Validate varying count when compiling shaders

This avoids crashing on devices when a number of varyings greater than the device limit is used.

For now this accurately prints an error when compiling the shader, but the error text only pops up in the editor if the number of user varyings is above the limit.

Author: clayjohn

drivers/d3d12/rendering_device_driver_d3d12.cpp

@@ -6234,6 +6234,8 @@ uint64_t RenderingDeviceDriverD3D12::limit_get(Limit p_limit) {
 		case LIMIT_VRS_MAX_FRAGMENT_WIDTH:
 		case LIMIT_VRS_MAX_FRAGMENT_HEIGHT:
 			return vrs_capabilities.ss_max_fragment_size;
+		case LIMIT_MAX_SHADER_VARYINGS:
+			return MIN(D3D12_VS_OUTPUT_REGISTER_COUNT, D3D12_PS_INPUT_REGISTER_COUNT);
 		default: {
 #ifdef DEV_ENABLED
 			WARN_PRINT("Returning maximum value for unknown limit " + itos(p_limit) + ".");

drivers/gles3/storage/config.cpp

@@ -110,6 +110,11 @@ Config::Config() {
 	glGetIntegerv(GL_MAX_TEXTURE_SIZE, &max_texture_size);
 	glGetIntegerv(GL_MAX_VIEWPORT_DIMS, max_viewport_size);
 	glGetInteger64v(GL_MAX_UNIFORM_BLOCK_SIZE, &max_uniform_buffer_size);
+	GLint max_vertex_output;
+	glGetIntegerv(GL_MAX_VERTEX_OUTPUT_COMPONENTS, &max_vertex_output);
+	GLint max_fragment_input;
+	glGetIntegerv(GL_MAX_FRAGMENT_INPUT_COMPONENTS, &max_fragment_input);
+	max_shader_varyings = (uint32_t)MIN(max_vertex_output, max_fragment_input) / 4;
 
 	// sanity clamp buffer size to 16K..1MB
 	max_uniform_buffer_size = CLAMP(max_uniform_buffer_size, 16384, 1048576);

drivers/gles3/storage/config.h

@@ -62,6 +62,7 @@ class Config {
 	GLint max_texture_size = 0;
 	GLint max_viewport_size[2] = { 0, 0 };
 	GLint64 max_uniform_buffer_size = 0;
+	uint32_t max_shader_varyings = 0;
 
 	int64_t max_renderable_elements = 0;
 	int64_t max_renderable_lights = 0;

drivers/gles3/storage/utilities.cpp

@@ -465,4 +465,16 @@ Size2i Utilities::get_maximum_viewport_size() const {
 	return Size2i(config->max_viewport_size[0], config->max_viewport_size[1]);
 }
 
+uint32_t Utilities::get_maximum_shader_varyings() const {
+	Config *config = Config::get_singleton();
+	ERR_FAIL_NULL_V(config, 31);
+	return config->max_shader_varyings;
+}
+
+uint64_t Utilities::get_maximum_uniform_buffer_size() const {
+	Config *config = Config::get_singleton();
+	ERR_FAIL_NULL_V(config, 65536);
+	return uint64_t(config->max_uniform_buffer_size);
+}
+
 #endif // GLES3_ENABLED

drivers/gles3/storage/utilities.h

@@ -226,6 +226,8 @@ class Utilities : public RendererUtilities {
 	virtual String get_video_adapter_api_version() const override;
 
 	virtual Size2i get_maximum_viewport_size() const override;
+	virtual uint32_t get_maximum_shader_varyings() const override;
+	virtual uint64_t get_maximum_uniform_buffer_size() const override;
 };
 
 } // namespace GLES3

drivers/metal/metal_device_properties.h

@@ -124,6 +124,7 @@ struct MetalLimits {
 	uint32_t maxVertexInputBindings;
 	uint32_t maxVertexInputBindingStride;
 	uint32_t maxDrawIndexedIndexValue;
+	uint32_t maxShaderVaryings;
 
 	double temporalScalerInputContentMinScale;
 	double temporalScalerInputContentMaxScale;

drivers/metal/metal_device_properties.mm

@@ -303,6 +303,7 @@
 	limits.maxVertexInputAttributes = 31;
 	limits.maxVertexInputBindings = 31;
 	limits.maxVertexInputBindingStride = (2 * KIBI);
+	limits.maxShaderVaryings = 31; // Accurate on Apple4 and above. See: https://developer.apple.com/metal/Metal-Feature-Set-Tables.pdf
 
 #if TARGET_OS_IOS && !TARGET_OS_MACCATALYST
 	limits.minUniformBufferOffsetAlignment = 64;

drivers/metal/rendering_device_driver_metal.mm

@@ -3999,6 +3999,8 @@ bool isArrayTexture(MTLTextureType p_type) {
 			return (uint64_t)((1.0 / limits.temporalScalerInputContentMaxScale) * 1000'000);
 		case LIMIT_METALFX_TEMPORAL_SCALER_MAX_SCALE:
 			return (uint64_t)((1.0 / limits.temporalScalerInputContentMinScale) * 1000'000);
+		case LIMIT_MAX_SHADER_VARYINGS:
+			return limits.maxShaderVaryings;
 		UNKNOWN(LIMIT_VRS_TEXEL_WIDTH);
 		UNKNOWN(LIMIT_VRS_TEXEL_HEIGHT);
 		UNKNOWN(LIMIT_VRS_MAX_FRAGMENT_WIDTH);

drivers/vulkan/rendering_device_driver_vulkan.cpp

@@ -5886,6 +5886,10 @@ uint64_t RenderingDeviceDriverVulkan::limit_get(Limit p_limit) {
 			return vrs_capabilities.max_fragment_size.x;
 		case LIMIT_VRS_MAX_FRAGMENT_HEIGHT:
 			return vrs_capabilities.max_fragment_size.y;
+		case LIMIT_MAX_SHADER_VARYINGS:
+			// The Vulkan spec states that built in varyings like gl_FragCoord should count against this, but in
+			// practice, that doesn't seem to be the case. The validation layers don't even complain.
+			return MIN(limits.maxVertexOutputComponents / 4, limits.maxFragmentInputComponents / 4);
 		default:
 			ERR_FAIL_V(0);
 	}

servers/rendering/dummy/storage/utilities.h

@@ -94,6 +94,8 @@ class Utilities : public RendererUtilities {
 	virtual String get_video_adapter_api_version() const override { return String(); }
 
 	virtual Size2i get_maximum_viewport_size() const override { return Size2i(); }
+	virtual uint32_t get_maximum_shader_varyings() const override { return 31; } // Fair assumption for everything except old OpenGL-only phones.
+	virtual uint64_t get_maximum_uniform_buffer_size() const override { return 65536; } // Fair assumption for all devices.
 };
 
 } // namespace RendererDummy