lab orthographic projection (#7336)

Author: MjnMixael

code/graphics/matrix.cpp

@@ -27,6 +27,9 @@ static bool htl_2d_matrix_set     = false;
 
 static bool matrix_uniform_up_to_date = false;
 
+static bool  gr_ortho_override_active   = false;
+static float gr_ortho_override_distance = 0.0f;
+
 static matrix4 create_view_matrix(const vec3d* pos, const matrix* orient)
 {
 	vec3d scaled_pos;
@@ -127,7 +130,18 @@ void gr_set_proj_matrix(fov_t fov, float aspect, float z_near, float z_far) {
 
 	gr_last_projection_matrix = gr_projection_matrix;
 
-	if (std::holds_alternative<float>(fov)) {
+	if (gr_ortho_override_active && std::holds_alternative<float>(fov)) {
+		float half_h = gr_ortho_override_distance * tanf(std::get<float>(fov) * 0.5f);
+		float half_w = half_h * aspect;
+		if (gr_screen.rendering_to_texture != -1) {
+			create_orthographic_projection_matrix(&gr_projection_matrix, -half_w, half_w, half_h, -half_h, z_near, z_far);
+		} else {
+			create_orthographic_projection_matrix(&gr_projection_matrix, -half_w, half_w, -half_h, half_h, z_near, z_far);
+		}
+		// Clear after the first call so that shadow/deferred
+		// restore calls later in the same frame are not affected
+		gr_ortho_override_active = false;
+	} else if (std::holds_alternative<float>(fov)) {
 		float clip_width, clip_height;
 		clip_height = tan(std::get<float>(fov) * 0.5f) * z_near;
 		clip_width = clip_height * aspect;
@@ -393,3 +407,15 @@ void gr_matrix_set_uniforms()
 
 	matrix_uniform_up_to_date = true;
 }
+
+void gr_activate_ortho_proj_override(float camera_distance)
+{
+	gr_ortho_override_active   = true;
+	gr_ortho_override_distance = camera_distance;
+}
+
+void gr_deactivate_ortho_proj_override()
+{
+	gr_ortho_override_active   = false;
+	gr_ortho_override_distance = 0.0f;
+}

code/graphics/matrix.h

@@ -20,6 +20,11 @@ void gr_end_instance_matrix();
 void gr_set_proj_matrix(fov_t fov, float aspect, float z_near, float z_far);
 void gr_end_proj_matrix();
 
+// Orthographic projection override... when active gr_set_proj_matrix substitutes an
+// orthographic frustum sized to match the perspective view at the given camera distance.
+void gr_activate_ortho_proj_override(float camera_distance);
+void gr_deactivate_ortho_proj_override();
+
 void gr_set_view_matrix(const vec3d* pos, const matrix* orient);
 void gr_end_view_matrix();
 

code/lab/dialogs/lab_ui.cpp

@@ -569,6 +569,7 @@ void LabUi::show_render_options()
 			Checkbox("Hide Post Processing", &hide_post_processing);
 			Checkbox("Hide particles", &no_particles);
 			Checkbox("Render as wireframe", &use_wireframe_rendering);
+			Checkbox("Orthographic projection", &use_orthographic_projection);
 			Checkbox("Render without light", &no_lighting);
 			Checkbox("Render with emissive lighting", &show_emissive_lighting);
 			SliderFloat("Light brightness", &light_factor, 0.0f, 10.0f);
@@ -688,6 +689,7 @@ void LabUi::show_render_options()
 		getLabManager()->Renderer->setRenderFlag(LabRenderFlag::ShowEmissiveLighting, show_emissive_lighting);
 		getLabManager()->Renderer->setRenderFlag(LabRenderFlag::MoveSubsystems, animate_subsystems);
 		getLabManager()->Renderer->setRenderFlag(LabRenderFlag::NoParticles, no_particles);
+		getLabManager()->Renderer->setRenderFlag(LabRenderFlag::UseOrthographicProjection, use_orthographic_projection);
 		getLabManager()->Renderer->setEmissiveFactor(emissive_factor);
 		getLabManager()->Renderer->setAmbientFactor(ambient_factor);
 		getLabManager()->Renderer->setLightFactor(light_factor);

code/lab/dialogs/lab_ui.h

@@ -121,6 +121,7 @@ class LabUi {
 	bool show_weapons = false;
 	bool show_emissive_lighting = false;
 	bool show_particles = true;
+	bool use_orthographic_projection = false;
 
 	std::optional<vec3d> volumetrics_pos_backup = std::nullopt;
 };

code/lab/renderer/lab_cameras.h

@@ -54,6 +54,9 @@ class LabCamera {
 
 	/// Resets the camera orientation, pan, and zoom to default values
 	virtual void resetView() {}
+
+	/// Returns the distance from the camera to the point of interest, used to size the orthographic frustum.
+	virtual float getCameraDistance() const { return 0.0f; }
 };
 
 class OrbitCamera : public LabCamera {
@@ -84,6 +87,8 @@ class OrbitCamera : public LabCamera {
 
 	void updateCamera() override;
 
+	float getCameraDistance() const override { return distance; }
+
   private:
 	static constexpr float DEFAULT_DISTANCE = 100.0f;
 	static constexpr float DEFAULT_PHI = 1.24f;

code/lab/renderer/lab_renderer.cpp

@@ -3,6 +3,7 @@
 #include "globalincs/vmallocator.h"
 #include "graphics/2d.h"
 #include "graphics/light.h"
+#include "graphics/matrix.h"
 #include "lab/labv2_internal.h"
 #include "lab/renderer/lab_renderer.h"
 #include "lighting/lighting_profiles.h"
@@ -237,10 +238,18 @@ void LabRenderer::renderModel(float frametime) {
 	}
 	shockwave_move_all(frametime);
 
+	if (renderFlags[LabRenderFlag::UseOrthographicProjection]) {
+		float dist = labCamera->getCameraDistance();
+		if (dist > 0.0f)
+			gr_activate_ortho_proj_override(dist);
+	}
+
 	Trail_render_override = true;
 	game_render_frame(labCamera->FS_camera);
 	Trail_render_override = false;
 
+	gr_deactivate_ortho_proj_override();
+
 	Motion_debris_enabled = lab_debris_override_save;
 	Envmap_override = lab_envmap_override_save;
 	Cmdline_emissive = lab_emissive_light_save;

code/lab/renderer/lab_renderer.h

@@ -37,6 +37,7 @@ FLAG_LIST(LabRenderFlag) {
 	ShowAfterburners,
 	TimeStopped,
 	NoParticles,
+	UseOrthographicProjection,
 
 	NUM_VALUES
 };