wined3d: Declare gl_Position as invariant.

All D3D versions seem to basically guarantee invariance for the vertex position at the very least. In practice, desktop GL implementations also do the same. That's not necessarily the case for tile based renderers, where the cost of providing invariance might be non negligible. We want this behavior though, so let's ask for it explicitly. Based on a patch by Stefan Dösinger. Signed-off-by: Matteo Bruni <mbruni@codeweavers.com> Signed-off-by: Henri Verbeet <hverbeet@codeweavers.com> Signed-off-by: Alexandre Julliard <julliard@winehq.org>

wined3d: Declare gl_Position as invariant.
884b7c50 · Matteo Bruni · Alexandre Julliard · e86b4015 · 884b7c50
Commit 884b7c50 authored Nov 19, 2021 by Matteo Bruni Committed by Alexandre Julliard Nov 22, 2021
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glsl_shader.c dlls/wined3d/glsl_shader.c +12 -0

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--- a/dlls/wined3d/glsl_shader.c
+++ b/dlls/wined3d/glsl_shader.c
@@ -2184,6 +2184,14 @@ static void shader_generate_glsl_declarations(const struct wined3d_context_gl *c
        if (map & 1) shader_addline(buffer, "void subroutine%u();\n", i);
    }

+    if (version->type != WINED3D_SHADER_TYPE_PIXEL && version->type != WINED3D_SHADER_TYPE_COMPUTE)
+    {
+        if (version->type == WINED3D_SHADER_TYPE_HULL)
+            shader_addline(buffer, "out gl_PerVertex { invariant vec4 gl_Position; } gl_out[];\n");
+        else
+            shader_addline(buffer, "invariant gl_Position;\n");
+    }
+
    /* Declare the constants (aka uniforms) */
    if (shader->limits->constant_float > 0)
    {
@@ -7125,6 +7133,8 @@ static GLuint shader_glsl_generate_vs3_rasterizer_input_setup(struct shader_glsl

    shader_glsl_add_version_declaration(buffer, gl_info);

+    shader_addline(buffer, "invariant gl_Position;\n");
+
    if (per_vertex_point_size)
    {
        shader_addline(buffer, "uniform struct\n{\n");
@@ -8994,6 +9004,8 @@ static GLuint shader_glsl_generate_ffp_vertex_shader(struct shader_glsl_priv *pr
    if (shader_glsl_use_explicit_attrib_location(gl_info))
        shader_addline(buffer, "#extension GL_ARB_explicit_attrib_location : enable\n");

+    shader_addline(buffer, "invariant gl_Position;\n");
+
    for (i = 0; i < WINED3D_FFP_ATTRIBS_COUNT; ++i)
    {
        const char *type = i < ARRAY_SIZE(attrib_info) ? attrib_info[i].type : "vec4";