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glsl: simplify ES Vertex/Fragment shader requirements

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We really just needed to skip the existing ES < 3.1 check if we have
a compute shader, all other scenarios are already covered.

* No shaders is a link error.
* Geom or Tess without Vertex is a link error which means we always
  require a Vertex shader and hence a Fragment shader.
* Finally a Compute shader linked with any other stage is a link error.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Timothy Arceri
2016-01-27 16:16:01 +11:00
parent 55fa3c44bc
commit fd0b89ad8d
1 changed files with 28 additions and 28 deletions
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56
src/compiler/glsl/linker.cpp
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@@ -4566,38 +4566,38 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
if (!prog->LinkStatus)
goto done;
/* OpenGL ES requires that a vertex shader and a fragment shader both be
* present in a linked program. GL_ARB_ES2_compatibility doesn't say
/* OpenGL ES < 3.1 requires that a vertex shader and a fragment shader both
* be present in a linked program. GL_ARB_ES2_compatibility doesn't say
* anything about shader linking when one of the shaders (vertex or
* fragment shader) is absent. So, the extension shouldn't change the
* behavior specified in GLSL specification.
*
* From OpenGL ES 3.1 specification (7.3 Program Objects):
* "Linking can fail for a variety of reasons as specified in the
* OpenGL ES Shading Language Specification, as well as any of the
* following reasons:
*
* ...
*
* * program contains objects to form either a vertex shader or
* fragment shader, and program is not separable, and does not
* contain objects to form both a vertex shader and fragment
* shader."
*
* However, the only scenario in 3.1+ where we don't require them both is
* when we have a compute shader. For example:
*
* - No shaders is a link error.
* - Geom or Tess without a Vertex shader is a link error which means we
* always require a Vertex shader and hence a Fragment shader.
* - Finally a Compute shader linked with any other stage is a link error.
*/
if (!prog->SeparateShader && ctx->API == API_OPENGLES2) {
/* With ES < 3.1 one needs to have always vertex + fragment shader. */
if (ctx->Version < 31) {
if (prog->_LinkedShaders[MESA_SHADER_VERTEX] == NULL) {
linker_error(prog, "program lacks a vertex shader\n");
} else if (prog->_LinkedShaders[MESA_SHADER_FRAGMENT] == NULL) {
linker_error(prog, "program lacks a fragment shader\n");
}
} else {
/* From OpenGL ES 3.1 specification (7.3 Program Objects):
* "Linking can fail for a variety of reasons as specified in the
* OpenGL ES Shading Language Specification, as well as any of the
* following reasons:
*
* ...
*
* * program contains objects to form either a vertex shader or
* fragment shader, and program is not separable, and does not
* contain objects to form both a vertex shader and fragment
* shader."
*/
if (!!prog->_LinkedShaders[MESA_SHADER_VERTEX] ^
!!prog->_LinkedShaders[MESA_SHADER_FRAGMENT]) {
linker_error(prog, "Program needs to contain both vertex and "
"fragment shaders.\n");
}
if (!prog->SeparateShader && ctx->API == API_OPENGLES2 &&
num_shaders[MESA_SHADER_COMPUTE] == 0) {
if (prog->_LinkedShaders[MESA_SHADER_VERTEX] == NULL) {
linker_error(prog, "program lacks a vertex shader\n");
} else if (prog->_LinkedShaders[MESA_SHADER_FRAGMENT] == NULL) {
linker_error(prog, "program lacks a fragment shader\n");
}
}