Add support for multiple shader models.

[movit] / init.cpp

diff --git a/init.cpp b/init.cpp
index 671c507c5588c7faf5783b7f0a500d1780fc9162..4802c68712e3b69b086eb5877da28528fc457c3f 100644 (file)
--- a/init.cpp
+++ b/init.cpp
@@ -18,6 +18,7 @@ float movit_texel_subpixel_precision;
 bool movit_srgb_textures_supported;
 int movit_num_wrongly_rounded;
 bool movit_shader_rounding_supported;
+MovitShaderModel movit_shader_model;
 
 // The rules for objects with nontrivial constructors in static scope
 // are somewhat convoluted, and easy to mess up. We simply have a
@@ -38,7 +39,7 @@ void measure_texel_subpixel_precision()
        check_error();
        glBindTexture(GL_TEXTURE_2D, dst_texnum);
        check_error();
-       glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F_ARB, width, 1, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
+       glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, width, 1, 0, GL_RGBA, GL_FLOAT, NULL);
        check_error();
 
        glGenFramebuffers(1, &fbo);
@@ -78,7 +79,8 @@ void measure_texel_subpixel_precision()
        glViewport(0, 0, width, 1);
 
        GLuint glsl_program_num = resource_pool.compile_glsl_program(
-               read_file("vs.vert"), read_file("texture1d.frag"));
+               read_version_dependent_file("vs", "vert"),
+               read_version_dependent_file("texture1d", "frag"));
        glUseProgram(glsl_program_num);
        check_error();
        glUniform1i(glGetUniformLocation(glsl_program_num, "tex"), 0);  // Bind the 2D sampler.
@@ -122,14 +124,14 @@ void measure_texel_subpixel_precision()
        // Now read the data back and see what the card did.
        // (We only look at the red channel; the others will surely be the same.)
        // We assume a linear ramp; anything else will give sort of odd results here.
-       float out_data[width];
-       glReadPixels(0, 0, width, 1, GL_RED, GL_FLOAT, out_data);
+       float out_data[width * 4];
+       glReadPixels(0, 0, width, 1, GL_RGBA, GL_FLOAT, out_data);
        check_error();
 
        float biggest_jump = 0.0f;
        for (unsigned i = 1; i < width; ++i) {
-               assert(out_data[i] >= out_data[i - 1]);
-               biggest_jump = max(biggest_jump, out_data[i] - out_data[i - 1]);
+               assert(out_data[i * 4] >= out_data[(i - 1) * 4]);
+               biggest_jump = max(biggest_jump, out_data[i * 4] - out_data[(i - 1) * 4]);
        }
 
        assert(biggest_jump > 0.0);
@@ -209,7 +211,8 @@ void measure_roundoff_problems()
        glViewport(0, 0, 512, 1);
 
        GLuint glsl_program_num = resource_pool.compile_glsl_program(
-               read_file("vs.vert"), read_file("texture1d.frag"));
+               read_version_dependent_file("vs", "vert"),
+               read_version_dependent_file("texture1d", "frag"));
        glUseProgram(glsl_program_num);
        check_error();
        glUniform1i(glGetUniformLocation(glsl_program_num, "tex"), 0);  // Bind the 2D sampler.
@@ -242,16 +245,16 @@ void measure_roundoff_problems()
 
        // 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);
+       unsigned char out_data[512 * 4];
+       glReadPixels(0, 0, 512, 1, GL_RGBA, 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) {
+               if (out_data[(i * 2 + 0) * 4] != i) {
                        ++wrongly_rounded;
                }
-               if (out_data[i * 2 + 1] != i + 1) {
+               if (out_data[(i * 2 + 1) * 4] != i + 1) {
                        ++wrongly_rounded;
                }
        }
@@ -277,6 +280,21 @@ void measure_roundoff_problems()
 
 bool check_extensions()
 {
+       // GLES generally doesn't use extensions as actively as desktop OpenGL.
+       // For now, we say that for GLES, we require GLES 3, which has everything
+       // we need.
+       //
+       // Since we use implicit #version 100, we don't have round(). We will
+       // fix this at some later stage.
+       if (!epoxy_is_desktop_gl()) {
+               if (epoxy_gl_version() >= 30) {
+                       movit_srgb_textures_supported = true;
+                       movit_shader_rounding_supported = false;
+               } else {
+                       return false;
+               }
+       }
+
        // We fundamentally need FBOs and floating-point textures.
        // FBOs are covered by OpenGL 1.5, and are not an extension there.
        // Floating-point textures are part of OpenGL 3.0 and newer.
@@ -319,6 +337,31 @@ bool check_extensions()
        return true;
 }
 
+double get_glsl_version()
+{
+       char *glsl_version_str = strdup((const char *)glGetString(GL_SHADING_LANGUAGE_VERSION));
+
+       // Skip past the first period.
+       char *ptr = strchr(glsl_version_str, '.');
+       assert(ptr != NULL);
+       ++ptr;
+
+       // Now cut the string off at the next period or space, whatever comes first
+       // (unless the string ends first).
+       while (*ptr && *ptr != '.' && *ptr != ' ') {
+               ++ptr;
+       }
+       *ptr = '\0';
+
+       // Now we have something on the form X.YY. We convert it to a float, and hope
+       // that if it's inexact (e.g. 1.30), atof() will round the same way the
+       // compiler will.
+       float glsl_version = atof(glsl_version_str);
+       free(glsl_version_str);
+
+       return glsl_version;
+}
+
 }  // namespace
 
 bool init_movit(const string& data_directory, MovitDebugLevel debug_level)
@@ -338,6 +381,18 @@ bool init_movit(const string& data_directory, MovitDebugLevel debug_level)
        if (!check_extensions()) {
                return false;
        }
+
+       // Find out what shader model we should compile for.
+       if (epoxy_is_desktop_gl()) {
+               if (get_glsl_version() >= 1.30) {
+                       movit_shader_model = MOVIT_GLSL_130;
+               } else {
+                       movit_shader_model = MOVIT_GLSL_110;
+               }
+       } else {
+               movit_shader_model = MOVIT_ESSL_300;
+       }
+
        measure_texel_subpixel_precision();
        measure_roundoff_problems();