[Feat] (SelfTest/DriverPost): add a noperspective correctness check to the GLES POST - render a strong-perspective quad and read the centre texel to verify the varying interpolates screen-linear (not perspective-correct), carried through the native GL_NV_shader_noperspective_interpolation path when present or MobileGL's exact gl_Position.w/gl_FragCoord.w emulation when absent. PASS = native and correct; WARN = emulated and correct (the fallback path shipping packs hit on such devices); FAIL = interpolation wrong/perspective-correct, or the program will not build. The ESSL header matches the device version because noperspective is rejected at #version 300 es on some drivers even with the extension enabled

This commit is contained in:
2026-07-21 02:09:17 -04:00
parent 79feeffd25
commit 52ddb440ca
+225
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@@ -401,6 +401,230 @@ namespace MobileGL::MG_Util::SelfTest {
disabledNote);
}
// Compiles + links a two-stage program on the probe context. Returns 0 on failure and writes a
// human-readable reason into |detail|.
GLuint CompileLinkProgram(const MG_External::GLESFunctionsTable& g, const char* vs, const char* fs,
String& detail) {
const auto compile = [&](GLenum stage, const char* src, GLuint& out) -> bool {
out = g.glCreateShader(stage);
if (out == 0) {
detail = "glCreateShader returned 0";
return false;
}
g.glShaderSource(out, 1, &src, nullptr);
g.glCompileShader(out);
GLint ok = GL_FALSE;
g.glGetShaderiv(out, GL_COMPILE_STATUS, &ok);
if (ok != GL_TRUE) {
GLchar log[512] = {};
GLsizei len = 0;
g.glGetShaderInfoLog(out, static_cast<GLsizei>(sizeof(log) - 1), &len, log);
detail = format("{} shader compile failed: {}",
stage == GL_VERTEX_SHADER ? "vertex" : "fragment",
len > 0 ? log : "(no info log)");
return false;
}
return true;
};
GLuint v = 0, f = 0;
const ScopeGuard delV([&]() { if (v) g.glDeleteShader(v); });
const ScopeGuard delF([&]() { if (f) g.glDeleteShader(f); });
if (!compile(GL_VERTEX_SHADER, vs, v) || !compile(GL_FRAGMENT_SHADER, fs, f)) {
return 0;
}
const GLuint prog = g.glCreateProgram();
if (prog == 0) {
detail = "glCreateProgram returned 0";
return 0;
}
g.glAttachShader(prog, v);
g.glAttachShader(prog, f);
g.glLinkProgram(prog);
GLint linked = GL_FALSE;
g.glGetProgramiv(prog, GL_LINK_STATUS, &linked);
if (linked != GL_TRUE) {
detail = "program link failed";
g.glDeleteProgram(prog);
return 0;
}
return prog;
}
// "noperspective interpolation" row - a real correctness render, not just a compile. A viewport-
// filling quad is drawn with strong perspective (left clip-w 1, right clip-w 8) and a varying that
// runs 0..1 across it. At the screen centre screen-linear interpolation gives 0.5 while perspective-
// correct gives 1/(w+1) ~= 0.11, so reading the centre texel tells the two apart. The varying is
// carried either through the native `noperspective` qualifier (extension present) or through the
// exact gl_Position.w / gl_FragCoord.w rewrite MobileGL applies when it is absent. Verdict:
// PASS - extension present and the native noperspective result is screen-linear;
// WARN - extension absent but the gl_Position.w/gl_FragCoord.w emulation renders screen-linear
// (correct, just the fallback path shipping shader packs hit on such devices);
// FAIL - either path renders perspective-correct / wrong (noperspective does not actually work),
// or the program will not compile/link, or the render errors.
// Requires the probe context to still be current.
void ProbeGlesNoperspective(ReportBuilder& builder, const MG_External::GLESCapabilities& caps,
const MG_External::GLESFunctionsTable& g) {
const Bool native = caps.SupportsNoperspectiveInterpolation;
const String pathNote = native ? "GL_NV_shader_noperspective_interpolation present (native path)"
: "GL_NV_shader_noperspective_interpolation absent (gl_Position.w / "
"gl_FragCoord.w emulation path)";
const auto fail = [&](const String& detail) {
builder.Fail("noperspective interpolation", pathNote + "; " + detail);
};
if (!g.glCreateShader || !g.glShaderSource || !g.glCompileShader || !g.glGetShaderiv ||
!g.glGetShaderInfoLog || !g.glDeleteShader || !g.glCreateProgram || !g.glAttachShader ||
!g.glLinkProgram || !g.glGetProgramiv || !g.glUseProgram || !g.glDeleteProgram ||
!g.glGenFramebuffers || !g.glBindFramebuffer || !g.glDeleteFramebuffers ||
!g.glGenRenderbuffers || !g.glBindRenderbuffer || !g.glRenderbufferStorage ||
!g.glFramebufferRenderbuffer || !g.glDeleteRenderbuffers || !g.glCheckFramebufferStatus ||
!g.glGenBuffers || !g.glBindBuffer || !g.glBufferData || !g.glDeleteBuffers ||
!g.glGetAttribLocation || !g.glVertexAttribPointer || !g.glEnableVertexAttribArray ||
!g.glViewport || !g.glClearColor || !g.glClear || !g.glDrawArrays || !g.glReadPixels ||
!g.glFinish || !g.glGetError) {
fail("the render entry points did not resolve through eglGetProcAddress");
return;
}
// Match MobileGL's own ESSL target (the device's version). At #version 300 es some drivers
// (Adreno) still treat `noperspective` as reserved even with the extension enabled; the ES 3.2
// form the backend actually emits compiles. Emulated shaders are version-agnostic but use the
// same header for consistency.
const Int esslVer = caps.GLESVersion.Major * 100 + caps.GLESVersion.Minor * 10;
const String header = format("#version {} es\n", esslVer >= 300 ? esslVer : 300);
static const char* const kVsNativeBody =
"#extension GL_NV_shader_noperspective_interpolation : require\n"
"in vec4 a_pos;\n"
"in float a_v;\n"
"noperspective out highp float v_out;\n"
"void main() { gl_Position = a_pos; v_out = a_v; }\n";
static const char* const kFsNativeBody =
"#extension GL_NV_shader_noperspective_interpolation : require\n"
"precision highp float;\n"
"noperspective in highp float v_out;\n"
"out vec4 fragColor;\n"
"void main() { fragColor = vec4(v_out, 0.0, 0.0, 1.0); }\n";
// Exactly MobileGL's emulation (verified against EmulateNoPerspectivePass output): pre-multiply
// the varying by clip-w in the vertex stage, recover with gl_FragCoord.w in the fragment stage,
// no noperspective qualifier (so the driver interpolates it perspective-correct).
static const char* const kVsEmuBody =
"in vec4 a_pos;\n"
"in float a_v;\n"
"out highp float v_out;\n"
"void main() { gl_Position = a_pos; v_out = a_v * gl_Position.w; }\n";
static const char* const kFsEmuBody =
"precision highp float;\n"
"in highp float v_out;\n"
"out vec4 fragColor;\n"
"void main() { fragColor = vec4(v_out * gl_FragCoord.w, 0.0, 0.0, 1.0); }\n";
while (g.glGetError() != GL_NO_ERROR) {
}
const String vsSrc = header + (native ? kVsNativeBody : kVsEmuBody);
const String fsSrc = header + (native ? kFsNativeBody : kFsEmuBody);
String linkDetail;
const GLuint prog = CompileLinkProgram(g, vsSrc.c_str(), fsSrc.c_str(), linkDetail);
if (prog == 0) {
fail(native ? "a noperspective program failed to build though the extension is advertised: " +
linkDetail
: "the emulation program failed to build: " + linkDetail);
return;
}
const ScopeGuard delProg([&]() { g.glDeleteProgram(prog); });
// 9x9 so the centre texel (4,4) sits exactly at NDC (0,0).
constexpr GLsizei kDim = 9;
GLuint rbo = 0, fbo = 0, vbo = 0;
g.glGenRenderbuffers(1, &rbo);
const ScopeGuard delRbo([&]() { if (rbo) g.glDeleteRenderbuffers(1, &rbo); });
g.glBindRenderbuffer(GL_RENDERBUFFER, rbo);
g.glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, kDim, kDim);
g.glGenFramebuffers(1, &fbo);
const ScopeGuard delFbo([&]() {
if (fbo) {
g.glBindFramebuffer(GL_FRAMEBUFFER, 0);
g.glDeleteFramebuffers(1, &fbo);
}
});
g.glBindFramebuffer(GL_FRAMEBUFFER, fbo);
g.glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, rbo);
if (g.glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
fail("the probe framebuffer is incomplete");
return;
}
// Interleaved [vec4 clip-pos, float v]. Left w=1, right w=8; x/y pre-multiplied by w so the quad
// still fills NDC after the perspective divide.
const GLfloat verts[] = {
-1.f, -1.f, 0.f, 1.f, 0.f, //
8.f, -8.f, 0.f, 8.f, 1.f, //
-1.f, 1.f, 0.f, 1.f, 0.f, //
8.f, 8.f, 0.f, 8.f, 1.f, //
};
g.glGenBuffers(1, &vbo);
const ScopeGuard delVbo([&]() { if (vbo) g.glDeleteBuffers(1, &vbo); });
g.glBindBuffer(GL_ARRAY_BUFFER, vbo);
g.glBufferData(GL_ARRAY_BUFFER, sizeof(verts), verts, GL_STATIC_DRAW);
g.glUseProgram(prog);
const GLint posLoc = g.glGetAttribLocation(prog, "a_pos");
const GLint vLoc = g.glGetAttribLocation(prog, "a_v");
if (posLoc < 0 || vLoc < 0) {
fail("the probe vertex attributes did not resolve");
return;
}
g.glEnableVertexAttribArray(static_cast<GLuint>(posLoc));
g.glVertexAttribPointer(static_cast<GLuint>(posLoc), 4, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat),
reinterpret_cast<const void*>(0));
g.glEnableVertexAttribArray(static_cast<GLuint>(vLoc));
g.glVertexAttribPointer(static_cast<GLuint>(vLoc), 1, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat),
reinterpret_cast<const void*>(4 * sizeof(GLfloat)));
g.glViewport(0, 0, kDim, kDim);
g.glClearColor(0.f, 0.f, 0.f, 1.f);
g.glClear(GL_COLOR_BUFFER_BIT);
g.glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
g.glFinish();
const GLenum drawError = g.glGetError();
if (drawError != GL_NO_ERROR) {
fail(format("GL error 0x{:x} while rendering the probe quad", drawError));
return;
}
GLubyte center[4] = {};
g.glReadPixels(kDim / 2, kDim / 2, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, center);
const GLenum readError = g.glGetError();
if (readError != GL_NO_ERROR) {
fail(format("GL error 0x{:x} while reading the probe pixel back", readError));
return;
}
// At the centre: screen-linear -> 0.5 (~128); perspective-correct -> 1/(8+1) ~= 0.111 (~28).
const float observed = static_cast<float>(center[0]) / 255.0f;
const int observedByte = center[0];
constexpr float kScreenLinear = 0.5f;
const bool screenLinear = observed > 0.5f * (kScreenLinear + 1.0f / 9.0f); // midpoint ~= 0.306
if (!screenLinear) {
fail(format("the centre texel read {} (~{:.3f}); expected the screen-linear ~0.5 - "
"interpolation came out perspective-correct, so noperspective does not work here",
observedByte, observed));
return;
}
if (native) {
builder.Pass("noperspective interpolation",
pathNote + format("; native noperspective renders screen-linear (centre {} ~= 0.5)",
observedByte));
} else {
builder.Warn("noperspective interpolation",
pathNote +
format("; the emulation renders screen-linear correctly (centre {} ~= 0.5), "
"but this is the fallback path with less driver coverage",
observedByte));
}
}
// Everything the "MobileGL reported ..." rows need from the GLES device probe.
struct GlesProbeSummary {
Bool capsValid = false;
@@ -527,6 +751,7 @@ namespace MobileGL::MG_Util::SelfTest {
builder.report.rendererInfo = format("{} ({})", caps.GLESRendererString, caps.GLESVersionString);
EvaluateGlesChecklist(builder, caps, glesFuncs);
ProbeGlesTimerQuery(builder, caps, glesFuncs);
ProbeGlesNoperspective(builder, caps, glesFuncs);
builder.report.formatCapabilities.emplace();
MG_Backend::DirectGLES::PopulateFormatCapabilities(
glesFuncs, caps, builder.report.formatCapabilities.value());