+ glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, format, GL_UNSIGNED_BYTE, BUFFER_OFFSET(0));
+ check_error();
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+ check_error();
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+ check_error();
+ glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
+ check_error();
+
+ needs_update = false;
+ }
+
+ // Bind it to a sampler.
+ set_uniform_int(glsl_program_num, prefix, "tex", *sampler_num);
+ ++*sampler_num;
+}
+
+std::string Input::output_fragment_shader()
+{
+ return read_file("input.frag");
+}