mesa: don't pass Infs to the shader via gl_Fog.scale

This is for GLSL versions where Infs are undefined.

It also helps piglit/glsl-fs-fogscale that breaks when we move the fragment
shader code into the vertex shader across interpolation.

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Acked-by: Jesse Natalie on IRC
Acked-by: Erico Nunes on Gitlab
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25391>

diff --git a/src/gallium/drivers/d3d12/ci/d3d12-quick_gl.txt b/src/gallium/drivers/d3d12/ci/d3d12-quick_gl.txt
index 57e2231..fe9b49e 100644 (file)
--- a/src/gallium/drivers/d3d12/ci/d3d12-quick_gl.txt
+++ b/src/gallium/drivers/d3d12/ci/d3d12-quick_gl.txt
@@ -410,3 +410,7 @@ spec@nv_copy_depth_to_color@nv_copy_depth_to_color 1 0x223344ff,Fail
 spec@nv_copy_depth_to_color@nv_copy_depth_to_color 1 0x76356278,Fail
 spec@nv_copy_image@nv_copy_image-formats,Crash
 wgl@wgl-multi-context-single-window,Fail
+
+# remove this after https://gitlab.freedesktop.org/mesa/piglit/-/merge_requests/843
+# is merged and piglit is updated
+spec@arb_vertex_program@arb_vertex_program-property-bindings,Fail

diff --git a/src/gallium/drivers/lima/ci/lima-fails.txt b/src/gallium/drivers/lima/ci/lima-fails.txt
index 67384b7..50f91c1 100644 (file)
--- a/src/gallium/drivers/lima/ci/lima-fails.txt
+++ b/src/gallium/drivers/lima/ci/lima-fails.txt
@@ -672,3 +672,7 @@ spec@ext_framebuffer_multisample@renderbufferstorage-samples,Fail
 # New CTS failures in 1.3.6.3
 wayland-dEQP-EGL.functional.fence_sync.valid.egl_fence_persistent_buffer,Crash
 x11-dEQP-EGL.functional.fence_sync.valid.egl_fence_persistent_buffer,Crash
+
+# remove this after https://gitlab.freedesktop.org/mesa/piglit/-/merge_requests/843
+# is merged and piglit is updated
+spec@glsl-1.10@execution@glsl-1.10-built-in-uniform-state,Fail

diff --git a/src/mesa/program/prog_statevars.c b/src/mesa/program/prog_statevars.c
index 84e95f7..62d8a23 100644 (file)
--- a/src/mesa/program/prog_statevars.c
+++ b/src/mesa/program/prog_statevars.c
@@ -308,12 +308,22 @@ fetch_state(struct gl_context *ctx, const gl_state_index16 state[],
       else
          COPY_4V(value, ctx->Fog.ColorUnclamped);
       return;
-   case STATE_FOG_PARAMS:
+   case STATE_FOG_PARAMS: {
+      float scale = 1.0f / (ctx->Fog.End - ctx->Fog.Start);
+      /* Pass +-FLT_MAX/2 to the shader instead of +-Inf because Infs have
+       * undefined behavior without GLSL 4.10 or GL_ARB_shader_precision
+       * enabled. Infs also have undefined behavior with Shader Model 3.
+       *
+       * The division by 2 makes it less likely that ALU ops will generate
+       * Inf.
+       */
+      scale = CLAMP(scale, FLT_MIN / 2, FLT_MAX / 2);
       value[0] = ctx->Fog.Density;
       value[1] = ctx->Fog.Start;
       value[2] = ctx->Fog.End;
-      value[3] = 1.0f / (ctx->Fog.End - ctx->Fog.Start);
+      value[3] = scale;
       return;
+   }
    case STATE_CLIPPLANE:
       {
          const GLuint plane = (GLuint) state[1];