#include <GL/glew.h>
+#include <assert.h>
+#include <stddef.h>
+#include <algorithm>
#include <string>
#include "init.h"
#include "util.h"
+using namespace std;
+
bool movit_initialized = false;
MovitDebugLevel movit_debug_level = MOVIT_DEBUG_ON;
float movit_texel_subpixel_precision;
bool movit_srgb_textures_supported;
+int movit_num_wrongly_rounded;
+bool movit_shader_rounding_supported;
// The rules for objects with nontrivial constructors in static scope
// are somewhat convoluted, and easy to mess up. We simply have a
// pointer instead (and never care to clean it up).
-std::string *movit_data_directory = NULL;
+string *movit_data_directory = NULL;
namespace {
// Now generate a simple texture that's just [0,1].
GLuint src_texnum;
float texdata[] = { 0, 1 };
- glGenTextures(1, &dst_texnum);
+ glGenTextures(1, &src_texnum);
check_error();
- glBindTexture(GL_TEXTURE_1D, dst_texnum);
+ glBindTexture(GL_TEXTURE_1D, src_texnum);
check_error();
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
check_error();
float biggest_jump = 0.0f;
for (unsigned i = 1; i < width; ++i) {
assert(out_data[i] >= out_data[i - 1]);
- biggest_jump = std::max(biggest_jump, out_data[i] - out_data[i - 1]);
+ biggest_jump = max(biggest_jump, out_data[i] - out_data[i - 1]);
}
movit_texel_subpixel_precision = biggest_jump;
check_error();
}
+void measure_roundoff_problems()
+{
+ // Generate a destination texture to render to, and an FBO.
+ GLuint dst_texnum, fbo;
+
+ glGenTextures(1, &dst_texnum);
+ check_error();
+ glBindTexture(GL_TEXTURE_2D, dst_texnum);
+ check_error();
+ glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 512, 1, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
+ check_error();
+
+ glGenFramebuffers(1, &fbo);
+ check_error();
+ glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+ check_error();
+ glFramebufferTexture2D(
+ GL_FRAMEBUFFER,
+ GL_COLOR_ATTACHMENT0,
+ GL_TEXTURE_2D,
+ dst_texnum,
+ 0);
+ check_error();
+
+ // Now generate a texture where every value except the last should be
+ // rounded up to the next one. However, there are cards (in highly
+ // common use) that can't do this right, for unknown reasons.
+ GLuint src_texnum;
+ float texdata[512];
+ for (int i = 0; i < 256; ++i) {
+ texdata[i * 2 + 0] = (i + 0.48) / 255.0;
+ texdata[i * 2 + 1] = (i + 0.52) / 255.0;
+ }
+ glGenTextures(1, &src_texnum);
+ check_error();
+ glBindTexture(GL_TEXTURE_1D, src_texnum);
+ check_error();
+ glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+ check_error();
+ glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+ check_error();
+ glTexImage1D(GL_TEXTURE_1D, 0, GL_LUMINANCE32F_ARB, 512, 0, GL_LUMINANCE, GL_FLOAT, texdata);
+ check_error();
+ glEnable(GL_TEXTURE_1D);
+ check_error();
+
+ // Basic state.
+ glDisable(GL_BLEND);
+ check_error();
+ glDisable(GL_DEPTH_TEST);
+ check_error();
+ glDepthMask(GL_FALSE);
+ check_error();
+
+ glViewport(0, 0, 512, 1);
+
+ glMatrixMode(GL_PROJECTION);
+ glLoadIdentity();
+ glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, 1.0);
+
+ glMatrixMode(GL_MODELVIEW);
+ glLoadIdentity();
+ check_error();
+
+ // Draw the texture stretched over a long quad, interpolating it out.
+ glBegin(GL_QUADS);
+
+ glTexCoord1f(0.0f);
+ glVertex2f(0.0f, 0.0f);
+
+ glTexCoord1f(1.0f);
+ glVertex2f(1.0f, 0.0f);
+
+ glTexCoord1f(1.0f);
+ glVertex2f(1.0f, 1.0f);
+
+ glTexCoord1f(0.0f);
+ glVertex2f(0.0f, 1.0f);
+
+ glEnd();
+ check_error();
+
+ glDisable(GL_TEXTURE_1D);
+ check_error();
+
+ // Now read the data back and see what the card did. (Ignore the last value.)
+ // (We only look at the red channel; the others will surely be the same.)
+ unsigned char out_data[512];
+ glReadPixels(0, 0, 512, 1, GL_RED, GL_UNSIGNED_BYTE, out_data);
+ check_error();
+
+ int wrongly_rounded = 0;
+ for (unsigned i = 0; i < 255; ++i) {
+ if (out_data[i * 2 + 0] != i) {
+ ++wrongly_rounded;
+ }
+ if (out_data[i * 2 + 1] != i + 1) {
+ ++wrongly_rounded;
+ }
+ }
+
+ movit_num_wrongly_rounded = wrongly_rounded;
+
+ // Clean up.
+ glBindTexture(GL_TEXTURE_1D, 0);
+ check_error();
+ glBindFramebuffer(GL_FRAMEBUFFER, 0);
+ check_error();
+ glDeleteFramebuffers(1, &fbo);
+ check_error();
+ glDeleteTextures(1, &dst_texnum);
+ check_error();
+ glDeleteTextures(1, &src_texnum);
+ check_error();
+}
+
void check_extensions()
{
// We fundamentally need FBOs and floating-point textures.
// sRGB texture decode would be nice, but are not mandatory
// (GammaExpansionEffect can do the same thing if needed).
movit_srgb_textures_supported = glewIsSupported("GL_EXT_texture_sRGB");
+
+ // We may want to use round() at the end of the final shader,
+ // if supported. We need either GLSL 1.30 or this extension to do that,
+ // and 1.30 brings with it other things that we don't want to demand
+ // for now.
+ movit_shader_rounding_supported = glewIsSupported("GL_EXT_gpu_shader4");
}
} // namespace
-void init_movit(const std::string& data_directory, MovitDebugLevel debug_level)
+void init_movit(const string& data_directory, MovitDebugLevel debug_level)
{
if (movit_initialized) {
return;
}
- movit_data_directory = new std::string(data_directory);
+ movit_data_directory = new string(data_directory);
movit_debug_level = debug_level;
glewInit();
// geez
glPixelStorei(GL_PACK_ALIGNMENT, 1);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+ glDisable(GL_DITHER);
measure_texel_subpixel_precision();
+ measure_roundoff_problems();
check_extensions();
movit_initialized = true;
projects / movit / blobdiff